Substance use and substance use disorders in Africa: An epidemiological approach to the review of existing literature

Abstract

The relationship between man and substances that have abuse potentials, and whose use has been associated with the development or progression of substance use disorders has continued to evolve in terms of geography, economic implications, and time. History shows that local plants with psychoactive constituents can get exported worldwide through global travel, commerce, or even conquest. Time and globalization also change people’s relationship with substances of abuse; hence, an area that was initially alien to certain substances might evolve to becoming a trafficking hub, and then a destination. A case in point is Africa where a rapidly increasing prevalence of substance use/abuse and substance use disorder among adolescents and young adults is putting enormous strain on the economy, healthcare system, and society at large. However, there appears to be a paucity of scientific literature and data on the epidemiology, risk assessment, and contributing factors to substance use and the development of substance use disorders across Africa. In this narrative review, we examine extant literature (PubMed, Google scholar, Medline) for information on the prevalence, trends, and influencers of substance use and the development of substance use disorders. This is with a view of understanding the determinants of substance use and factors that influence the development of substance use disorders in the region, and how this information can be channeled towards developing a comprehensive intervention and treatment program.

Key Words: Addiction; Cannabis; Catha edulis; Datura metal; Drug dependence; Novel psychoactive substances

Core Tip: Substance use for medicinal and recreational purposes dates back centuries; however, in recent times, substance use is increasingly becoming a global public health crisis. In Africa, there is a consensus that substance use is emerging as a public health crise, but there appears to be a paucity of data on the epidemiology, risk assessment, and contributing factors to substance use and the development of substance use disorders across Africa. Here, we examined the extant literature for information on the prevalence, trends, and influencers of substance use and substance use disorders as it relates to Africa.

INTRODUCTION

Substance use and substance use disorders are increasingly becoming a global public health crisis, largely due to their increasing prevalence, worsening disability-adjusted life years, and high socioeconomic burden[1]. According to the World Drug Report, 2021[2], approximately 275 million people used drugs worldwide in the preceding year, with another 36 million persons diagnosed with substance use disorders globally[2]. In 2019 alone, substance use disorders were linked to about 18 million years of healthy life lost. Also, about 180000 deaths were directly linked to substance use disorders, while another half million deaths were attributed to illicit drug use[3].

Substance use is generally defined as a patterned use of any substance (including alcohol and/or psychoactive drugs) in quantities (or through methods) that are harmful to the user or others[4]. Substance use is often associated with varying degrees of intoxication, which is associated with alteration of judgment, attention, and perception. The use of alcohol, illicit drugs, and illegal use of prescription medications has been associated with negative impact on the individual’s health and productivity, as well as a high socioeconomic burden on the family and society[5,6]. Globally, there is a rapidly rising prevalence of substance use and substance use disorders, with an associated increase in the morbidity and mortality. Also, in Africa, the use of illicit substances such as cannabis (the most widely used substance in Africa, with a prevalence of between 5.2% and 13.5% in West and Central Africa), amphetamine-type stimulants, and benzodiazepines is increasing rapidly[7]. Again, in the last decade, Africa has begun to be recognized as a consumer and a destination for illicit drugs, compared to being previously regarded as mainly a transit zone for these drugs (serving as a link between Latin America and Europe)[8,9]. This reversal of the illicit drug trend is believed to be a contributing factor to the rapid development of substance use epidemic, particularly in the urban centers of Africa.

There is a consensus that substance use (particularly among adolescents and young adults) in Africa is emerging as a public health crises; however, there appears to be a paucity of scientific literature and data on the epidemiology, risk assessment, and contributing factors to substance use and the development of substance use disorders across Africa. Here, we reviewed the extant literature for information on the prevalence, trends, and influencers of substance use and the development of substance use disorders. This is with a view of understanding the determinants of substance use and the factors that influence the development of substance use disorders in the region, and how this information can be channeled towards developing a comprehensive interventions and treatment program.

History of substance use and substance use disorders

Substance use for medicinal, religious, and recreational purposes dates back centuries. The earliest mentions of the use of alcoholic or fermented beverages in Chinese writing dates far back as the 7^th millennia B.C.E[10], although there is also evidence from Sumerian writing (2100 B.C.E) of the use of opium from the poppy plant[11]. While the earliest use had been linked mainly to medicinal and religious purposes[10-12], there are also documentations of their use for recreational purposes[12]. However, since ancient times, humans have recognized the health problems that may be associated with excess alcohol consumption[12-14].

In 2019, the United Nations Office on Drugs and Crime reported an estimated 35 million people having a substance use disorder necessitating treatment[15]. Surveys and results of prospective studies examining patterns of drug use among the general population has revealed substance use peaks between 18 years and 25 years of age[15,16] with drug use among young people exceeding that of older people[15,17].

History of substance use in Africa: From transit nations to major illicit drug destinations

The African continent has a long history of drug cultivation, production, trade and consumption; and there are also indigenous plants and herbs with psychoactive effects such as cannabis resin (known as hashish in North Africa), Catha edulis (known as Kath in East Africa), and cannabis (known as dagga in Southern Africa) that have also been used traditionally for centuries[18-21]. In the last few years, rapidly growing large-scale trade and recreational use of opiates, synthetic psychoactive stimulants, and prescription drugs are emerging threats in the African continent[21].

The relationship between North Africa and cannabis has existed for centuries, predating the arrival of the Spanish and French in the 19^th century. Also, during the colonial era, cannabis was cultivated in small quantities across the northern Rif mountains in Morocco, and throughout the northern parts of Tunisia and Algeria[22]. While production was mainly to meet local demands (with some smuggling and exportation to Europe), the era following independence of the different countries in the region saw regulations and laws being enacted and enforced to control the production, sale, and use of cannabis. However, across the four countries (Morocco, Algeria, Tunisia and Libya) that make up the Maghreb (an area also known as northwest Africa), the drug trade has not only continued to grow, it is also evolving. In the last few decades, a region known mainly for the production of cannabis destined for other markets (particularly the European market) has increasingly become an important route for the trafficking of cocaine and different psychotropic pills. Since the beginning of the 21^st century, trafficking routes for cocaine, cannabis resin, and psychotropic pills that existed between South America, Africa, and Europe shifted to transect the Maghreb region[22]. This change has been partly attributed to an increase in the demand for drugs in the region, and the perturbations of other transit zones such as the Sahel region, which has become unstable. Most important is the geographic location of the region, being a link between Africa, Middle East and Europe. While drug transit routes through North Africa is increasing, of more importance is the increasing rate of consumption of these drugs in the region. The use of psychotropic drugs, which are very addictive, is nearing epidemic proportions in the region; also, other substances being consumed include cannabis, cocaine and opioids[22].

