Comorbidities are commonly associated with attention-deficit hyperactivity disorder (ADHD) in children, adolescents and adults. 

The European ADORE (Attention-deficit/hyperactivity Disorder Observational Research in Europe) study of clinically referred children (n=1478; mean age girls=8.8 years, boys=9.0 years) found that children and adolescents with ADHD had substantial “co-existing psychiatric disorders”, the most common being oppositional defiant disorder (67%), and conduct disorder (46%) (Figure).1,2 The ADORE study did not perform a detailed assessment of the psychiatric disorders co-existing with ADHD, but rather collected overall clinical ratings of the disorders, which may, in part, explain the high prevalence rates.2

Co-existing psychiatric disorders associated with ADHD in children and adolescents in the ADORE study2

Co-existing psychiatric disorders associated with ADHD in children and adolescents in the ADORE study
The comorbidity profile across the sample of this study was similar between genders,3 and the study also found that the presence of multiple psychiatric comorbidities impacted overall health-related quality of life more than the presence of ADHD alone.2

Various other studies have characterised the comorbidity profile of adults with ADHD:

  • A population-based survey of adult twins born in Sweden (n=17,899) found that symptoms of ADHD were associated with an increased risk for symptoms of generalised anxiety disorder (odds ratio [OR]: 5.6), major depression (OR: 2.8), bipolar disorder (OR: 8.0), obsessive-compulsive disorder (OR: 3.9) and alcohol dependence (OR: 2.6), with no significant difference between genders4
  • A Spanish, multi-centre, observational study of newly diagnosed adults with ADHD (n=376) found that on average, 2.4 comorbidities were present at the time of first diagnosis, and that 66.2% of the sample had at least one psychiatric comorbidity5
  • The most common comorbidities in a US study of adults with ADHD (n=3199) included social (29.3%) and specific (22.7%) phobia, bipolar disorder (19.4%), major depressive disorder (18.6%), intermittent explosive disorder (19.6%) and substance use disorder (alcohol/drugs) (15.2%).6

Impact on quality of life

Patients with both ADHD and comorbidities may experience greater impairment in their lives than those with ADHD alone, with one study reporting that children with ADHD and comorbid social/emotional problems (such as depression, anxiety and phobias) have higher rates of school absenteeism and healthcare utilisation, than those with ADHD alone.7 Furthermore, in a study of adults (n=414) with ADHD, a history of comorbid substance abuse, anxiety or depression was correlated with unemployment.8

Treatment response

As comorbidity groups differ in their response to treatment and outcomes, the evaluation and diagnosis of comorbidities are essential for the development of an effective treatment plan, to avoid sub-optimal management and to reduce the likelihood of adverse social and emotional outcomes associated with ADHD.9-11


View references

  1. Preuss U, Ralston SJ, Baldursson G, et al. Study design, baseline patient characteristics and intervention in a cross-cultural framework: results from the ADORE study. Eur Child Adolesc Psychiatry [Suppl1 ] 2006; 15: 1/4–1/14.
  2. Steinhausen HC, Nøvik TS. ADORE Study Group. Co-existing psychiatric problems in ADHD in the ADORE cohort. Eur Child Adolesc Psychiatry 2006; 15(Suppl 1): i25-i29.
  3. Nøvik TS, Hervas A, Ralston SJ, et al. Influence of gender on attention-deficit/hyperactivity disorder in Europe--ADORE. Eur Child Adolesc Psychiatry 2006; 15(Suppl 1): I15-I24.
  4. 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.
  5. Piñeiro-Dieguez B, Balanzá-Martínez V, García-García P, et al. Psychiatric Comorbidity at the Time of Diagnosis in Adults With ADHD: The CAT Study. J Atten Disord 2014; 1-10.
  6. 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.
  7. Classi P, Milton D, Ward S, et al. Social and emotional difficulties in children with ADHD and the impact on school attendance and healthcare utilization. Child Adolesc Psychiatry Ment Health 2012; 6: 33.
  8. Halmoy A, Fasmer OB, Gillberg C, et al. Occupational outcome in adult ADHD: impact of symptom profile, comorbid psychiatric problems, and treatment: a cross-sectional study of 414 clinically diagnosed adult ADHD patients. J Atten Disord 2009; 13: 175-187.
  9. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. 2013.
  10. NICE (2008) Attention Deficit Hyperactivity Disorder: Diagnosis and Management of ADHD in Children, Young People and Adults. NICE clinical guideline 72. Available at [NICE guideline]. Last accessed May 2015.
  11. Taylor E, Döpfner M, Sergeant J, et al. European clinical guidelines for hyperkinetic disorder – first upgrade. Eur Child Adolesc Psychiatry 2004; 13 Suppl 1: i7-i30.

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Comorbidities should be taken into account when diagnosing patients and planning treatment

Read article by Prof Banaschewski