Subscribe now

A gene variant that helps us gain weight may shrink our brains into the bargain.

Elderly obese people are more likely to develop dementia and their brains tend to be smaller than those of people of normal weight. This has been put down to clogged arteries slowing the blood flow to the brain, killing neurons.

But now Paul Thompson’s team at the University of California, Los Angeles, has found that a gene variant linked to obesity may harm the brain directly.

Half of Europeans and West Africans have a variant of a gene called FTO that increases the risk of obesity by two-thirds. The variant is thought to affect metabolism and fat storage.

Problem-solving

When Thompson’s team looked at brain scans of 206 healthy people aged 70 to 80, they found that those with at least one copy of the FTO variant had 8 per cent less volume in their frontal lobes and 12 per cent less in the occipital lobes, compared with their counterparts lacking the variant. The brains of those with the variant “looked 16 years older”, Thompson reckons.

The study’s participants did not have cognitive problems. However, these brain areas are critical to problem-solving and perception, and brain atrophy there increases the risk of dementia and memory problems, Thompson says.

The FTO variant could be damaging the brain indirectly by helping to make people fatter, but Thompson reckons it plays a more direct role, too, as FTO is expressed at high levels in the brain.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0910878107

Topics:

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

Sign up