Before West Africa began to be considered a transit zone for drugs, it was also a producer of cannabis products (although not on the scale of the North African countries), which were shipped to Europe and the United States. Although, at the same time, marijuana was being imported into Nigeria from South Africa and a region now known as the Democratic Republic of Congo[23]. The smuggling of heroin through West Africa was first documented in 1952[23]; however, West Africa’s rise as a major drug smuggling hub began sometime in the 1960s, coinciding with a period of increased demand for illegal drugs, including marijuana which was grown and exported from Nigeria in large quantities to Europe. Despite attempts by governments in these countries to stem the tide of the marijuana export, marijuana trade continued illegally for several years until the demand for newer psychoactive substances such as cocaine and heroin overtook the demand for marijuana[24]. By the 990^th year of the 2^nd millennium and the 90^th year of the 20^th century, West Africa had become a major transit and repackaging center for substances such as cocaine and heroin through a transnational trade route that originated from South America and Asia, to Europe. While drug trafficking through Africa was not new, an intense clamp-down on the South-North American trade routes by the United States anti-narcotics strategies and the increase in demand for drugs across Europe saw to the rapid expansion of the West African trade routes in the early 21^st century[25,26]. The geography of the West African states (made up of large areas of uninhabited islands and archipelagoes found in countries like Guinea Bissau) eased transit and made detection difficult[27]. Also, the vulnerable political environment with the presence of civil wars/insur-gencies created fertile grounds for the development of criminal networks in the West African sub region[27].

Previously, when compared to West Africa, the drug trafficking routes through the Eastern belt of Africa were less robust; however, in the last few decades of this century, the trend is an increase in the trafficking of and the variety of trafficked drugs through the East African states of Kenya, Uganda, and Tanzania. Specifically, the trafficking of heroin and cocaine through these countries has grown considerably. Trafficking routes begin in Afghanistan where heroin is produced, through Pakistan and then East Africa enroute over Europe. The cocaine transnational trafficking routes began to go through East Africa in a bid to bypass the West African routes that were increasingly being watched by anti-drug trafficking authorities[28]. Also observed was that the increased consumption of these substances coincided with an increase in trafficking and affordability of the drugs.

In South Africa, a country in the southern region of Africa, the trafficking of drugs has increased. There are reports that since the period prior to and following the transition to democracy, there has been an escalation of drug trafficking. Trafficking in these parts has increased as a result of the easing of the strict control of land, air and sea borders, and an increase in international trade that occurred following the reintegration of South Africa into the committee of nations following the end of apartheid. Also, the effective policing of traditional smuggling routes prompting the search for other shipping routes also accounts for the increased trafficking of drugs through South Africa[29]. The increased trafficking is also worsening the substance use problems as a proportion of the drugs trafficked end up on the local market. There have also been reports that drugs such as methaqualone are also produced in clandestine laboratories in the region[30]. Overall, the level of affluence in the region makes it an attractive ‘emerging market’ for illicit drugs[30-32]. South Africa also has a history of drug use that dates as far back as the 15^th century. Cannabis, which is known as dagga in South Africa, has been consumed traditionally for centuries. The cannabis plant was brought to southern Africa by Saheli merchants from eastern Africa and some members of the bantu tribe of central and southern Africa where it has been cultivated since the 15^th century. Around the 16^th and 18^th century, the consumption of cannabis increased significantly[33]. Although initially popular only among the African population, over time, its use extended to the white population of South Africa[30].

Overall, while the current substance use epidemic in the African continent could be linked to the global trend in substance use, the transformation of African nations from mainly transit points in the international drug network to consumer countries would seem inevitable[34]. Also, the rapid socioeconomic changes that have occurred across the different countries that make up the African continent could have facilitated this shift in what can be assumed to be the “normal trend”.

EPIDEMIOLOGY OF SUBSTANCE USE ACROSS THE AFRICAN CONTINENT

Across Africa, reports spanning the last two decades show that substance use especially among adolescents and young adults is increasing at alarming rates[19,35-41]. The World Health Organization and the United Nations Office on Drugs and Crime reported, an exponential increase in the per capita consumption of alcohol as well as the cultivation, trade, and consumption of cannabis in most of the countries in Africa, with suggestions that this could inevitably have adverse socioeconomic and public health implications[42-44]. At the time, about 10 countries in Africa were listed among the 22 countries with the highest increases in the use of alcohol and other psychoactive substances including cannabis, tobacco, cocaine, and heroin[45]. In 2013, the United Nations Office on Drugs and Crime World Drug Report estimated that across the African continent, more than 28 million people had a current history of substance use. Cannabis was also reported to be the most commonly used drug on the continent, with the prevalence estimated to be 7.5%, which was almost twice the global average. The use of opioids was also reportedly on the rise[46].

While it has been recognized that Africa is beginning to battle a drug use epidemic, with an estimated 37000 people in Africa dying annually from substance use-associated complications[47-49]; available data for Africa are still either weak or nonexistent. To date, in many African countries, there is still a paucity of national data regarding the epidemiology and patterns of substance use across populations, with available data largely limited to small prospective population studies and retrospective hospital-based studies.

