Circadian rest–activity rhythm in individuals at risk for psychosis and bipolar disorder

Abstract

BackgroundAt-risk mental states (ARMS) are clinical syndromes that are associated with higher risk, compared with the general population, for developing psychosis and bipolar disorder. Circadian rhythm misalignments have been proposed to be part of this early phase of the clinical course. ObjectiveTo compare circadian rhythm of activity and rest changes between ARMS individuals and a healthy control group. MethodsForty volunteers of both genders, aged between 13 and 27years old, participated in this study (n=20 ARMS group, and n=20 healthy controls). The ARMS individuals were classified as ultra-high risk for psychosis according to the CAARMS (Comprehensive Assessment of At-risk Mental State) or at high risk for bipolar disorder according to criteria proposed by Bechdolf and colleagues. Participants used an actigraph for fifteen days, kept a sleep diary, and completed the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, and a Morningness–Eveningness Questionnaire. ResultsCompared with healthy volunteers, the ARMS group presented worse sleep quality (P=0.010); longer nap durations (P=0.038), shorter wake times (P=0.001), higher total sleep times (P=0.011), and shorter activity duration (P=0.021), sleep rhythms were more fragmented, the circadian rest–activity rhythms were less synchronized with the dark–light cycle and had lower amplitudes of motor activity. ConclusionThe results suggest alterations in the circadian rest–activity rhythms (and likely in sleep–wake cycle patterns) in ARMS individuals compared with healthy controls. It is possible that circadian rhythms of activity and rest changes are one of the prodromal clinical and behavioral expressions of the brain changes that underlie ARMS individuals.