What are the most common comorbid psychiatric disorders associated with ADHD?
In a study of 2447 children and adolescents (aged 5–17 years) with ≥1 psychiatric disorder(s), 650 (27%) were diagnosed only with ADHD and 401 (16%) only with another psychiatric disorder, while 1396 (57%) had ≥2 psychiatric disorders (1269 [66%] also had ADHD). The prevalence of psychiatric comorbidities in children and adolescents with and without ADHD are presented in Figure 1.1
Figure 1: Psychiatric comorbidities in children and adolescents with and without ADHD. Reproduced with permission from Reale L et al. Eur Child Adolesc Psychiatry 2017; 26: 1443-1457.1
The US National Comorbidity Survey Replication found that adult Diagnostic and Statistical Manual of Mental Disorders – 4th Edition (DSM-IV) ADHD was highly comorbid with many other DSM-IV disorders in a large subsample of 18–44-year-olds (n=3199) in the US (Figure 2).2,3
Figure 2: Overall prevalence of ADHD and selected psychiatric comorbidities in the US National Comorbidity Survey Replication. Figure adapted from Kessler RC et al. Am J Psychiatry 2006; 163: 716-723.2
The lifetime prevalence for psychiatric disorders (such as anxiety disorders, bipolar disorder, major depressive disorder and substance-use disorders) has been shown to be significantly higher in males and females with DSM-IV ADHD than those without ADHD (p<0.05 for each).4
The majority of adults with ADHD have a diagnosed or undiagnosed comorbid psychiatric disorder, which can complicate diagnosis and treatment of ADHD.5-7
Are there any variations in the prevalence of psychiatric comorbidities in relation to different subtypes of ADHD?
Several studies have investigated the variation in prevalence of psychiatric comorbidities in relation to different ADHD subtypes.8-10
- A study using the Swedish Twin Registry reported lower risks of generalised anxiety disorder and major depression for hyperactive-impulsive subtype ADHD compared with combined and inattentive subtypes.8
- A US-based study evaluated patterns of comorbidity associated with the different subtypes of ADHD. The majority of subgroup differences demonstrated that individuals with combined subtype ADHD reported more severe comorbid symptoms versus hyperactive-impulsive and inattentive subtypes.9
- A study of adult outpatients with ADHD reported higher rates of antisocial disorder, bipolar disorder, lifetime conduct disorder, major depression, psychosis and substance dependence in adults with combined subtype ADHD compared with the inattentive and hyperactive subtype.10
Are there any sex differences between ADHD and certain psychiatric comorbidities?
Some studies suggest that there are sex differences between ADHD and certain psychiatric comorbidities11,12; however, other studies have reported no such differences when investigating some psychiatric comorbidities.8,12
Evidence showing differences between men and women
- A Norwegian study reported significant differences between men and women with ADHD for the frequency of affective disorders (28% vs 49%, respectively), eating disorders (0% vs 6%, respectively) and dyslexia (9% vs 4%, respectively).11
- A cross-sectional study found significant differences between men and women with ADHD for the frequency of comorbid alcohol dependence (10.0% vs 4.0%, respectively), substance abuse (5.2% vs 0.7%, respectively), substance dependence (23.6% vs 9.4%, respectively) and bulimia/anorexia (1.1% vs 13.0%, respectively).12
Evidence showing no differences between men and women
- A large, Swedish, population-based study reported no significant difference between sex in the increased risks of symptoms of alcohol dependence, bipolar disorder, generalised anxiety disorder, major depression and obsessive-compulsive disorder in 227 adults with DSM-IV ADHD.8
- A cross-sectional study also reported no significant differences between sexes of individuals with ADHD across agoraphobia, alcohol abuse, bipolar disorder, generalised anxiety disorder, major depression, obsessive-compulsive disorder, panic disorder, post-traumatic stress disorder, psychotic disorder, social phobia and suicidality.12
- Reale L, Bartoli B, Cartabia M, et al. Comorbidity prevalence and treatment outcome in children and adolescents with ADHD. Eur Child Adolesc Psychiatry 2017; 26: 1443-1457.
- Kessler RC, Adler L, Barkley R, et al. The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication. Am J Psychiatry 2006; 163: 716-723.
- Kessler RC, Berglund P, Chiu WT, et al. The US National Comorbidity Survey Replication (NCS-R): design and field procedures. Int J Methods Psychiatr Res 2004; 13: 69-92.
- Biederman J, Petty CR, Monuteaux MC, et al. Adult psychiatric outcomes of girls with attention deficit hyperactivity disorder: 11-year follow-up in a longitudinal case-control study. Am J Psychiatry 2010; 167: 409-417.
- NICE guideline 2018. Attention deficit hyperactivity disorder: diagnosis and management. Available at: https://www.nice.org.uk/guidance/ng87. Accessed January 2021.
- Canadian ADHD Resource Alliance (CADDRA). Canadian ADHD Practice Guidelines. Edition 4.1. Toronto, ON: CADDRA, 2020.
- Kooij JJS, Bijlenga D, Salerno L, et al. Updated European Consensus Statement on diagnosis and treatment of adult ADHD. Eur Psychiatry 2018; 56: 14-34.
- Friedrichs B, Igl W, Larsson H, et al. Coexisting psychiatric problems and stressful life events in adults with symptoms of ADHD–a large Swedish population-based study of twins. J Atten Disord 2012; 16: 13-22.
- Sprafkin J, Gadow KD, Weiss MD, et al. Psychiatric comorbidity in ADHD symptom subtypes in clinic and community adults. J Atten Disord 2007; 11: 114-124.
- Wilens TE, Biederman J, Faraone SV, et al. Presenting ADHD symptoms, subtypes, and comorbid disorders in clinically referred adults with ADHD. J Clin Psychiatry 2009; 70: 1557-1562.
- Rasmussen K, Levander S. Untreated ADHD in adults: are there sex differences in symptoms, comorbidity, and impairment? J Atten Disord 2009; 12: 353-360.
- Anker E, Bendiksen B, Heir T. Comorbid psychiatric disorders in a clinical sample of adults with ADHD, and associations with education, work and social characteristics: a cross-sectional study. BMJ Open 2018; 8: e019700.