Stimulants, including methylphenidate and amphetamines, are the first-line pharmacological treatment of ADHD in adults. However, in patients who do not respond or poorly tolerate stimulants, non-stimulant medications are usually recommended.

The authors provide a narrative review of the literature on non-stimulant treatments for adult ADHD, including controlled and observational clinical studies conducted on adult samples. Atomoxetine has been extensively studied and showed significant efficacy in treating adult ADHD. Issues related to dosing, treatment duration, safety, and use in the case of psychiatric comorbidity are summarized. Among other compounds indicated for ADHD in adults, antidepressants sharing at least a noradrenergic or dopaminergic component, including tricyclic compounds, bupropion, and viloxazine, have shown demonstratable efficacy. Evidence is also available for antihypertensives, particularly guanfacine, as well as memantine, metadoxine, and mood stabilizers, while negative findings have emerged for galantamine, antipsychotics, and cannabinoids.

While according to clinical guidelines, atomoxetine may serve as the only second-line option in adults with ADHD, several other nonstimulant compounds may be effectively used in order to personalize treatment based on comorbid conditions and ADHD features. Nevertheless, further research is needed to identify and test more personalized treatment strategies for adults with ADHD.

Prescription stimulants are often used to treat attention deficit hyperactivity disorder (ADHD). Drugs like methylphenidate (Ritalin, Concerta), dextroamphetamine (Dexedrine), and dextroamphetamine-amphetamine (Adderall) help people with ADHD feel more focused. However, misuse of stimulants by ADHD and nonaffected individuals has dramatically increased over recent years based on students' misconceptions or simple lack of knowledge of associated risks. In this review, we discuss recent advances in the use and increasing misuse of prescription stimulants among high school and college students and athletes. Given the widespread belief that stimulants enhance performance, there are in fact only a few studies reporting the cognitive enhancing effects of stimulants in ADHD and nonaffected individuals. Student athletes should be apprised of the very serious consequences that can emerge when stimulants are used to improve sports performance. Moreover, misuse of stimulants is associated with dangers including psychosis, myocardial infarction, cardiomyopathy, and even sudden death. As ADHD medications are prescribed for long-term treatment, there is a need for long-term safety studies and education on the health risks associated with misuse is imperative.

Stimulant medications are the most effective drugs in the treatment of attention-deficit hyperactivity disorder (ADHD) in children and in adults. However, some patients do not respond to this treatment and other patients suffer from adverse effects. Very often there are also comorbid disorders that warrant treatment or there is somatic comorbidity that precludes the prescription of stimulants. As a result, alternative treatments for the treatment of ADHD have been explored, such as antidepressant agents. In this systematic review the evidence base for the effect of antidepressants for ADHD in adult patients is determined.

Electronic and hand searches were conducted in order to identify clinical trials studying antidepressants for the treatment of ADHD in adult patients. The trials were screened for methodological characteristics and treatment-effect sizes. The odds ratio was calculated for randomized controlled trials with bupropion. A descriptive review of all the randomized controlled studies and an overview of the nonrandomized studies was developed.

Only eight randomized controlled trials were retrieved with four different compounds. Five studies concerned bupropion and the meta-analysis indicates a beneficial effect for bupropion compared with placebo as measured with the Clinical Global Improvement Scale (odds ratio 2.42 [95% CI 1.09 to 5.36]). Several studies suffer from clinical and methodological shortcomings, such as exclusion of patients with comorbid disorders, short treatment duration, or a lack of information with respect to the randomization procedure.

Although there is a need for alternative interventions for the treatment of ADHD, such as with antidepressant agents, the evidence base is not large. Only treatment with bupropion seems to have a medium-range effect size, but this is less than that of stimulant medications.