In West Africa, the paucity of data regarding the prevalence of drug use undermines our ability to adequately understand the full extent of the substance use problem, and how it is creating a public health problem that further threatens the already fragile health system that currently exists. It also creates a false sense of safety, because it fosters the erroneous belief that substance use is under control. However, in the last few years, this trend is becoming more difficult to ignore, because there is now increasing evidence from the increase in crime/criminal behaviors and an increasing need for medical attention that arises from the development of substance use disorders or complications of risky behaviors that are consequences of drug use. In the last decade, in West African countries like Ghana, incident reports from health professionals, lawyers, and law enforcement officers are beginning to show dramatic increases in the domestic consumption of illicit drugs. However, these reports do not adequately portray the scale of substance use problem; because there is a dearth of national figures that can accurately quantify the prevalence of drug use in Ghana or most other West African countries. All of these result in a huge dependence on small-scale cross-sectional studies (Table 1). A 2008 population-based study conducted among school-going adolescents, reported that the prevalence of any substance use in the preceding 1 mo was 3.6%[50]. The results of an earlier study that interviewed a sample of 894 high school students with a mean age of 17.4 years, reported that the lifetime alcohol use in these cohort was 25.1%; with cigarette use and lifetime marijuana use being 7.5% and 2.6%, respectively. Also, current alcohol use was reported to be 46.2%; current cigarette and marijuana use was 44.6% and 58.3%, respectively[51]. The result of a 2014 cross-sectional survey of a sample of 227 street children and youths revealed that the current prevalence of alcohol and marijuana use was 12% and 16.2%, respectively. Sex differences in substance use was also reported with more females using alcohol, marijuana, and smoking cigarettes compared to males[52]. In Nigeria, reports from small-scale studies have demonstrated a high prevalence of substance use among adolescents and young adults. A 2009 study that examined the prevalence of substance use among 280 students at a senior secondary school in a town in Northwest Nigeria, revealed that about 56% of them had a history of substance use, with the most common being kolanut, cigarettes, and marijuana[53]. Idowu et al[54] also examined the prevalence of substance use among 249 students (mean age = 16.3 ± 2 standard deviations) of secondary schools in a metropolis in south western Nigeria and reported that the prevalence of alcohol and substance use was 21.7% and 26.3%, respectively, with tramadol being the substance of choice[54]. The magnitude of the effect was best conveyed by the results of the 2018 National Drug Use Survey which revealed that approximately 14.3 million people (accounting for 14.4% of the population aged between 15 years and 64 years) had a history of current and continuing substance drug use, with close to 3 million having at least a form of drug use disorder[48,55]. A difference was also observed in the prevalence of drug use between the Northern and Southern geopolitical zones, with a higher prevalence in the regions in the south (13.8%-22.4% of the population) compared to those in the northern geopolitical zone (10%-14.9% of the population). In Nigeria, cannabis was the most commonly used drug, which was followed by opioids (non-prescription or in cough syrup)[48,56]. The survey also highlighted a rise in the current use of psychoactive substances (including cannabis), the non-medical use of prescription drugs such tramadol, codeine, morphine or cough syrups that contain codeine or dextromethorphan[55]. Also observed was an overall high incidence of drug use (excluding alcohol) among males compared to females (10.8 million males vs 3.4 million females), although the sex difference in the non-medical use of prescription opioids, cough syrups, and sedatives was not as significant (6% among men compared to 3.3 among women). The survey also reported a higher incidence of drug use among young adults (24-39) compared to those aged 24 and below[55].

Table 1 Epidemiology of substance use across the African continent.

Region	Study type	Study group	Result	Ref.
Ghana	Population-based study	School-going adolescents	3.6% prevalence of substance use in the preceding 1 mo	[50]
Ghana	Cross-sectional study	894 high school students with a mean age of 17.4 yr	Lifetime alcohol use was 25.1%; with cigarette use and lifetime marijuana use being 7.5% and 2.6% respectively. Current alcohol use was 46.2%; current cigarette and marijuana use was 44.6%; and 58.3%, respectively	[51]
Ghana	Cross-sectional survey	227 street children and youths	Current prevalence of alcohol and marijuana use was 12% and 16.2%, respectively	[52]
Nigeria	Cross-sectional study Northwestern Nigeria	280 secondary school students	56% of them had a history of substance use (kolanut, cigarettes, and marijuana)	[53]
Nigeria	Cross-sectional study Southwestern Nigeria	249 secondary school students	Prevalence of alcohol and substance use was 21.7% and 26.3%, respectively, tramadol being the substance of choice	[54]
Nigeria	National drug survey	Population-based	Approximately 14.3 million people (accounting for 14.4% of the population aged between 15-64 yr) had a history of current and continuing substance drug use, with close to 3 million having at least a form of drug use disorder	[55]
Ethiopia	Demographic and health survey	Population-based	4% of youths and 6.3% of individuals in age groups of 25-29 yr smoked cigarettes, while 53% of men and 45% of women consumed alcohol	[59]
Ethiopia	Analysis of data extracted from the 2016 Ethiopia Demographic and Health Survey	12688 male cohorts	62.5% (7931 males) had a current history of substance use (alcohol, Kath, or tobacco). Inhabitants of the Amhara, Tigray and Oromia regions had a current substance use prevalence of 18.5%, 14.2% and 12.8%, respectively	[60]
Ethiopia	Cross-sectional study Northeastern Ethiopia	730 university students in	Lifetime prevalence of alcohol consumption, Kath chewing, and cigarette smoking was 33.1%, 13% and 7.9%, respectively, and current prevalence was 27.9%, 10.4% and 6.4%	[61]
Ethiopia	Cross-sectional study	794 university students	73.7% had a history of substance use with the lifetime prevalence of illicit drugs being 23.3%	[63]
Egypt	Hospital-based study (single-center experience)	First episode drug-induced psychosis patients	Substance abuse rates are as high as 10%-20% the global average with cannabis and tramadol being the most abused substance	[65]
Tunisia	Cross-sectional study	298 persons with a history of drug use	Cannabis was the most widely consumed illicit drug, followed by benzodiazepines, buprenorphine, cocaine, and ecstasy	[68]
Tunisia	Mediterranean school survey project	Secondary school students	Tobacco, alcohol, and cannabis were the substances most frequently used	[66,67]
Tunisia	Epidemiologic/toxicological investigation Northern Tunisia	11170 suspected drug users	A preponderance of males (97.4%), with a median age of 29 ± 7.91 yr. 91.3 % were single	[69]
South Africa	School-based survey	Secondary school students	13% of the students (aged 19 yr and below) had an history of cannabis use, although current use was 9%. 12% had a current use of heroin, 11% used inhalants and 6% consumed mandrax	[73]
South Africa	National household survey	Population-based	Past 3 mo prevalence for cannabis among 15-19-years-old was 3%	[74]

