Too little of one type of cholesterol has been linked to memory loss and Alzheimer's disease.
Scientists studied more than 3,500 civil servants to investigate how levels of HDL or "good" cholesterol were associated with memory. HDL cholesterol can influence the formation of the beta-amyloid "plaques" that are a distinctive feature in the brains of Alzheimer's patients.
Higher levels of HDL are also believed to protect against damage to blood supply caused by the narrowing of the arteries.
After the five-year study period, the researchers found that people with low levels of HDL were 53 percent more likely to suffer memory loss than people with the highest levels of HDL.
Those with impaired memory are at an increased risk of developing dementia later in life.