Recent investigations have shown that three major striatal-signaling pathways (protein kinase A/DARPP-32, Akt/glycogen synthase kinase 3, and ERK) are involved in the regulation of locomotor activity by the monoaminergic neurotransmitter dopamine. Here we used dopamine transporter knock-out mice to examine which particular changes in the regulation of these cell signaling mechanisms are associated with distinct behavioral responses to psychostimulants. In normal animals, amphetamine and methylphenidate increase extracellular levels of dopamine, leading to an enhancement of locomotor activity. However, in dopamine transporter knock-out mice that display a hyperactivity phenotype resulting from a persistent hyperdopaminergic state, these drugs antagonize hyperactivity. Under basal conditions, dopamine transporter knock-out mice show enhanced striatal DARPP-32 phosphorylation, activation of ERK, and inactivation of Akt as compared with wild-type littermates. However, administration of amphetamine or methylphenidate to these mice reveals that inhibition of ERK signaling is a common determinant for the ability of these drugs to antagonize hyperactivity. In contrast, psychostimulants activate ERK and induce hyperactivity in normal animals. In hyperactive mice psychostimulant-mediated behavioral inhibition and ERK regulation are also mimicked by the serotonergic drugs fluoxetine and 5-carboxamidotryptamine, thereby revealing the involvement of serotonin-dependent inhibition of striatal ERK signaling. Furthermore, direct inhibition of the ERK signaling cascade in vivo using the MEK inhibitor SL327 recapitulates the actions of psychostimulants in hyperactive mice and prevents the locomotor-enhancing effects of amphetamine in normal animals. These data suggest that the inhibitory action of psychostimulants on dopamine-dependent hyperactivity results from altered regulation of striatal ERK signaling. In addition, these results illustrate how altered homeostatic state of neurotransmission can influence in vivo signaling responses and biological actions of pharmacological agents used to manage psychiatric conditions such as Attention Deficit Hyperactivity Disorder (ADHD).

Atomoxetine (Strattera) is a selective norepinephrine reuptake inhibitor and nonstimulant that has shown greater efficacy than placebo in attention deficit hyperactivity disorder (ADHD) in adults. In two large, well controlled, 10-week trials in adults with ADHD, improvements in ADHD symptoms, as assessed by investigator- and patient-rated scores, were greater with oral atomoxetine (60, 90 or 120 mg/day) than with placebo. Mean reductions in the total ADHD symptom score on the investigator-rated Conners' Adult ADHD Rating Scale (CAARS) in atomoxetine versus placebo recipients were 28.3% versus 18.1% and 30.1% versus 19.6%, respectively. Mean reductions in the scores on the Clinician Global Impression of Severity Scale, patient-rated CAARS and Wender-Reimherr Adult Attention Deficit Disorder Scale were also significantly greater with atomoxetine than with placebo. Continued efficacy was demonstrated in a noncomparative, 34-week extension phase. Atomoxetine was generally well tolerated in clinical trials; withdrawal rates due to adverse events in atomoxetine-treated versus placebo-treated patients participating in the two major trials were 7.8% versus 4.3% and 9.3% versus 2.4% (p<0.05 for the latter trial). Adverse events reported significantly more frequently with atomoxetine than placebo included dry mouth, insomnia, nausea, decreased appetite, constipation, dizziness, sweating, dysuria, sexual problems and palpitations. Modest increases in heart rate and blood pressure were well tolerated and gradually decreased on cessation of treatment. Atomoxetine was not associated with QT interval prolongation. Atomoxetine can be administered once or twice daily. Its subjective-effects profile is different to that of methylphenidate and atomoxetine is not associated with abuse or diversion; it is therefore not a controlled substance in the US. This also means repeat prescriptions during long-term treatment can be more conveniently processed.

Atomoxetine is an effective and generally well tolerated treatment for adults with ADHD. It is a nonstimulant and is the first ADHD treatment to be approved specifically for adult use based on its efficacy in well controlled adult trials. It can be administered as a single daily dose or split into two evenly divided doses. It carries negligible risk of abuse or diversion and is not a controlled substance. Atomoxetine is a valuable new treatment option for adults with ADHD and is particularly useful in patients who are at risk for substance abuse or who do not wish to take a controlled substance.