Alzheimer’s disease – Appetite might be linked to risk of Alzheimer’s
The hormone leptin controls your appetite
Leptin is a potent and important appetite-regulating hormone – if you’ve just polished off a couple plates of food at a buffet, your blood leptin levels will rise and signal to your brain that you’re full.
The picture to the right shows an obese mouse that is missing the leptin gene and thus doesn’t produce leptin in its body. When it starts eating, it doesn’t stop and becomes obese.
The same thing happens in a small population of humans who are missing the leptin gene. They can’t control their appetite and get fat. But as always in biology, the story is more complicated. Some obese people have exactly the opposite effect – higher leptin levels than normal.
This might be because they have a genetic defect that makes them resistant to the effects of the hormone – when their bodies detect that the existing leptin in the bloodstream isn’t working, more leptin is pumped out, leading to higher levels.
Higher leptin = less risk of Alzheimer’s disease
A group of researchers based in Boston University have just finished an epic 12-year study of over 750 elderly people, where they tracked leptin levels and brain function (with brain scans). In short, they found that people with overall higher leptin levels at the start of the study ended up with less Alzheimer’s disease and healthier brains.
This is exciting because it would be extremely powerful to find a way to predict whether somebody is going to get Alzheimer’s disease later in their life, allowing early intervention and treatment – this study shows that leptin might be a useful predictive biomarker.