New insight into links between obesity and activity in the brain

October 26, 2010

Scientists have revealed that an anti-obesity drug changes the way the brain responds to appetising, high-calorie foods in obese individuals. This insight may aid the development of new anti-obesity drugs which reduce the activity in the regions of the brain stimulated by the sight of tasty foods.

Researchers at the University of Cambridge discovered that the anti-obesity drug sibutramine reduced in two regions of the brain, the and the , both of which are known to be important in appetite control and eating behaviour. Their findings are reported today in The .

Professor Paul Fletcher, from the Department of Psychiatry and the Behavioural & Clinical Neuroscience Institute at the University of Cambridge and one of the paper's authors, said: "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."

Using functional magnetic resonance imaging (fMRI), the researchers measured brain activity while obese volunteers viewed pictures of appetising high-calorie foods – like chocolate cake – or pictures of low-calorie foods – like broccoli. The brain scanning was carried out both after two weeks of treatment with the anti-obesity drug, sibutramine, and two weeks of placebo treatment.

On placebo, it was shown that simply seeing pictures of appetising foods caused greater activation of many regions of the brain that are known to be important for reward processing. On sibutramine, however, they found that the anti-obesity drug reduced brain responses to the appetising foods in two regions of the volunteers' brain - the hypothalamus and the amygdala. These two regions are known to be important in appetite control and eating behaviour. Additionally, people who had the greatest reduction of brain activation following drug treatment tended to eat less and to lose more weight.

Professor Ed Bullmore, from the Department of at the University of Cambridge and director of the GlaxoSmithKline (GSK) Clinical Unit in Cambridge (CUC), said: "Our results help us to understand more precisely how anti-obesity drugs work in the brain to change eating behaviour and hence, ultimately, to assist people in losing weight.

"The most exciting aspect of these results is that they help us to see that brain and behaviour 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 behaviour is regulated by reward and satiety processing circuits in the ."

More information: The paper 'Distinct modulatory effects of satiety and sibutramine on brain responses to food images in humans: a double dissociation across hypothalamus, amygdala and ventral striatum' will be published on 26 October 2010 in The Journal of Neuroscience.

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8 comments

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CarolinaScotsman
5 / 5 (1) Oct 26, 2010
Sibutramine has been withdrawn from the market in both the UK and the US as being unsafe after being implicated in heart related deaths. Was this study done before or after the drug was recalled? If after, why put the study participants at risk and bother to report it?
PieRSquare
5 / 5 (1) Oct 26, 2010
Sibutramine has been withdrawn from the market in both the UK and the US as being unsafe after being implicated in heart related deaths. Was this study done before or after the drug was recalled? If after, why put the study participants at risk and bother to report it?
It was withdrawn in the US less than three weeks ago so the study would have been over before that happened. More info: http://en.wikiped...utramine
Even if this particular drug isn't worth the risks the research is still useful to get a better understanding of the mechanisms behind obesity and may lead to more effective drugs with fewer side-effects.
RobertKarlStonjek
not rated yet Oct 27, 2010
Botox injections into the jaw muscles should do the job...
LivaN
not rated yet Oct 27, 2010
the research is still useful to get a better understanding of the mechanisms behind obesity and may lead to more effective drugs with fewer side-effects.


The mechanisms behind obesity, in this case, are LACK OF WILLPOWER.
Rather than make the decision to not eat that yummy looking deep-fried chocolate bar, it's easier to alter one's brain chemistry so we no longer want it. My dog also shovels food down his gullet with little regard. Luckily he can't open his food bin, or I'd have to find a country where sibutramine isn’t banned.

I'm not saying the knowledge this study provides is useless, far from it. I do however think the motivation behind it is pitiful.
genastropsychicallst
1 / 5 (2) Oct 27, 2010
... for example. Is a ship build for obesity floating ore against activity sinking ? Both no, it's made for traveling. Can we blinking lightspeed ? No, we can also not linking it. New ? To be be read at my website ! ...
thingumbobesquire
1 / 5 (1) Oct 27, 2010
I guess this research gives a whole new meaning to the term "fat head."
Skeptic_Heretic
not rated yet Oct 27, 2010
Sibutramine has been withdrawn from the market in both the UK and the US as being unsafe after being implicated in heart related deaths. Was this study done before or after the drug was recalled? If after, why put the study participants at risk and bother to report it?
Article published Oct 26th 2010 Journal of Neuroscience.
PieRSquare
not rated yet Oct 27, 2010
The mechanisms behind obesity, in this case, are LACK OF WILLPOWER.
While making glib moral judgments might be emotionally satisfying it won't help anyone.
We live a lifestyle that our bodies aren't adapted to do well in, urban environments are particularly bad. High stress, easy to find junk food/hard to find nutritious food, sedentary lifestyles, lack of nutritional education, etc... All these factors make it more difficult to maintain good health.
As individuals it is important to educate ourselves and develop self-control but there are systemic problems which seem to be the major driver. These problems wont go away anytime soon, so if there's a medication for those who have been struggling and have failed for whatever reason can help, then why not?
If it works for these individuals they will be better off and the costs to society will be reduced. Not ideal, but when the deck is stacked against you, take what you can get.

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