In this expert Q&A, Julie Sherman, PhD and Jay Tarnow, MD briefly discuss the latest research findings on ADHD and answer the question, “What are common comorbidities in ADHD?”
Answer: ADHD is diagnosed in 3% to 5% of the US population.1 The risk for comorbidity with other disorders is high, and the presence of comorbid disorders warrants special consideration in the treatment of patients with this disorder. For example, a comorbid diagnosis of ADHD and depression occurs in approximately 20% to 30% of patients, and ADHD and anxiety in over 25% of patients.1
These comorbidity rates are equally or more prevalent in adults as they are in children, but very few studies have examined these patterns over time in adults. In a longitudinal study, Michielsen colleagues1 assessed older adults over a 6-year period for symptoms of ADHD, depression, and anxiety, and results revealed that ADHD was associated with higher risk for both depression and anxiety.
Some researchers propose that bipolar disorder (BD) and ADHD together should form a separate clinical phenotype of BD. A recent study examined BD in patients with ADHD and without ADHD.2 In addition to being screened for both disorders, patients were screened for mood, anxiety, eating, impulse control, alcohol(Drug information on alcohol), and substance use disorders. Results indicated that approximately 20% of adults with BD also had ADHD. Patients with BD and ADHD had higher rates of current mixed episodes, lower rates of mania, greater impairment overall, and greater levels of depression. Patients with BD and ADHD also had lower remission rates, greater rates of substance use disorders, and they reported greater levels of familial maladjustment than the BP alone adults.
ADHD is also associated with abnormalities in the frontal lobes. It makes sense that any neurological disorder originating in these regions would increase the risk for ADHD. Zhang and colleagues3 evaluated children with frontal lobe epilepsy for the prevalence of ADHD. Results found that 89.4% of children with abnormal electroencephalography (EEG) readings had a co-occurrence of ADHD, compared with only 25% of children with normal EEG readings. The authors concluded that frontal lobe epilepsy is strongly linked to the occurrence of ADHD, and this occurrence is even greater for individuals with an abnormal EEG.
It is important to treat all comorbidities to maximize treatment. Because individuals with comorbid psychiatric disorders experience greater cognitive, social, and psychological impairments, mental health professionals are encouraged to screen for early detection and intervention.