title: Circadian phase variation in bipolar I disorder.
abstract: Abnormalities in circadian rhythms are prominent features of bipolar I disorder (BD1). To investigate circadian variation in BD1, we evaluated morningness-eveningness (M/E), a stable trait reflecting circadian phase, using the composite scale (CS) among BD1 patients (DSM IV criteria; n = 75), unscreened controls (n = 349), and patients with schizophrenia (SZ) or schizoaffective disorder (SZA) (n = 81). Our analyses showed that CS scores correlated significantly with age but did not differ by gender among the controls. BD1 patients differed significantly from controls and from SZ/SZA patients when age was considered. CS scores were distributed bi-modally among BD1 cases. There are several possible reasons for the observed heterogeneity. Younger BD1 patients, and those with rapid mood swings, were significantly more likely to have lower CS scores (i.e., to score in the 'evening' range and to have later circadian phase). CS scores were also positively correlated with the age at onset and the duration of the most severe depressive episodes. These relationships were not observed among the SZ/SZA groups. Thus, distinct patterns of M/E were noted among BD1 patients and among BD1 subgroups. The impact of medication, mood state, and chronicity on CS scores needs to be considered.
authors.affiliation: Department of Psychiatry and Human Genetics, University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, PA 15213, USA.
authors.forename: Hader A
authors.initials: HA
authors.lastname: Mansour
authors.forename: Joel
authors.initials: J
authors.lastname: Wood
authors.forename: Kodvali V
authors.initials: KV
authors.lastname: Chowdari
authors.forename: Madhulika
authors.initials: M
authors.lastname: Dayal
authors.forename: Michael E
authors.initials: ME
authors.lastname: Thase
authors.forename: David J
authors.initials: DJ
authors.lastname: Kupfer
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Monk
authors.forename: Bernie
authors.initials: B
authors.lastname: Devlin
authors.forename: Vishwajit L
authors.initials: VL
authors.lastname: Nimgaonkar
mesh_terms: D000367:Age Factors; D000818:Animals; D001714:Bipolar Disorder / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D010556:Personality Tests; D011618:Psychotic Disorders / Q000503:physiopathology; D012559:Schizophrenia / Q000503:physiopathology; D013223:Statistics as Topic; D011795:Surveys and Questionnaires