A study published in the journal Brain shows that the pleasure responses to risk taking in the reward centers of the brain are stronger in people with bipolar disorder. The study was conducted by a team of cognitive neuroscientists from the University of Manchester and the University of Liverpool in the United Kingdom.
A group of subjects with bipolar disorder and a control group of subjects underwent a series of fMRI scans while playing roulette. Risk-and-reward activities like gambling are known to stimulate the nucleus accumbens, informally known as the brain’s “reward center.” The researchers wanted to determine whether there was any significant difference between the two groups in the way this reward center responded to stimulus.
Parameters of the Study
The U.K. study involved one group of 20 people with bipolar disorder who were not experiencing current episodes of depression or mania, as well as a group of 20 people with no known illnesses. All participants were between the ages of 18 and 45 and had no current substance use problems.
Patients were asked to make bets on a roulette game in order to evaluate their response to short-term rewards, long-term rewards, high-risk situations and low-risk situations. They could make either “safe” bets with a high (75 percent) probability of success, or risky bets with a low (25 percent) probability of success. In addition, they were directed to place bets of either three or nine British pounds. The participants were able to keep any money that they won, so that their responses to risks and rewards were genuine.
Reward Center Focuses on Short-Term Goals
The brain’s reward center encourages people to seek short-term success and pleasure, because these are the experiences that cause this part of the brain to be active. However, this relatively primitive part of the brain works in combination with other, more highly-developed, areas of the brain that help us to recognize the benefits of striving toward long-term goals.
This new study demonstrated that the prefrontal cortexes in participants with bipolar disorder were less able to control the impulsive behavior encouraged by their active reward centers. The participants without a bipolar diagnosis were able to make better choices when it came to maximizing the long-term results of their roulette game, while the prefrontal cortex in the subjects with bipolar disorder was less active. Overall, the bipolar subjects demonstrated stronger positive responses to winning money, but were less likely to be influenced by probability when placing their bets.
Benefits and Challenges of Risk-Taking
Professor Wael El-Deredy of the University of Manchester believes there may be some advantage to having a very active nucleus accumbens. He says that a positive response to high risk and high reward situations may explain why many people with bipolar disorder are typically very successful. He believes that the exceptionally strong response to positive experiences may drive people to continue pursuing their goals.
However, Professor El-Deredy and the other authors of the new study also note that this strong reward response can also get people into serious trouble. Without interference from the prefrontal cortex helping people to channel high levels of excitement and motivation into long-term goals, such strong reward feedback can lead people to pursue immediate pleasure at the cost of long-term comfort and stability.
The impact of this brain behavior in patients with bipolar disorder is easy to recognize. People with bipolar diagnoses engage in impulsive and risky behavior when they are experiencing manic episodes. They may do things such as max out credit cards on shopping sprees, gamble nonstop or make elaborate plans that are unlikely to ever become a reality.
Symptoms such as these in bipolar patients have been recognized for years, but the U.K. study helps science to better understand exactly what occurs in patients’ brains when they exhibit this kind of behavior.
The researchers believe that understanding the brain mechanisms involved in chronic mental illnesses like bipolar disorder is the key to creating more effective treatments in the form of therapy or medication.