In East Africa, there is also a dearth of national statistical data on the prevalence of substance use in a number of the countries, with researchers and policy makers needing to rely on information from studies involving subsets of the populations. In Ethiopia, alcohol, Kath and tobacco are the most popular substances that are consumed[57,58]. A 2012 Ethiopian demographic and health survey reported that 4% of youths and 6.3% of individuals in age groups of 25-29 years smoked cigarettes, whereas 53% of men and 45% of women consumed alcohol[59]. Also, the results of a study by Girma et al[60] that analyzed data extracted from the 2016 Ethiopia Demographic and Health Survey revealed that of the 12688 male cohorts of the Ethiopian Demographic and Health Survey, at least 62.5% (7931 males) had a current history of substance use (alcohol, Kath, or tobacco) as at the time of the survey. Inhabitants of the Amhara, Tigray, and Oromia regions have a current substance use prevalence of 18.5%, 14.2%, and 12.8%, respectively. Alcohol (53.1%) is reportedly the most commonly consumed substance, followed closely by Kath, which has a prevalence of 25.9%[60]. Reports of small cross-sectional studies have also corroborated the high prevalence of alcohol, Kath, and cigarette smoking among Ethiopian youths[61]. Adere et al[61] examined a cohort of 730 university students in Northeastern Ethiopia and reported that the lifetime prevalence of alcohol consumption, Kath chewing, and cigarette smoking was 33.1%, 13%, and 7.9%, respectively, whereas the current prevalence of these substances is 27.9%, 10.4%, and 6.4%, respectively[61]. The prevalence observed in this study was similar to that observed in an earlier study carried out among the students at a University in a town in North Ethiopia[62]. While earlier studies among university students did not report evidence to suggest the use of illicit drugs, the results of a 2021 cross-sectional study among 794 students of Addis Ababa University, showed that 73.7% of the study participants had a history of substance use with the use of illicit drugs having a lifetime prevalence of 23.3%[63]. However, similar to other studies, alcohol, Kath, and cigarettes were still the most commonly abused substances[63].

In North Africa, data and information on substance use, production, trafficking, and consumption are also limited. This has been attributed to a lack of capacity for data collection and analysis[64]. In Egypt, there are reports that substance abuse rates are as high as 10%-20% the global average, with cannabis and tramadol being the most abused substances[65]. In Tunisia, an increase in the trafficking and consumption of psychoactive substances have been observed since the political uprising that occurred in 2011[66]. There have also been reports of increased availability of drugs of abuse, particularly to school students[66]. These increases have been confirmed by a few epidemiological studies[66-68]. Moslah et al[68] carried out a study to examine the pattern of substance use among 298 persons with a history of drug use between 2010 and 2015. The results showed that among these cohort of young adults, cannabis was the most widely consumed illicit drug, followed by benzodiazepines, buprenorphine, cocaine, and ecstasy[68]. Reports from the Mediterranean School Survey Project on Alcohol and Other Drugs (II) carried out in Tunisia in 2017 revealed that tobacco, alcohol, and cannabis were the substances most frequently used by secondary school students[67], whereas psychotropic drugs such as ecstasy, cocaine, and buprenorphine were less frequently consumed. More importantly, it was observed that the frequency of use of these substances has increased significantly since the first survey published in 2014[66]. Chaouali et al[69] carried out an epidemiologic/toxicological investigation to evaluate patterns of drug abuse in 11170 suspected drug users. Urine samples collected between January 2016 and December 2018 were also analyzed. Results revealed a preponderance of males (97.4%) compared to females, with a median age of 29 ± 7.91 years. Also observed was that a large percentage of these drug users were single (91.3%). Examination of the urine samples revealed that about 48.4% tested positive for illicit drugs, with cannabis being the most widely consumed drug (95%), others were benzodiazepines, buprenorphine, cocaine, and opiates (0.13%). There was also a history of poly drug use[69].

In Southern Africa (although there are limited national data in most countries in the region), a rise in substance use has been reported[70]. In some of these countries including Zimbabwe, there is anecdotal evidence suggesting an increase in substance use among adolescents and young adults, with prevalence of substance use reportedly ranging from 6.1% to 13.8%[70]. Alcohol, cannabis, heroin, glue, and cough mixtures are among the most commonly consumed products in Zimbabwe. Cannabis, which is commonly known as mbanje, is grown locally (also smuggled into Zimbabwe from Malawi and Mozambique), and remains the most popular illicit drug among young Zimbabweans. Drugs are also trafficked through Zimbabwe to other countries in the region, including South Africa. In South Africa, an increase in substance use has been reported, which has been linked to the increased availability of illicit drugs including cannabis, cocaine, heroin, amphetamines, and ecstasy; either from diversion during trafficking or increased cultivation and local production[29,30,71,72]. Other factors that have contributed to the increase in substance use include an increase in migration and easing of border controls following the commencement of democracy, which have facilitated the development of youths’ movements that indirectly or directly promote substance use[30]. Results from surveys have revealed a gradual increase in cannabis consumption among adolescents and young adults in South Africa.

A 2002 school-based survey reported that 13% of the students (aged 19 years and below) had an history of cannabis use, although current use was 9%. About 12% had a current use of heroin, 11% used inhalants, and 6% consumed Mandrax[73]. The results of another study (a 2005 National household survey) showed that the prevalence in the past 3 mo for cannabis among 15-19-years-old was 3%[74]. In another study examining the prevalence and patterns of use of illicit substances among persons presenting at drug treatment centers in South Africa, it was revealed that cannabis (16.9%), methamphetamine (12.8%), cocaine (9.6%), and prescription drugs (2.6%) were the substances commonly used among patients. Also, there was evidence of poly drug use, with cannabis and mandrax having a prevalence of 3.4%, whereas heroin and opiates had a prevalence of 9.2%[75].

