Reward system ‘broken’ for those with bipolar disorder

Depression and mania are linked to abnormalities in the bio-behavioural system that manages the pursuit of reward in humans, the sixth annual Barbara Dicker Oration has heard.

Delivering the oration, Professor Sheri Johnson from the University of California told a packed lecture that the reward system in people with severe depression and bipolar disorder was “broken”.

Professor Johnson, a world-renowned expert on bipolar disorder, says almost 20% of the population will suffer from some sort of mood disorder in their lifetime.

“It is a leading top ten cause of medical disability worldwide and mood disorders carry with them an incredibly heightened risk of suicide,” she says.

Professor Johnson says that there is a direct correlation between bipolar disorder and the reward system in the brain known as the nucleus accumbens.

Studies on the nucleus accumbens of people with bipolar show they have a high propensity to take risks in pursuit of a reward, she says. 

“People talk about the nucleus accumbens as a system that involves willingness to expend energy and effort to obtain a reward,” she explains.

“The nucleus accumbens also lights up in humans if making a decision to work harder for a reward.”

She says people who suffer from bipolar 1 disorder are “hyper reward sensitive” and are prepared to work harder and take more risks to achieve the reward.

“Ambition is elevated in bipolar 1 disorder during well periods and after multiple hospitalisations,” she explains.

Professor Johnson says knowing there is a link between the brain’s rewards system and bipolar disorder is helping researchers predict the onset of bipolar disorder and the depth and the length of a manic episode.

She says research has found that significant life events or obtaining life goals can trigger episodes of mania.

She says this indicates that the nucleus accumbens of a person with bipolar disorder is destabilised during key times.

“So, just at the moment when things are going beautifully well for a lot of these folks, the reward system can’t quieten back down,” she says.

Professor Johnson says people who suffer from bipolar disorder are more likely to be creative.

“People with bipolar disorder and their family members are more likely to become successfully employed artists and also more likely to have highly creative scientific careers than the general population.”

Professor Johnson was also part of Swinburne’s ground-breaking research which looked into the brain’s reward system throughout the day.

The study found the reward centre acts differently across the day, peaking in the morning and in the evening

Swinburne has invested $40 million to establish one of Australia’s newest and most complete human brain imaging research facilities located in the Advanced Technologies Centre.

This centre incorporates state-of-the-art facilities including a Magnetic Resonance Imaging (MRI) machine and Victoria’s first Magnetoencephalography (MEG) machine. The combination of these machines make this facility unique in the southern hemisphere.

The Barbara Dicker Brain Sciences Foundation was established by Mr Ian Dicker AM and his family in 2012 in honour of his late wife, Barbara Dicker. The foundation aims to contribute to the wellbeing of individuals and communities by supporting research in the areas of dementia, depression and sleep disorders.

(Source: Swinburne University of Technology)