title: The association between insomnia-related sleep disruptions and cognitive dysfunction during the inter-episode phase of bipolar disorder.
abstract: Sleep disturbance and cognitive dysfunction are two domains of impairment during inter-episode bipolar disorder. Despite evidence demonstrating the importance of sleep for cognition in healthy and sleep-disordered samples, this link has been minimally examined in bipolar disorder. The present study tested the association between insomnia-related sleep disruptions and cognitive dysfunction during inter-episode bipolar disorder. Forty-seven participants with bipolar disorder and a comorbid insomnia diagnosis (BD-Insomnia) and 19 participants with bipolar disorder without sleep disturbance in the last six months (BD-Control) participated in the study. Two domains of cognition were assessed: working memory and verbal learning. Insomnia-related sleep disruptions were assessed both categorically (i.e., insomnia diagnosis) and dimensionally (i.e., total wake time, total sleep time, total wake time variability, and total sleep time variability). Hierarchical linear regressions, adjusting for participant age, demonstrated that insomnia diagnosis did not have an independent or interactive effect on cognition. However, regardless of insomnia diagnosis, greater total sleep time variability predicted poorer working memory and verbal learning performance. Further, following sleep treatment, a reduction in total wake time predicted improved working memory performance and a reduction in total sleep time variability predicted improved verbal learning performance. These findings raise the possibility that sleep disturbance may contribute to cognitive dysfunction in bipolar disorder and highlight the importance of treating sleep disturbance in bipolar disorder.
authors.affiliation: Department of Psychology, University of California, Berkeley, 3321 Tolman Hall, 94720 Berkeley, CA, USA.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Kanady
authors.affiliation: Department of Psychiatry, University of Pittsburgh School of Medicine, 3811 Ohara St, 15213 Pittsburgh, PA, USA.
authors.forename: Adriane M
authors.initials: AM
authors.lastname: Soehner
authors.affiliation: VA Boston Healthcare System, 150 S. Huntington Ave. Boston, 02130 MA, USA.
authors.forename: Alexandra B
authors.initials: AB
authors.lastname: Klein
authors.affiliation: Department of Psychology, University of California, Berkeley, 3321 Tolman Hall, 94720 Berkeley, CA, USA. Electronic address: aharvey@berkeley.edu.
authors.forename: Allison G
authors.initials: AG
authors.lastname: Harvey
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000150:complications*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012044:Regression Analysis; D007319:Sleep Initiation and Maintenance Disorders / Q000209:etiology*; D014706:Verbal Learning; D055815:Young Adult
keywords: Bipolar disorder; Cognition; Insomnia; Inter-episode phase; Verbal learning; Working memory