Attention-deficit/hyperactivity disorder and suicide: A systematic review

Table 4 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Suicidality in attention-deficit/hyperactivity disorder patients who have psychiatric comorbidity

Suicidality in ADHD patients who have psychiatric comorbidity
Ref.	Country	Study design	Sample	Population at onset	Population’s age at onset	Measures for ADHD, comorbid conditions and suicidality	Main findings
Agosti et al[27]	United States	Cross-sectional	Clinical sample	Current ADHD: 365 adults: With Suicide attempts: n = 59 No suicide attempts: n = 306	Age range: 18-66 yr	CIDI, ACDS, DIS-IV	Sixteen percentage of participants with current ADHD diagnosis had previous suicide attempt. While ADHD increased the risk of previous suicide attempt only 1.5 fold, having one or more comorbid disorders increased the risk of previous suicide attempt 4 to 12 fold
Balazs et al[28]	Hungary	Cross-sectional	Clinical sample	ADHD and subthreshold ADHD children: n = 220 ADHD and subthreshold ADHD adolescents: n = 198	Children: Age range: 3-11 yr Mean age: 7.67 yr (SD = 2.03) Adolescents: Age range: 12-17 yr Mean age: 14.31 yr (SD = 1.67)	MINI-KID	The relationship between ADHD and suicidality was fully mediated by comorbid psychiatric disorders. In children, symptoms of anxiety disorders mediated this relationship, while in the adolescent group, symptoms of major depressive episode, dysthymia, and substance abuse/dependence were found to be significant mediators
Daviss et al[47]	Lebanon	Cross-sectional	Clinical sample	Youth with ADHD: n = 101 (male ratio: 63.4%) Lifetime SBs n = 28 (male ratio: 42.9%) No lifetime SBs: n = 73 (male ratio: 71.2%)	Age range in the whole sample: 11-18 yr Lifetime SBs: Mean age: 14.6 yr (SD = 2.1) No lifetime SBs: Mean age: 13.5 yr (SD = 1.8)	K-SADS-PL ADHD Rating Scale	In this ADHD sample, after controlling for the age, female sex, and comorbid disorders, lifetime SB remained significantly associated with parent-child conflict, and impairment in nonacademic domains of function and breadth of exposure to victimization events Past and current ADHD symptoms and signs were not associated with lifetime SB
Ljung et al[35]	Sweden	Cross-sectional	Patient and prescribed drug registers and population-based registers	ADHD: n = 51707 (male ratio: 69.8%) Control: n = 258535	Age range: 3-40 yr	Discharge diagnosis of ADHD	Participants with ADHD had an increased risks of both attempted and completed suicide compared with control participants. This result was the same even after adjusting for comorbid psychiatric conditions. While the highest familial risk was reported among first-degree relatives, lower risk was observed among more genetically distant relatives. The results suggests that shared genetic factors are important for this association
Mayes et al[36]	United States	Cross-sectional	Community and clinical sample	1706 children and adolescents with psychiatric disorders and typical development: ADHD-C: n = 566 (male ratio: 74.6%) ADHD-I: n = 235 (male ratio: 57.4%) Other psychiatric disorders (autism, depression/ anxiety, eating disorder, intellectual disability): n = 719 (male ratio: 67.2%) Typical: n = 186 (male ratio: 43.5%)	Age range: 6-18 yr	All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS	All psychiatric groups had far more suicide behavior than typically developed children. ADHD-C: 20.7% had suicide ideation, 6.0% attempt ADHD-I: 7.3% had suicide ideation, 2.6% attempt
Mayes et al[37]	United States	Cross-sectional	Clinical sample	Children and adolescents with ADHD: n = 925 (male ratio: 68.5%) ADHD-C: n = 666 ADHD-I: n = 259	Age range: 3-16 yr Mean age: 8.8 yr (SD = 2.6)	All participants had a clinical diagnosis of ADHD made by a licensed PhD psychologist. The clinical diagnosis was based on a comprehensive psychological evaluation including diagnostic inter- views with the parent and child, parent and teacher rating scales, review of educational and medical records, extensive psychological testing PBS - suicide ideation and attempt items	For the total sample with ADHD, 15.8% had suicide ideation (sometimes or more) and 5.5% had attempts. Ideation and attempts were more than twice as prevalent among participants with ADHD-C than among participants with ADHD-I. ADHD-C: 19% had suicide ideation, 7% attempt ADHD-I: 7% had suicide ideation, 3% attempt Those, who had ADHD alone: 6% had suicide ideation and 2% had suicide attempt
Park et al[38]	South Korea	Cross-sectional	Community sample	A total of 6081 subjects: Non-ADHD symptom group: n = 6012 ADHD symptom group: n = 69	Age range: 18-59 yr	K-CIDI Adult ADHD Self-Report Scale	Those, who had ADHD + co-occurring sadness and ODD, 46% had ideation and 21% had attempts Adult ADHD symptoms are significantly associated with lifetime suicidality. However, the association disappeared after adjusting for other comorbid psychiatric disorders
Swanson et al[39]	United States	Longitudinal: 10 yr: First 5 yr follow up and second 10 yr follow-up	Community and clinical sample	ADHD girls: n = 140 Non-ADHD girls: n = 88	Age range: 6-12 yr at ascertainment Mean age at 5 yr follow-up: 14.2 yr Mean age at 10 yr follow-up: 19.6 yr (range 17-24 yr)	At ascertainment: DISC-IV First follow up: SNAP-IV, Second follow up: SIQ, Barkley Suicide Questionnaire, DISC-IV-YA	Women with a childhood diagnosis of ADHD-C, compared with those with ADHD-I and control group, were at higher risk for suicide attempts. Furthermore, women with a persistent ADHD diagnosis were at higher risk than women with a transient diagnosis and the control group
Taylor et al[48]	New Zealand	Cross-sectional	Community sample	66 adults (43 men, 23 women ADHD: n = 35 (male ratio: 65.7%) Non-ADHD: n = 31 (male ratio: 64.5%)	Age range: 18-65 yr Mean age: 31.9 yr (SD = 1.6)	CAARS DSHI SCID-I (suicidality) CAADID	There was a significant associations between ADHD symptom severity and self-reported suicidal ideation and suicide attempts. These associations between suicidal behaviours and ADHD symptom severity were significantly and differentially mediated by psychosocial variables such as comorbidities (mood, anxiety, drug, and alcohol abuse disorders) and emotion-focussed coping style

SB: Suicidal behavior; ADHD: Attention-deficit/hyperactivity disorder; CIDI: Composite International Diagnostic Interview; ACDS: Adult ADHD Clinical Diagnostic Scale; DIS-IV: The Diagnostic Interview Schedule for DSM-IV; MINI-KID: Mini-International Neuropsychiatric Interview for children and adolescents; K-SADS-PL: Schedule for Affective Disorder and Schizophrenia for School-Age Children- Present and Lifetime Version; K-CIDI: Korean version of Composite International Diagnostic Interview; DISC-IV-YA: Diagnostic Interview Schedule for Children 4th ed., Young Adult version; SNAP-IV: Swanson, Nolan, and Pelham Rating Scale; SIQ: Self-Injury Questionnaire; CAADID: Conners’Adult ADHD Diagnostic Interview for DSM-IV; CAARS: Conners’ Adult ADHD Rating Scale; DSHI: Deliberate Self-Harm Inventory; ADHD-C: ADHD combined type; ADHD-I: ADHD inattentive type, ADHD-HKS Questionnaire.