How bipolar disorder drives people to riskier gambles

Areas of the brain involved in pursuing and relishing rewarding experiences are more strongly activated in people with bipolar disorder - guiding them towards riskier gambles and away from safer ones, says a study.

The findings may help to design, evaluate and monitor therapies for bipolar disorder.

Patients with bipolar disorder experience episodes of depression and mania (periods of intense excitement and irritability, often leading to very risky behaviour) which occur unpredictably.

"The greater buzz that people with bipolar disorder get from reward is a double-edged sword," said professor Wael El-Deredy from The University of Manchester in Britain.

On the one hand, it helps people strive towards their goals and ambitions which may contribute to the success enjoyed by many people with this diagnosis.

However, it comes at a cost: these same people may be swayed more by immediate rewards when making decisions and less by the long-term consequences of these actions, El-Deredy added.

For the study, researchers invited participants to play a game of roulette in which they made safe or risky gambles. The researchers measured their brain activity throughout using functional magnetic resonance imaging.

Their findings revealed a dominance of the brain's "pleasure centre" which drives us to seek out and pursue rewards, responding to them automatically - before conscious awareness kicks in.

This brain area, called the nucleus accumbens, was more strongly activated in people with bipolar disorder compared to a healthy control group.

Another key difference arose in the pre-frontal cortex, a recently evolved area of the brain which is associated with conscious thought.

The study appeared in the journal Brain.