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

Table 2 Included relevant articles examining attention-deficit/hyperactivity disorder and suicidality from January 2011 to January 2015: Suicidality in patiens with attention-deficit/hyperactivity disorder

Suicidality in patiens with ADHD
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
Barbaresi et al[29]	United States	Cross-sectional	Community sample	Adults with childhood ADHD: n = 232 Non-ADHD controls: n = 335	ADHD group: Mean age: 27 yr Non-ADHD group: Mean age: 28.6 yr	MINI	The rate of death from suicide was significantly higher among adults with childhood ADHD compared to non-ADHD adults
Cheng et al[30]	Taiwan	Cross-sectional	Community sample	5405 University students: n = 5405 (male ratio: 64.8%) ADHD symptoms were elevated in 8.6% of the sample: (male ratio: 75.1%)	University students	ASRS, BSRS-5	Individuals with higher levels of ADHD symptoms were more likely to have higher suicidal ideation
Huntley et al[31]	United Kingdom	Cross-sectional	Clinical Sample	Participants from two in-patient alcohol and drug detoxification units: n = 226 (male ratio: 76.5%) Patient with alcohol/drug intoxication + ADHD: n = 11 Patient with alcohol/drug intoxication without ADHD: n = 183	Mean age: 39.0 yr (SD = 10.3)	DSM-IV 18-item self-report ADHD screening questionnaires for both current and childhood behavior Impairment questions from the Barkley scales DIVA	Patients with both substance use disorders and ADHD had significantly higher rates of prior suicide attempts than patients with substance use disorder without ADHD
Hurtig et al[32]	Finland	Longitudinal: 16 yr. First follow up: at ages 7, 8, second follow up at ages 15, 16	Community sample	ADHD adolescents: n = 104 Non-ADHD adolescents: n = 169	Adolescents from the same birth cohort	At 8 yr of age: Rutter B2 During the 15-16 yr follow up: SWAN, K-SADS-PL	Adolescents with ADHD had more suicide ideation, acts than adolescents without ADHD. The effect of ADHD on suicidal ideation remained strong after controlling for other variables
Kavakci et al[33]	Turkey	Cross-sectional	Community sample	980 university students (male ratio: 55.9%) ADHD: n = 48 Non-ADHD: n = 932	Age range: 17-44 yr Mean age: 21.4 yr (SD = 2.3 yr)	ASRS SCID I, SCID II, Adult ADHD Module of MINI Plus	Adolescents with ADHD reported significantly more lifetime suicide attempts than those without ADHD
Keresztény et al[34]	Hungary	Cross-sectional	Clinical sample	Children: n = 168 (male ratio: 87.5%) Adolescents: n = 43 (male ratio: 62.8%)	Children: Age range: 3-12 yr Mean age: 8.23 yr (SD = 2.22) Adolescents: Mean age: 14.65 yr (SD = 1.6 yr) boys: 27 (62.8%)	MINI-KID	The most common comorbid diagnoses with ADHD were oppositional defiant disorder, conduct disorder and suicide behavior in both age-groups. The rate of suicide behavior was 17% among children and 58% among adolescents
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. Those, who had ADHD + co-occurring sadness and ODD, 46% had ideation and 21% had attempts
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	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 Questionnair, 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
Van Eck et al[40]	United States	Cross-sectional	Community sample	Undergraduate psychology students: n = 627 (male ratio: 40%)	Mean age: 20.23 yr (SD = 1.40)	CSS BSI	ADHD indirectly increased suicidal ideation through depression. The moderator factors in the indirect effect of ADHD on suicidal ideation were emotion regulation deficits of accepting negative emotions, emotional awareness, and goal-oriented 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; PBS: Pediatric Behavior Scale; MINI: Mini-International Neuropsychiatric Interview; ASRS: Adult Self-Report Scale; BSRS-5: Brief Symptoms Rating Scale; DIVA: Diagnostic Interview for ADHD in Adults; SWAN: Strengths and Weaknesses of ADHD symptoms and Normal Behaviors; SCID-I: Structured Clinical Interview for DSM-IV Axis I Disorders; ODD: Oppositional defiant disorder; K-CIDI: Korean version of Composite International Diagnostic Interview; SNAP-IV: Swanson, Nolan, and Pelham Rating Scale; SIQ: Self-Injury Questionnaire; DISC-IV-YA: Diagnostic Interview Schedule for Children 4^th ed., Young Adult version; ADHD-C: ADHD combined type; ADHD-I: ADHD inattentive type, ADHD-HKS Questionnaire.