Prior to 1994 and the first democratic elections, alcohol, cannabis, and methaqualone were the primary substances of misuse in South Africa. With South Africa’s transition to democracy and subsequent reopening of borders, there has been an influx of and a growing burden of harm associated with illicit drug use. Alcohol, however, remains the most commonly misused substance, with 14% of the population having a lifetime diagnosis of alcohol abuse and/or dependence (Herman et al[76], 2009). Although the overall levels of alcohol consumption do not exceed those in the developed world, the pattern of consumption differs markedly, with hazardous and binge drinking being common.

New and emerging psychoactive substances in Africa

Use of novel psychoactive substances is an emerging trend in substance use that is fast becoming a public health challenge globally[77,78]. Novel or new psychoactive substances have been defined by the United Nations Office on Drugs and Crime[79] as substances of abuse (existing either in its pure form or as a preparation) that are not controlled by either the 1961 or 1971 conventions on narcotic drugs and psychotropic substances, respectively, but pose significant threats to public health globally due to spikes in intoxications and fatalities associated with their use[79,80]. The term ‘novel’ or ‘new’ that is used in relation to these substances depicts their recent emergence in the global market. Substances that currently fall within the novel psychoactive substance category include (but are not limited to) synthetic cathinone and cannabinoids, synthetic opioids, image and performance-enhancing substances, tryptamine derivatives, piperazines, phencyclidine-like dissociatives, gamma amino-butyric acid (A)/beta receptor agonists, novel hallucinogens, benzodiazepines and psychotropic plants/herbs[77,81,82].

In the last few years or more, there has been a growing demand and supply chain for these new psychoactive substances[77,78,81]. In the last 10-12 years, the number of novel psychoactive substances has increased considerably. In 2009, only about 166 of them had been detected; however, by 2019, the number had risen to about 950, with more than 70% of these substances available in Europe[80,83]. While in the developed economies, a lot is being done to ensure continued documentation of novel psychoactive substances as they emerge, it would seem that Africa is only beginning to awaken to the emerging public health threat that these substances pose to her teeming population of adolescents and young adults[82]. While the lifetime prevalence of novel psychoactive substance use in countries such as the United States have been examined[80], there is a paucity of data on the prevalence of novel psychoactive substance use in Africa. Although across the continent, there is increasing awareness of the dangers of novel psychoactive substance use.

In 2017, attention was called to an increase in the use of designer drugs in Nigeria. Some of these substances which have street names such as “black mamba”, Colorado”, “Lamba”, “happy boy”, and” Scooby snax” are believed to contain synthetic cannabinoids. Their use is associated with a rise in the incidence of hallucinations, convulsions, psychiatric disorders, kidney failure and fatalities[84]. News outlets, including the British Broadcasting Corporation News and Premium Times, also reported that the use of and addiction to non-conventional psychoactive substances such as tramadol and codeine cough syrups among Nigerian youths was reaching epidemic proportions[85,86]. In Nigeria, available novel psychoactive substances also include mixtures with street names such as “gutter water”, a cocktail of cannabis, tramadol, codeine and ethanol), and “monkey tail”, a cocktail of locally made gin and cannabis (seeds, leaves, stems, and roots). Some people have also been in a state of euphoria from drinking the mixture of specific carbonated drinks and menthol flavored candies[82]. The sniffing of dry human fecal matter, dry cassava leaves and seeds, Datura metal seeds, Moringa leaf, burnt tires, sewer gas, and nail polish have also been reported[82,87]. Different parts of some lizards, including the whitish part of their dung, are also smoked in a bid to achieve a “high”[82,87]. The inhalation of urine, sewage, petrol, and glue are also common practice among drug users in Africa. It is believed that the hallucinogens present in hydrocarbons from petrol, and gases produced from fermentation of sewage have the ability to cause a “euphoric high” similar to (but longer lasting) when compared to that derived from the ingestion of cocaine[88].

In southern Africa, particularly South Africa, there have been reports of the use of “Nyaope” also known as “Whoonga”, which is a cocktail of low-grade heroin (black tar heroin), marijuana, antiretroviral drugs (Efavirenz), and other undisclosed substances[88]. In East African countries such as Uganda and Kenya, the habit of using novel psychoactive substances such as the sniffing of aviation gas/jet fuel, toluene and glue is reaching epidemic proportions among persons aged between 16-25 years[89-91]. Other substances that are abused in this region include “kuber” and“ shisha”, also known as hookahs ,which are variants of smokeless tobacco. There have been reports that compared to cigarettes, the smoking of the shisha or hookah pipe exposes the user to higher volumes of smoke containing high levels of benzene, tar, and other carcinogens and increased risk of lung cancer[92-95].

In Northern Africa, the smoking of hashish and the chewing of Kath has become very rampant. Although there is little data from the region regarding the prevalence and patterns of use of novel psychoactive substances; reports from studies carried out in Egypt have suggested that the estimated prevalence of novel psychoactive substance use among adolescents in the country are largely underestimated[96]. However, tabloid reports have called attention to an increasing demand and use of novel psychoactive substances including “voodoo” and “strox” among adolescents and young adult in Egypt[97,98]. “Voodoo” is gaining popularity rapidly, and it is usually packaged and sold as an herbal incense. “Voodoo” is a heterogeneous mixture of several psychoactive substances, including synthetic cannabinoids, tramadol, amphetamine, methadone, benzodiazepines, penitrem A (a neurotoxin) and morphine derivatives. The concentrations of the chemical constituents and adulterants of voodoo also vary substantially among the different clandestine laboratories that produce it[96,99]. Another novel psychoactive substance that is gaining popularity in Egypt is “Strox”[100]. “Strox” or “Egyptian Spice” has been reported to account for approximately 4.3% of the over 10400 patients requiring medical support for drug-related complications[101]. Also, addiction to “strox” was responsible for 22% of calls to the addiction center hotline[101]. “Strox” is a potent synthetic narcotic that is mixed with tobacco and smoked; it is compounded in clandestine laboratories by adding veterinary grade chemicals to aromatic herbs such as marjoram. There have also been reports of the addition of pesticides to increase the potency, although this increases the toxicity[97].

