Risk for switch from unipolar to bipolar disorder in youth with ADHD: A long term prospective controlled study

Abstract 

Background

To investigate whether ADHD is a risk factor for switches from unipolar to bipolar disorder over time.

Methods

Data from two large controlled longitudinal family studies of boys and girls with and without ADHD and their siblings were used. Subjects (n=168) were followed prospectively and blindly over an average follow-up period of 7 years. Comparisons were made between youth with unipolar major depression who did and did not switch to full or subthreshold BP-I disorder at the follow-up assessment. Subjects were assessed at baseline and follow-up on multiple domains of functioning. Positive family history of parental psychiatric disorders was also compared between groups.

Results

ADHD was associated with a significantly higher risk for switches from unipolar to bipolar disorder (28% versus 6%; z=2.80, p=0.005). In subjects with ADHD, switches from unipolar to bipolar disorder were predicted by baseline comorbid conduct disorder, school behavior problems, and a positive family history of parental mood disorder.

Limitations

Psychosis was an exclusionary criterion in the original ascertainment of the studies of ADHD probands, so we were unable to test this as a predictor of switching to BPD.

Conclusions

ADHD is a risk factor for switches from unipolar to bipolar disorder, and switches could be predicted by the presence of baseline conduct disorder, school behavior problems, and a positive family history of a mood disorder in a parent. These characteristics can aid clinicians in their treatment of youth with MDD.

Keywords: Pediatric bipolar disorder, ADHD, Risk factors, Switch