Development of bipolar disorder and other comorbidity among youth with attention-deficit/hyperactivity disorder

To examine development of bipolar spectrum disorders (BPSD) and other disorders in prospectively followed children with attention-deficit/hyperactivity disorder (ADHD).

In the Longitudinal Assessment of Manic Symptoms (LAMS) study, 531 of 685 children age 6-12 (most selected for scores > 12 on General Behavior Inventory 10-item Mania scale) had ADHD, 112 with BPSD, and 419 without. With annual assessments for 8 years, retention averaged 6.2 years. Chi-square analyses compared rate of new BPSD and other comorbidity between those with versus without baseline ADHD and between retained versus resolved ADHD diagnosis. Cox regression tested factors influencing speed of BPSD onset.

Of 419 with baseline ADHD but not BPSD, 52 (12.4%) developed BPSD, compared with 16 of 110 (14.5%) without either baseline diagnosis. Those who developed BPSD had more nonmood comorbidity over the follow-up than those who did not develop BPSD (p = .0001). Of 170 who still had ADHD at eight-year follow-up (and not baseline BPSD), 26 (15.3%) had developed BPSD, compared with 16 of 186 (8.6%) who had ADHD without BPSD at baseline but lost the ADHD diagnosis (χ²  = 3.82, p = .051). There was no statistical difference in whether ADHD persisted or not across new BPSD subtypes (χ²  = 1.62, p = .446). Of those who developed BPSD, speed of onset was not significantly related to baseline ADHD (p = .566), baseline anxiety (p = .121), baseline depression (p = .185), baseline disruptive behavior disorder (p = .184), age (B = -.11 p = .092), maternal mania (p = .389), or paternal mania (B = .73, p = .056). Those who started with both diagnoses had more severe symptoms/impairment than those with later developed BPSD and reported having ADHD first.

In a cohort selected for symptoms of mania at age 6-12, baseline ADHD was not a significant prospective risk factor for developing BPSD. However, persistence of ADHD may marginally mediate risk of BPSD, and early comorbidity of both diagnoses increases severity/impairment.