Day-to-day variability in bipolar disorders
Background. Bipolar disorder is characterised by recurrent acute episodes of mania and depression with the common occurrence of subsyndromal symptoms between episodes. Episode recurrence and frequent inter-episode symptoms have made identification of the factors that influence relapse an important focus for research in bipolar disorder. Objective. To determine whether dysregulation in bipolar disorder would be exhibited, outwith acute mania, in day-to-day variability and whether variability was associated with risk of relapse. Design. A prospective daily monitoring study was conducted with bipolar disorder and general population samples. Twenty participants with a bipolar episode experienced in the previous two years were recruited from a Lithium Clinic. A control group often participants from the general population were recruited by opportunity sampling. Main outcome measures. Biological, behaviour, cognition, and affect measures included self-report measures of behavioural activation/inhibition, social rhythms, self esteem, positive affect, negative affect, elation, depression and objective actigraph estimation of the sleep-wake cycle and circadian rhythms. Results. Lower self esteem, lower positive affect, higher negative affect, higher depression levels and greater variability in self esteem, night waking and sleep efficiency across 14 days were evident in bipolar disorder. Survival analyses suggested greater variability in self esteem and sleep efficiency predicted earlier admission in bipolar disorder. Conclusions. Greater day-to-day variability in bipolar disorder was observed compared to the general population. Underlying disturbances in biological, cognition and affect measures were evident in bipolar disorder. Findings were clinically important since sleep and self esteem disturbances may be considered as potentially modifiable in reducing risk of relapse in bipolar disorder.