[Editor’s note: This article was revised on 10/28/19 to reflect data showing a signal for persistent attention-deficit/hyperactivity disorder marginally mediating the risk for bipolar spectrum disorder.]

Study data published in the Journal of Child Psychology & Psychiatry suggest that attention-deficit/hyperactivity disorder (ADHD) and bipolar spectrum disorder (BPSD) are largely independently occurring diagnoses, with weak data linking persistent ADHD to later risk for BPSD.

Investigators abstracted data from the Longitudinal Assessment of Manic Symptoms (LAMS) sample, a prospective study of BPSD development in children. The LAMS study recruited participants aged 6 to 12 years from 9 outpatient mental health clinics associated with Case Western Reserve University, the University of Pittsburgh, The Ohio State University, and the University of Cincinnati. Children with a Parent General Behavior Inventory 10-item Mania Scale score exceeding 12 were invited to participate. The LAMS study conducted annual assessments for 8 years, with an average retention of 6.2 years. At each visit, participants were assessed for bipolar disorder symptomatology. Cox regression analysis was used to evaluate the relationship between BPSD and other clinical variables, including ADHD diagnosis at baseline and during follow-up.

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The baseline LAMS sample included 685 children, among whom 67% were boys and 72% were white. The average age was 8.9 (standard deviation, 1.9) years. At baseline, 78% (n=531) of the sample met diagnostic criteria for ADHD, 23% (n=156) met criteria for BPSD, and 16% (n=112) met diagnostic criteria for both. Patients who later developed BPSD had more nonmood comorbidity during the study period than patients without BPSD (P =.001).

In prospective analyses, baseline ADHD was not significantly associated with new onset of BPSD. In addition, ADHD subtype was not predictive of differences in BPSD outcome. However, among patients who still had ADHD at the 8-year follow-up, 15.3% had developed BPSD compared with just 8.6% of those who had lost the ADHD diagnosis over time (P =.051).

Among patients who developed BPSD, speed of onset was not significantly related to baseline ADHD, baseline anxiety, baseline depression, baseline disruptive behavior disorder, maternal mania, or paternal mania. However, patients who had both diagnoses at baseline manifested with more severe symptoms and impairment compared with those who had baseline ADHD and later developed BPSD.

Investigators concluded that ADHD was not a significant prospective risk factor for developing BPSD. They found weak data showing that the persistence of ADHD may slightly mediate the risk for BPSD.

In addition, strong evidence suggests that early-life comorbidity of both disorders may result in greater impairment and symptomatology.

Further study of bipolar disorder in children is necessary to elucidate its pattern of development, particularly in the presence of other psychiatric comorbidities.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Arnold LE, Van Meter AR, Fristad MA, et al. Development of bipolar disorder and other comorbidity among youth with attention-deficit/hyperactivity disorder [published online September 15, 2019]. J Child Psychol Psychiatry. doi:10.1111/jcpp.13122