While focusing on the effects of the anti-obesity drug sibutramine, researchers at the University of Cambridge gained new insight into how the brain of an obese person reacts when presented with delicious-looking food.
Through functional magnetic resonance imaging (fMRI), scientists found that an excited response to food in both the hypothalamus and the amygdala — two areas of the brain associated with appetite control and eating habits — was minimized after treatment with sibutramine.
“Currently, there are few drugs that effectively help patients to lose weight. Developing new pharmaceuticals is expensive and risky. However, our findings suggest that we may be able to use brain imaging and psychological tests to make better predictions of which drugs are likely to work,” said Professor Paul Fletcher of the Department of Psychiatry and the Behavioral & Clinical Neuroscience Institute at the University of Cambridge.
After two weeks of treatment with either sibutramine or a placebo, obese participants viewed photos of appetizing foods, such as cake, and also healthy foods, such as vegetables, while researchers measured their brain activity through fMRI scans.
For those on placebo, just viewing photographs of delicious-looking foods caused greater activity in many areas of the brain associated with reward processing.
For participants who took sibutramine, however, researchers found that responses to the appetizing foods were diminished in both the hypothalamus and the amygdala — these regions are known to be important in appetite control and eating behavior. Also, participants with the lowest levels of food-reward stimulation after drug treatment were more likely to eat less and lose more weight.
“Our results help us to understand more precisely how anti-obesity drugs work in the brain to change eating behavior and hence, ultimately, to assist people in losing weight,” said Professor Ed Bullmore of the Department of Psychiatry at the University of Cambridge and director of the GlaxoSmithKline (GSK) Clinical Unit in Cambridge (CUC).
“The most exciting aspect of these results is that they help us to see that brain and behavior are fundamental to understanding and treating obesity. Simply because obesity involves major changes in body weight and body composition, it is easy to imagine that it is entirely ‘a body problem.’ These results remind us that the major cause of obesity in the West is over-eating, and this behavior is regulated by reward and satiety processing circuits in the brain.”
The study can be found in The Journal of Neuroscience.
Source: University of Cambridge