Researchers have discovered that HDL cholesterol can slow the laying down of beta-amyloid plaques that are characteristic of Alzheimer's.

And an early tell-tale sign is a poor memory in middle age, as researchers discovered when they assessed the mental acuity and HDL cholesterol levels of 3,673 civil servants.

They discovered that people with low levels of HDL cholesterol were 53 per cent more likely to suffer memory loss compared with those with the highest HDL levels. And those with impaired memory have a much greater chance of developing dementia and Alzheimer's in later life.

HDL levels can be raised by eating a diet rich in healthy fats such as olive oil.

(Source: Arteriosclerosis, Thrombosis, and Vascular Biology, 2008; June 30, 2008; doi: 10.1161/ATVBAHA.108.163998).