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Having Relatively Few Dopamine Receptors May Cause ObesityAired February 2, 2001 - 4:40 p.m. ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
JOIE CHEN, CNN ANCHOR: There's scientific evidence that being overweight may be more than just a matter of willpower. New research shows a chemical in the brain may play a significant role.
CNN's medical correspondent Elizabeth Cohen joins us now with more on the dopamine connection.
Elizabeth, I hope you're going to make us all feel better about...
ELIZABETH COHEN, CNN MEDICAL CORRESPONDENT: That's right, absolutely.
Well, the dopamine connection makes it sound like a movie, but dopamine is actually a neurotransmitter, that is, a chemical in the brain, that's responsible for feelings of pleasure, for feeling full, for feeling satisfied.
But you can have all the dopamine you want and it won't work if you don't have receptors in the brain to pick it up. And what they found in the study that was just published in the medical journal the "Lancet" out of London is that obese people did not have as many receptors as non-obese people.
And what they did is they did PET scans on both obese and non- obese people. And as you can see here, the non-obese subjects had a lot of receptors, as represented by red in this PET scan -- there's a lot of red in there. However, take a look at the obese subject: not as much red; hardly any at all. And that's a very clear difference between folks who are obese and folks who are not. Something also that's very interesting, is that folks were-- there was even less red if you were heavier. So, in other words, the heavier you were, the fewer receptors you had for dopamine.
So the scientists' theory is that people overeat because they're not feeling that kind of pleasure and that satisfaction, so they just keep eating, sort of like addicts just keep taking drugs in order to feel pleasure.
And PET scans of addicts, interestingly enough, also show that they don't have enough receptors.
CHEN: So Elizabeth, how is all of this supposed to help me lose weight? COHEN: Well, you are not obese, so I don't want to help you lose weight.
CHEN: Well, from the waist down -- anyway, how is it going to help me; that's all I really want to know; you can do all the dopamine you want...
COHEN: Right -- dopamine, PET scans, yes fascinating.
However, the way that it will hopefully help people lose weight is that -- if they figure out that this finding is really, truly -- there's a chicken-egg problem here; in other words, they don't know if obese people are born with not enough neurotransmitters -- not enough receptors for dopamine or, perhaps, because they're obese they don't have enough neurotransmitters; it's hard to -- enough receptors.
It's hard to know which comes first. Once they figure that out, perhaps they can design drugs that would increase the number of receptors. In the meantime, exercise has been found, in some studies, to increase the number of receptors; maybe not as efficiently as a drug might in the future, but it might possibly work.
So I know it's not very exciting, but exercise might make you feel better, feel more pleasure. Not you, but...
CHEN: Can't you come up with something better than exercise?
COHEN: I'm sorry; no, nothing. At this point, nothing.
CHEN: Eat less, exercise more; right. Elizabeth Cohen back with us from her medical unit.
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