The search for novel psychoactive substances is fueled by the need to create drugs that are able to evade the chemical processes used for detection and the legal processes that criminalizes the use and possession of conventional drugs of abuse. Also, the need for compounds that deliver fast and sustained psychoactive effects when compared to the conventional drugs also drive the search for novel psychoactive compounds[102]. However, the variability of the chemical constituents and/or adulterants of the different compounds present a conundrum for the health professional who has to decipher and manage the divergent symptoms and signs that complicate the use of these substances. Hence. there is an increasing need for continuous surveillance so that new or emerging psychoactive substances can be discovered before they wreak havoc on our communities.

African plants and herbs with psychostimulant potential: Are they being abused?

Several plants and parts of plants have been shown to have central nervous system effects[103-109]. Also, current literature reveals that novel psychoactive substances can be derived from either synthetic compounds or from bioactive principles of natural compounds. These bioactive principles which are mainly alkaloids are present in a wide variety of plants including Ayahuasca, Catha edulis and nicotiana tabacum; and have been reported to possess hallucinogenic and/or stimulant effects[110]. Plants with psychoactive properties are found all over the globe and have been used for centuries by humans, for religious, therapeutic and recreational purpose[111,112]. Studies have shown that the bioactive principles of these plants enable the profound alteration of the human perception allowing for divination, ancestral contact, and spiritual enlightenment[111-113].

Africa has a high floral diversity and a rich tradition of indigenous medicinal plant and herb use[111]. Africa is also rich in flora of medicinal plants that possess central nervous system effects[107]. Although there is a paucity of ethnobotanical surveys on African plants with psychoactive effects, evidence from African traditional healers and diviners who use plants such as the ‘Ubulawu’, a preparation containing Sileneundulata and Synaptolepis are pointers that there are plants indigenous to Africa that contain compound which have mood altering effects[113]. A few plant species that are indigenous to Africa, such as the Cola species (Cola nitida, and Cola acuminata), Catha edulis (Kath), Datura species (Datura stramonium), Pausinystalia yohimbe (Burantashi Pausinytalia yohimbe) and Tabernanthe iboga have reported psychoactive properties[111,114], and have been used recreationally (Table 2) for centuries in the countries in which they are cultivated. However, in recent times, the use of and dependence on some of these plants by adolescents and young adults (either alone or combined with established illicit drugs) is reaching epidemic proportions. In this section, we reviewed the abuse potential of some psychoactive plants that are indigenous to the African continent.

Table 2 African plants and herbs with psychostimulant potential.

Region	Herbal preparation	Plant	Bioactive compound	Central nervous system activity	Toxicity	Ref.
East Africa	Khat chewing, drink made from dried leaves or smoking dried leaves	Catha Edulis	Phenylalkylamines and the cathedulins (Cathinone)	Improves performance, stay alert and to increase work capacity, excitement, appetite loss and euphoria	Memory impairment, sleeping disorders, liver toxicity, cardiovascular disease, psychosis and poor academic performance	[115,117,124-126]
West Africa	Different parts of the plant are smoked or used to make concoctions	Datura specie including stramonium and Datura metal	Atropine, scopolamine, and hyoscamine	Anticholinergic and hallucinogenic activity	Hyperthermia, tachycardia, delirium, pronounced amnesia, severe mydriasis, bizarre behaviors and painful photophobia	[135,136,141,145-148]
West Africa	Root bark concoctions	Tabernanthe iboga	Ibogaine	Stimulatory, hallucinogenic, and sedative effects	Development of ataxia, tremor, cardiac toxicity, and death	[149-151]
South Africa	Ubulawu drink	Silene undulata and Synaptolepis	Triterpenoid saponins	Mood altering effects including stimulating vivid or lucid dreams	Confusion	[113]
South Africa	Chewed, smoked, snorted or swallowed	Sceletium tortuosum	Mesembrenone, mesembrenol, mesembrine and tortuosamine	Increased libido, decreased stress, euphoria and appetite suppression	Anxiety, headache, hypertension, irritability, insomnia and nausea	[154,155]

Kath (Catha edulis Forsk) is a flowering plant native to countries in East Africa and the Horn of Africa. Fresh young leaves and twigs from Kath are chewed daily by large populations of people for its psycho-stimulatory properties. The chewing of Kath dates back centuries, being a practice that is rooted in tradition, social custom and the culture of the indigenous populations[115]. It has been reported that more than 20 million people worldwide chew Khat[116,117]. Although traditionally a custom associated with older middle Eastern and Eastern African men, Khat’s use is now expanding to include women and younger persons. In the Eastern region of Ethiopia, approximately 30% of adolescent girls and 70% of adolescent boys chew Khat. The active principle contained in Khat is cathinone (an alkaloid), which is a stimulant that causes excitement, appetite loss and euphoria[117]. In countries such as Somalia, Ethiopia, Djibouti, and Kenya, the dependence on Kath is warranting its consideration as a substance of abuse. In Somalia a law prohibiting the use, cultivation, importation and trade of Kath was enacted and enforced by comprehensive national program[118]. At about the same period (approximately two decades ago), Kath was also considered by the World Health Organization and classified as a drug of abuse, although its abuse potential was not thought to constitute a serious problem compared with that of alcohol or tobacco[119]. Across a region extending across Africa and the Middle East, predominantly among the Ethiopians, Somalians and Yemenis, approximately 5 to 20 million people use Kath[116,120], with the consumers engaged in the practice for the best part of a day resulting in a loss of manpower and national income[121,122]. In 2005, a survey by the World Health Organization revealed a prevalence of 20% Kath abuse in Kenya, exceeding the prevalence observed in most of the other countries in the region[123]. However, more recent studies are demonstrating that in spite of attempts by the respective countries to criminalize the use of Kath, Kath chewing is fast becoming a common practice among young adults in countries like Kenya, Ethiopia, Somalia, Djibouti[124-126]. In Ethiopia, a study carried out among academic staff of a university revealed that the lifetime prevalence of Kath chewing was 41%[126], while another study carried out among college students reported a prevalence of 42%[124]. In Kenya, a recent household survey revealed that the prevalence of current Kath chewing in the region was 36.8%[125], which would suggest a significant rise from the 20% prevalence reported by the World Health Organization[123]. While Kath chewing was not previously known outside the regions within which it was cultivated, the effects of migration and trade have propelled it to a widely used psychostimulant globally[115,127]. Kath chewing has been associated with adverse health effects that is creating public health challenges in countries across Asia, Europe, Australia, and the United States of America[128-130]. When chewed concurrently with tobacco, there have been reports of cardiovascular stress response[129]. It has also been associated with the alteration of physical, mental, social and cognitive aspects of human functioning[131]. Chewing Kath chronically has been reported to cause memory impairment, sleeping disorders, liver toxicity, cardiovascular disease, psychosis and poor academic performance[126,132]. While attempts are being made by countries to criminalize the importation and trade of Kath, smugglers continue to find new avenues and trade routes. For example, in 2016, the National Drug Law Enforcement Agency of Nigeria reported seizures of Kath load, which was possibly destined for the Nigerian market or enroute countries[133]. However, in 2020, the United States customs reported seizure of Kath load from Nigeria destined for the United States suggesting that Nigeria is fast becoming a Kath transit hub[134].

