Researchers pinpoint overeating in dementia brain

Researchers have discovered why some people with dementia are compelled to massively overeat, opening the way for better diagnosis and the development of new treatments for the disease.

The research, led by Dr Olivier Piguet from Neuroscience Research Australia, shows for the first time that some people with frontotemporal dementia have deterioration in the brain region that controls hunger.

“We think the cells in this brain region lose the ability to tell these individuals when they’ve had enough to eat,” says Dr Piguet.

These people become unable to control their urge to eat, gorging on sweet and carbohydrate-rich foods and eating in socially inappropriate ways, a situation which is unhealthy for the individual and highly distressing for the family.

“They may steal food from people’s plates or go looking for a bowl of sugar and eat the whole thing,” says Dr Piguet.

“Some people will even eat inedible objects, like a pen. Because we now know the exact site of this problem, we can work on understanding the mechanism and designing a treatment to target this symptom,” he says.

Frontotemporal dementia (FTD) is a type of dementia that can affect people in their 50s and 60s, and as young as 30 years of age. There are currently no treatments for FTD.

The Neuroscience Research Australia study was published in Annals of Neurology.

In an unrelated American breakthrough, with the help of volunteers aged 18 to 89, University of California Irvine (UCI) researchers have identified for the first time in humans a long-hidden part of the brain called the perforant path.

Scientists have struggled for decades to locate the tiny passage, which is believed to deteriorate gradually as part of normal ageing and far more quickly due to Alzheimer’s disease.

The UCI researchers developed and used a new ultrahigh-resolution technique – outlined in a paper published in the Proceedings of the National Academy of Sciences – to electronically peer through dense matter near the brain’s hippocampus in search of the perforant path.

The passageway is basically a bundle of nerve fibers, lined up like straws, connecting a region called the entorhinal cortex to the seahorse-shaped hippocampus.

By monitoring the brains of Burns and others via their ultrahigh-resolution technique – know as diffusion tensor imaging – the UCI team was able to detect water molecules moving in the exact area where they knew the passage had to be. The scientists then painstakingly tracked the progress of the molecules along the length of the fiber bundle, thereby identifying the perforant path.

“There was definitely an ‘aha’ moment when we knew we had finally found it,” said Mike Yassa, postdoctoral researcher and lead author of the paper.

They were also able to measure the strength of the passageway, confirming that in normal brains it weakens gradually with age, reducing the capacity to quickly recall details but not wiping out memory.