Body clock changes can predict bipolar relapse

Underneath the normal disorder of everyday lives there is a steady, strong and immutable beat that never changes. It is the pulse to which every living thing on the planet sets its rhythm of life, and it has been there since the very creation of our planet – the rising and setting of the sun.

The biological clocks of humans, animals and even plants are intricately linked with day and night. But occasionally our body clocks fall out of sync, and research shows this can have potentially serious psychological consequences.

Swinburne University of Technology researcher Dr Greg Murray has keenly studied the body clock or, in technical terms, the circadian system, and found its rhythms can have profound effects on human mood.

His research has shown a definite connection between the body clock and certain psychological responses, including the capacity to trigger relapses in patients with bipolar disorder.

Mood disorders such as bipolar disorder have long been linked with sleep problems, suggesting that the circadian system plays a role in these conditions. “If you take seriously this idea that the body clock is part of a causal pathway to mood disorders, then a natural deduction is that monitoring clock function might provide early warning of relapse in vulnerable people,” Murray said.

Murray and his PhD student Ben Bullock have just finished putting this theory to the test in a project funded by beyondblue, the National Depression Initiative. Twelve volunteers with bipolar disorder were fitted with wrist-worn devices designed to monitor their circadian system by measuring their physical activity throughout the day and night. According to Murray, these actigraphs give a useable measure of circadian output under natural conditions.

The study subjects were tracked for up to 12 months. In that time, one participant experienced a serious relapse that landed him in hospital. “For our purpose, it was very interesting that circadian activity data really did show a marked signal of deterioration in the days and even weeks before the relapse.” Instead of his activity patterns operating on a 24-hour cycle, the participant shifted to a 48-hour cycle of wakefulness and broken, disturbed rest.

“With Dr Indic Premananda, from the University of Massachusetts, we are analysing the actigraph data to find the time scale at which rhythm disruption is most apparent.”

In the next stage of research, the team wants to see if signals of rhythm disruption in patients can be used as markers of vulnerability to bipolar disorder in the general population.

(Source: Swinburne University : September 2008)