In Nigeria, complicating the substance abuse epidemic is the emerging trend of experimenting with plant extracts or brews from a group of flowering plants belonging to the Datura specie, of the nightshade family Solanaceae[135,136]. Although members of the Datura specie which are broadly known as thorn apple, devil’s apple, devil’s trumpet or angel’s trumpet have their origin in central Americas and in the south-west region of the United States if America[137,138], they have become naturalized all over the world, being widespread in Asia, Europe, and Africa[139]. The datura specie is made up of herbs and shrubs with erect or branched stems, with alternate simple basal leaves and opposite leaves on terminal branches[139]. The fruit has a spiny capsule and reniform seeds[139,140]. All parts of the Datura stramonium and Datura metal plant has been shown to contain tropane alkaloids such as atropine, scopolamine, and hyoscyamine which have significant anticholinergic and hallucinogenic activity[141]. The high tropane alkaloid content of these plants increases their medicinal value and also opens them up to potential abuse. In Nigeria, Datura stramonium (thorn apple, devil’s snare, devil’s trumpet or jimsonweed) and Datura metal (Indian thorn apple) are naturalized. Similar to a number of countries across the world (United States of America and Canada) where there has been reports of datura-induced poisoning among adolescents who abuse the plant for its hallucinogenic effects[142-144], adolescents and young adults in Nigeria are also experimenting with the plant and getting poisoned[136]. Datura metal grows wildly (although at times it is cultivated) across the different regions of Nigeria where it is called ‘Myaramuo’ by the Igbos of south eastern Nigeria, ‘Zakami’ by Hausas of northern Nigeria and ‘Apikan’ by the Yorubas of southwestern Nigeria[145,146]. Datura stramonium also grows as a weed and is also cultivated across the different states of Nigeria. It is known as ‘Gegemu’ by the Yorubas and ‘Zakami’ by the Hausas[136]. Both plants have been reported to have hallucinogenic and euphoric effects when the different parts of the plant are either smoked or used to make concoctions[147]. Datura stramonium poisoning is associated with hyperthermia, tachycardia, delirium, pronounced amnesia, severe mydriasis, bizarre behaviors and painful photophobia[136,148]. These features can appear as early as 30 min to 1 h following consumption of the extract or smoking of the weed and have been reported to last several hours to days or at times even as long as 2 wk[148].

Another plant with psychoactive properties is the Western African shrub Tabernanthe iboga from whose root bark ibogaine, a hallucinogenic alkaloid is extracted. Traditionally, the concoctions from the roots have been used for their stimulatory, hallucinogenic, and sedative effects[149]. Ibogaine has been reported to exhibit stimulant effects at low doses and result in the development of hallucinations at high doses. Its use has also been associated with the development of ataxia, tremor, cardiac toxicity, and death[149-151]. There have also been reports that ibogaine has anti-addictive properties, although its use is limited by its deleterious effects[152,153].

In southern Africa, the use of extracts, dried-powdered herb, tincture, tea bags and seeds of the plant sceletium tortuosum also known as Kanna is also gaining traction. These different compositions of the plant can be chewed, smoked, snorted or swallowed resulting in increased libido, decreased stress, euphoria and appetite suppression. There are reports attributing the antidepressant and mood-elevating effects of the plant to the serotoninergic activity of its alkaloids including mesembrenone, mesembrenol, mesembrine, and tortuosamine. Indiscriminate use has been associated with the development of anxiety, headache, hypertension, irritability, insomnia and nausea[154,155]. A serotonin syndrome has also been observed especially when consumed alongside selective serotonin reuptake inhibitors or monoamine oxidase inhibitors. Although the use of a number of these plants and herbs may not be illegal in the countries in which they are consumed, increasing reports of poisoning arising from the use or these psychoactive plants solely or in combination with other compounds is drawing attention to the need to enact public health laws that can criminalize their use.

Synthetic cannabinoid in herbal products

Synthetic cannabinoids are compounds which are structurally similar to natural cannabinoids [tetrahydrocannabinol and cannabidiol ( CBD)] allowing them to exert their effect through binding to cannabinoid receptors (CBD1 and CBD2)[156,157]. Synthetic cannabinoids can be agonists at the CB₁ receptors or antagonists at other cannabinoid receptors. Although many of the synthetic cannabinoids are used in pharmacology in structure - activity relationships and receptor binding studies, others have medicinal uses including in the treatment of anorexia, as antiemetics in cancer chemotherapy and in pain management. In the last two decades, commercial preparations containing synthetic cannabinoids have become popular for their use as designer drugs marketed as herbal incense or herbal blends under the names ‘Spice’, ‘synthetic marijuana’, and ‘K2’[158-160]. The cannabinoid compound is sprayed onto inert plant material and smoked or ingested in liquid form[160,161]. Although often considered legal and safe alternatives to cannabis, there is evidence indicating that synthetic cannabinoids use is associated with significant health risks when compared to marijuana; there have also been reports that their distinct pharmacological effects and metabolic activity could also be a contributing factor to the increased toxicity observed following their use[157,162,163].

