New evidence to explain why mental function becomes less efficient with ageing

Doctors have found important new evidence to explain why mental function becomes less efficient with ageing.

In the first study of its type in the world, a team at the University of Edinburgh found that worse mental function is linked with abnormally enlarged channels around blood vessels in the brain. The report, published in the Journal of Neurology, Neurosurgery and Psychiatry, will help doctors to better understand the causes of dementia.

Dementia and milder forms of loss of mental ability affects millions of older people every year, but the causes are unclear. Previous research using brain scanning has shown that brain shrinkage and changes in the brain's white matter 'wiring', are associated with mental function slowing down in old age. This research adds a new way in which damage to the brain may result in dementia and other mental loss in older people.

The abnormal channels are known as enlarged perivascular spaces. Rare in young, healthy adults, they are very commonly seen in the brain scans of older people, and in conditions such as diabetes, Parkinson's disease, and high blood pressure. Researchers have long noted these abnormalities, but until now there has been no research on any links with mental function in old age. The enlarged perivascular spaces might be an indicator of overall brain shrinkage, or they might reflect specific damage to brain tissue around blood vessels.

Dr. Alasdair MacLullich, of the University's Geriatric Medicine Unit, measured mental ability in100 healthy elderly male volunteers from the Edinburgh area. Professor Joanna Wardlaw, from the Brain Imaging Research Centre for Scotland, measured the extent of the enlarged perivascular spaces in these men using a new and innovative method of analysis. The team, which also included researchers from psychology and endocrinology, found that men with more enlarged perivascular spaces had worse mental ability.

Dr. MacLullich commented: "These findings mean that we should certainly be looking more closely at enlarged perivascular spaces as a cause of dementia and other mental decline in old age. They raise the interesting possibilities that there may be substances in the blood, such as cholesterol or sugar levels, or even blood pressure itself, that may contribute to memory decline as people become older. This puts a spotlight on blood vessels, so we are now working to find out how these changes around the brain's blood vessel supply arise."