Risk factors for sleep apnea in children with bipolar disorder

Background: While studies have suggested an increased prevalence of Obstructive Sleep Apnea (OSA) in adults with Bipolar Disorder (BPD), little is published about children with BPD. Behavioral difficulties including emotional liability, depression and poor school performance are commonly reported in children with either BPD or OSA. Comorbid medical disorders may exacerbate the course of BPD. We reviewed demographic and polysomnogram characteristics of children with BPD to help outpatient identification of OSA.

Methods: A single center retrospective chart review of children with BPD referred for a polysomnogram (PSG) over a ten-year period was conducted. There were 27 children identified whose diagnosis of BPD was independently verified by a child psychiatrist using DSM-IV standard criteria.

Results: Six (22%) children had OSA with a median apnea-hyponea index of 7.5 events per hour. Variables that were significantly different between the OSA and non-OSA groups were: median BMI (47 vs 30 kg/m(2), p=0.001); sleep efficiency (78.2% vs 91%, p=0.009); and oxygen saturation nadir (82% vs 92%, p=0.0003). There was no difference found in snoring percentage on PSG between the two groups.

Limitations: The retrospective design from a single tertiary center limited the cohort size. Only secondary verification of the diagnosis of BPD from the available medical record was possible.

Conclusions: Our findings suggest that extreme obesity (BMI >40 kg/m(2)), oxygen desaturation during sleep and frequent nocturnal awakenings are associated with OSA in children with BPD. Traditional clinical parameters for obesity and snoring, per se, are poor predictors of OSA in children with BPD.