To date, the abuse of herbal preparations that have been spiked with synthetic cannabinoids continues to increase. This is evidenced by an increasing list of commercial preparations marketed in the United States and Europe under the names fairly legal, Pandora’s box, Angry birds, exodus, bonzai, annihilation, weekend blend, fire, strong spice, green Buddha, smoke, and Scooby snacks[102,164]. In the last few years, Africa is also beginning to experience a surge in demand for and use of synthetic cannabinoids. In Mauritius, since the year 2015, there has been a reported increase the number of arrests involving synthetic cannabinoids[165]. In different countries in the continent they are marketed under various street names including, Wiz in South Africa[166]. In Nigeria it is marketed as Black Mamba, Colorado, Lamba, Happy Boy or Scooby Snax[167].

Across Africa, available evidence points to a growing use of novel psychoactive compounds which mainly contain synthetic cannabinoids. Synthetic cannabinoids have effects that are similar to that experienced with natural cannabis, although they are more potent and have been associated with more severe physical and psychological adverse effects necessitating hospitalizations[168,169].

PREVALENCE OF SUBSTANCE USE DISORDERS AND AVAILABILITY OF EVIDENCE-BASED TREATMENT CENTRES IN AFRICA

Substance use disorders are defined as the persistent use of alcohol or other psychoactive substances despite significant harm and untoward health consequences[170]. They are characterized by an array of social, emotional and behavioral problems. Across Africa, there is also a dearth of scientific data on the prevalence of substance use disorders or drug dependence[48,55,56,171]. In Nigeria, reports from the 2018 National Drug Survey revealed that one in every five persons who used drug in the past year also had a drug-related disorder[48,55,56]. In South Africa, results obtained from a nationally representative sample of 4351 persons aged 18 years and above revealed a lifetime prevalence of substance use disorders of 13%, with alcohol use disorder being the most prevalent type of substance use disorders[72,171-173]. In Egypt, reports obtained from the National Addiction Research Study revealed the prevalence of drug dependence in the different regions ranged from 3.2%-9.3%[174].

Left untreated, substance use disorders contribute significantly to the global burden of disease, including increasing morbidity and mortality and societal cost implications such as increased healthcare costs, lost productivity and costs related to social welfare and criminal justice[4,5]. Access to evidence-based treatment has been linked with a reduction in the risk for ill health[171]. Accordingly, towards reducing the burden of substance use globally, availability and access to evidence-based treatment facility were included in the United Nations’ Sustainable Development Goals for 2030[175]. However, despite reports of increasing prevalence of drug dependence and substance use disorders, reports from surveys carried out in a number of countries in Africa suggest that the availability of treatment centers are limited[171,176]. Factors contributing to this treatment gap include treatment infrastructure constraints, poor funding, and the high cost of private-for-profit treatment centers[171,176].

How can Africa’s burgeoning substance use and substance use disorder problem be addressed

It has become evident that there is a burgeoning illicit drug use problem across the African continent[47-49,177]. There had been predictions that by the year 2050, increased life expectancy and a rapidly growing population would result in approximately 130% increase in the burden of mental and substance use disorders to about 45 million years lived with disability in Africa[178]. While different factors, including increased access to illicit drugs and high level of youth unemployment have been adduced to explain the emerging drug use pandemic; its significant contribution to economic instability, crime, criminality and insecurity across Africa and worldwide means that governments and policy makers need to prioritize the need to develop ways to mitigate these problems. The dearth of comprehensive data and the uniqueness of the manifestation of illicit drug use to individual countries within the African region are factors that impede progress towards addressing this looming pandemic.

Understanding the different determinants of drug use within the different populations of Africans and how these impact the prevention and treatment of substance abuse disorders in the individual countries would be an important step towards addressing this emerging pandemic. Currently available data suggests that influencers of drug use (particularly in adolescents) which include family, social networks and peer pressure are common to most of the countries[179-184]. Other determinants of drug use also include childhood trauma and adverse life experiences such as sexual, emotional or physical abuse. Across age groups, demographic factors such as being male, lower level of education and attendance of private schools have also been reported by researchers from the different regions of Africa[185-187].

In addition to understanding the influencers and determinants of drug use, there is also a need for up-to-date national and regional data that can adequately determine the prevalence and incidence of drug use across all demographics. The availability of a detailed and comprehensive national data would provide a background against which policy successes or failures can be measured, it would also alert governments and international partners on the need for increased funding or more treatment facilities.

The deleterious health effects of drug use disorders means that the provision of effective prevention, treatment and care facilities for substance use disorders is a necessary investment in the health of the society as a whole. Research has shown that the availability of evidence based prevention programs and policies have the ability to significantly reduce substance use and related harmful effects[188]. Behavioral and medication-assisted treatment using a chronic-illness-management approach has also been shown to aid recovery and prevent relapse. There have been suggestions that easy access to support services assist previous substance users to achieve and maintain wellness long-term[188].

Addressing the ease of access to drugs and other illicit substances within communities and regions need to be taken more seriously. There is a need to gather information on the different types of novel psychoactive substances that are available within communities and also create awareness as to the adverse health effects associated with consuming these compounds.

Limitations and recommendations

One of the major limitations encountered in this review was the dearth of recent, community based and age specific scientific data on the prevalence and extent of the substance abuse problems in most of the countries in Africa. There was also a deficit of data on the details and impact of the country-specific intervention protocols. This led to reliance mainly on third party data from international; partners and a few independent researchers. The battle to win this emerging substance–use pandemic in Africa can only be successful if there is increased emphasis in documenting the extent of the problem and country specific interventions; particularly at the community levels with emphasis on how different age groups are impacted by substance abuse.

CONCLUSION

In Africa, substance use and substance use disorders drain struggling economies and health care systems. While the continent might have some general idea of what it is up against, understanding the details of the problem and availability of the willpower/wherewithal to subdue it remains a challenge. It is becoming obvious that there is no substitute for well-designed, accurate and comprehensive population-focused efforts at obtaining data that relates to substance use and substance use disorders, since such data will form the foundations for designing effective intervention strategies. Also, in Africa, interventional strategies should place emphasis on prevention, through identification of and mitigation of risk factors, as this approach is likely to consume less resources in the long run.