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Adults with ADHD represent an important subgroup of OCD

Adult patients with obsessive-compulsive disorder and ADHD experienced earlier onset of and more severe obsessive-compulsive symptoms, according to a large cross-sectional study.

“Recent findings suggest that OCD and ADHD could share common genetic predisposition factors or be associated with dysfunctions in similar neurotransmitter pathways,” Thiago BlancoVieira, PhD, from the department of psychiatry, Federal University of São Paulo, Brazil, and colleagues wrote. “In adults ... the presence of ADHD in OCD subjects has been rarely investigated and few studies have examined possible correlates of this comorbidity.”

Researchers conducted a crosssectional study of 955 adult patients with OCD from the Brazilian Research Consortium of ObsessiveCompulsive Spectrum Disorders. They compared clinical characteristics in adult OCD patients with and without comorbid ADHD and identified characteristics independently related to ADHD comorbidity.

Overall, 131 patients (13.7%) had comorbid ADHD. Of these, 15 patients (11.5%) reported using methylphenidate at some point and 77 patients (8%) had a diagnosis of Tourette’s syndrome. Blanco-Vieira and colleagues found that adults with OCD and ADHD:

• were younger;
• had earlier age of obsessive-compulsive symptom onset;
• increased risk for academic impairment;
• greater history of rheumatic fever;
• higher current and past total The Dimensional YaleBrown ObsessiveCompulsive Scales (DY-BOCS) severity;
• higher symptom severity in most DY-BOCS dimensions;
• greater frequency of sensory phenomena;
• higher number of current and lifetime comorbidities;
• increased rate of Tourette’s syndrome;
• greater anxiety and depression symptom severity; and
• more suicide attempts.

In logistic regression analysis, medical history of rheumatic fever (OR = 3.45; P = .001), Tourette’s syndrome (OR = 2.31; P = .003), sensory phenomena (OR = 1.93; P = .006); school grade retention (OR = 1.65; P < .0001); higher anxiety scores (OR = 1.03; P < .0001); and younger age of obsessive-compulsive symptom onset (OR = 0.95; P = .011) remained significantly linked to ADHD comorbidity.

“The current results reinforced our main hypothesis demonstrating the negative impact of ADHD on the clinical presentation of OCD and the relevance of addressing this comorbidity,” the researchers wrote. “Future studies may try to develop more tailored interventions for these patients as OCD patients with comorbid ADHD present some specific and relevant clinical features.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.