Young people with major depression have an increased risk of conversion to bipolar disorder if they have comorbid attention deficit/hyperactivity disorder (ADHD), suggest findings from a longitudinal follow-up study.
The results showed that 1193 individuals with major depression and comorbid ADHD were 1.5 times more likely to develop subsequent bipolar disorder than 56,830 individuals with major depression alone.
Bipolar disorder was significantly more common in patients with major depression and ADHD than in those with major depression alone, with incidences of 18.9% versus 11.2%.
And it occurred earlier, at an average age of 22.3 years versus 25.2 years. The increased risk of bipolar disorder conversion associated with comorbid ADHD was independent of age, gender, socioeconomic status and other psychiatric comorbidities.
ADHD was not the only independent risk factor for subsequent bipolar disorder, however, others included disruptive behaviour disorders, substance and alcohol use disorders and anxiety disorders.