[Everyday stress, routines and bipolar spectrum]

Bipolar patients relapse more frequently under conditions of stress, even when compliant with prescribed medication. Although the biological bases of stress reactivity remain widely debated, the disruption of biological or circadian rhythms has been suggested as one possible mechanism through which stress increases the risk of episodes. This hypothesis has gained support from recent evidence demonstrating that the disruption of social rhythms is particularly implicated in the onset of manic episodes. However, it is currently unknown to what extent bipolar patients may differ from normal controls in terms of the basic prevalence and nature of daily life routines, or if such individuals are more sensitive to the disruption of such rhythms following exposure to stress.

Using a dimensional perspective of bipolar disorder, 1728 French university students were first screened concerning diverse psychological and clinical characteristics. Two hundred and twelve individuals at high or low-risk for mood and substance use disorders were then invited to participate in a week-long period of ambulatory monitoring using the experience sampling method (ESM). During this phase, participants were given a preprogrammed PDA microcomputer which provided ambulatory assessments of behaviour and stress at fixed intervals (randomized across participants). At the end of the ESM phase, the microcomputers were collected and structured diagnostic interviews were administered to each participant. For the purposes of the current study, analyses focused on a subsample of 92 individuals, reflecting the 28 participants who met lifetime criteria for a manic (n=15) or hypomanic episode (n=13), and the 64 individuals who were free of any lifetime disorder. Data were analyzed using hierarchical nonlinear (Bernoulli) models for repeated measures. Covariates included age, sex, frequency of substance use and cognitive vulnerabilities assessed at screening. A Bonferroni correction was applied to adjust alpha levels within each category of activity, social interaction or environmental context.

A total of 2777 valid ESM assessments were provided by the final sample concerning their behaviour and activities across diverse daily life contexts. Individuals having a lifetime history of mania or hypomania were significantly less likely than normal controls to have daily life routines relative to being at work, in class, having social contact with work colleagues or students, and to be performing personal hygiene activities. However, such individuals were more likely to be in the company of a romantic partner at the same moment each day. Time-lagged analyses demonstrated that, following conditions perceived as stressful, individuals with a history of mania or hypomania were less likely to repeat the same activities or behaviour of previous days concerning being at parents' or family's house, being at friends, and travelling or commuting, but more likely to be in a work environment, and in a bar or restaurant.

The findings provide support for the notion of differences in daily life rhythms and routines among individuals with bipolar spectrum conditions, as well as the possibility of increased stress vulnerability in this population. Although a conservative analytic strategy was employed to minimize chance associations, the present findings can be considered only as preliminary and should be interpreted with caution in light of the moderate sample size, young age and non treatment-seeking nature of the sample. Future controlled investigations using ambulatory monitoring techniques are needed to pursue the investigation of these questions in treated samples.