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ADHD associated with high rates of comorbid psychiatric disorders in children, adults of both sexes, studies show

Thursday, December 13 2007 | Comments

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What's This? Recent large studies have revealed that attention-deficit/hyperactivity disorder is associated with a host of comorbid psychiatric disorders, according to 3 researchers.

Dr. Joseph Biederman, chief of clinical and research programs in pediatric psychopharmacology and adult ADHD at Massachusetts General Hospital, reviewed the results of 2 long-term, prospective studies conducted in both boys and girls.

The studies used the same methodology and began with children aged 6 to 17 years with or without ADHD according to DSM-III-R and DSM-IV criteria. Overall, 140 boys and 140 girls had ADHD. He noted that the 242 control children were "not super normal," but did not have ADHD.

The subjects were first evaluated when they were aged approximately 10 to 12 years; girls were then followed for 5 years and boys were followed for 10 years.

By an average age of 17 years, 82% of females who had ADHD at baseline still had the disorder. The incidence of persistent ADHD in males was 70% at the average age of 22 years. At least 90% of both males and females with ADHD had received some form of treatment, mostly medication with or without counseling.

At follow-up, the boys with ADHD relative to those without ADHD had significantly higher rates of behavioral disorders, including conduct disorder (CD; P<.001), oppositional defiant disorder (ODD; P<.001), and antisocial personality disorder (P=.004). The rates of CD (P<.001) and ODD (P<.001) were also significantly higher in girls who had ADHD than in girls who did not at follow-up.

Dr. Biederman pointed out that while comorbid CD and ODD rates remained lower in girls than in boys, the rates grew rapidly in girls during adolescent follow-up. Boys tended to experience these disorders at younger ages.

Both boys and girls with ADHD also demonstrated significantly greater rates of major depressive disorder (MDD), bipolar disorder, and multiple anxiety disorders when compared with controls at follow-up; all rates nearly doubled among girls with ADHD during adolescence. MDD appeared to be mostly an early comorbidity in boys with ADHD. Girls with ADHD seemed to be more vulnerable to multiple anxiety disorders than were boys with ADHD at follow-up.

In terms of alcohol and substance use disorders, boys with ADHD showed significantly greater rates of alcohol use disorders (P=.009), drug use disorders (P=.036), and smoking (P<.001); these rates were approximately double those of controls at follow-up. Similarly, smoking (P<.001) and drug use disorders (P=.007) were significantly more common in adolescent girls with ADHD than in those without the condition.

Dr. Biederman summarized that the high morbidity associated with ADHD in children of both sexes highlights the importance of early recognition and prevention as well as early interventional strategies aimed at diminishing the long-term prognosis of children with comorbidities.

Dr. Thomas Spencer, associate chief of the clinical and research program in pediatric psychopharmacology at Massachusetts General Hospital, presented data indicating that adults and children with ADHD have similar psychiatric comorbidities.

He focused on another study by Biederman et al. that evaluated a clinically referred sample of 219 adults with ADHD. They were compared with 215 age- and sex-matched controls who were participating in other studies at the hospital. Dr. Spencer noted that most patients with ADHD had not received any form of treatment, reflecting that the condition is not yet well recognized in adults.

Results showed that among these adults, ADHD was associated with high rates of antisocial, mood, anxiety, and substance use disorders.

"Most of the comorbidity starts quite early," Dr. Spencer said. "ADHD seems to be at least a marker, if not a[n] etiologic factor, for the early onset of these comorbid disorders, for anxiety, depression, and bipolar disorder."

Adults with ADHD showed especially high rates of past severe major depression and alcohol dependence; Dr. Spencer said it is therefore important to ascertain a lifetime psychiatric history to determine prognosis and appropriate treatment.

He also provided general principles for pharmacotherapy, advising that clinicians treat the worst disorder first, which tends not to be ADHD. Additional treatment may be necessary to improve ADHD symptoms.

Finally, Ronald Kessler, a professor of health care policy at Harvard Medical School, reviewed findings from the National Comorbidity Survey Replication. In the most recent wave, 3,199 respondents aged 18 to 44 years were assessed for ADHD.

ADHD was prevalent in 4.4% of the adults and appeared unrelated to age. However, rates were higher in men (relative to women), in people who had been previously married (relative to currently married people), who had a lower education, or who were unemployed.

The odds of comorbid mood, anxiety, substance use, or impulse disorders in the 12 months prior to the study were significantly increased in the adults who had ADHD (>=2.8-fold; P=.05).

The data also revealed a consistent pattern of temporal priorities, so that among patients with mood, substance, impulse, or any anxiety disorder (except specific phobia), ADHD onset was usually first and subsequently followed by the comorbid condition(s).

Also, persistent--rather than remitted--ADHD was associated with significantly higher rates of bipolar disorder, several types of anxiety disorders, and any impulse disorder.

"So, it seems like the main thing that's driving the association between ADHD and the comorbid conditions in adulthood is the intertemporal lagged association between early ADHD and risk of the subsequent first onset of a disorder for reasons that in some cases, clearly, are not causal, and in other cases, could be," Kessler summarized.

By Shayna Muckerheide

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