Bipolar disorder and ADHD do not share transgenerational link
MedWire News: Results from a US study do not support a significant transgenerational familial association between attention-deficit hyperactivity disorder (ADHD) and bipolar spectrum disorder (BSD).
Writing in the Journal of Affective Disorders, L Eugene Arnold (Ohio State University, Columbus) and colleagues observe: "Both BSD (including bipolar I disorder, bipolar II disorder, cyclothymic disorders, and bipolar disorder not otherwise specified) and ADHD manifest symptoms of impulsivity, hyperactivity, and irritability, with impairments in social relations, increased substance use, and underachievement."
Furthermore, they say that previous studies have shown high rates of ADHD in BSD patients, and vice versa.
To investigate whether these disorders share a transgenerational familial association, the team studied the parents of 707 children who participated in the Longitudinal Assessment of Manic Symptoms study.
Of these children, who were aged between 6 and 12 years, 421 had ADHD without BSD, 45 had BSD without ADHD, 117 had ADHD and BSD, and 124 had neither disorder.
All of the children's parents were assessed for ADHD symptoms and BSD mania symptoms using structured questionnaires.
The researchers found that the prevalence of mania symptoms in the parents of children with ADHD plus BSD and BSD alone was similar and significantly higher than in those of children with ADHD alone or neither disorder, at 32% and 49% versus 17% and 14%, respectively.
Furthermore, the prevalence of ADHD symptoms in the parents of children with BSD alone was significantly lower than that in the parents of children with ADHD alone, ADHD plus BSD, or neither disorder, at 15% versus 32%, 32%, and 24%, respectively.
The researchers note that a family history of manic symptoms, but not ADHD symptoms, was significantly associated with parent-rated severity of mania symptoms in children.
Arnold and team summarize: "This carefully characterized sample of children from mental health clinics shows significant associations between parent and child psychopathology within diagnostic category, but not the suspected 'crossing over' of ADHD and manic symptoms transgenerationally."
They conclude: "These results do not support familial linkage of BSD and ADHD; they are compatible with heritability of each disorder separately with coincidental overlap."
By Mark Cowen