For years, we've all known about, and worried about, the way cholesterol can affect our health. Too much "bad" cholesterol can clog up the arteries, leading to heart attacks and strokes. "Good" cholesterol seems to protect against these problems.

Doctors are also interested in the theory that cholesterol levels could affect how well our brains work as we get older. Unhealthy cholesterol levels might play a part in memory loss during middle age, or even the development of Alzheimer's disease in the elderly.

A new study has looked at 3,673 people with an average age of 55. Everyone had their cholesterol checked and took a memory test where they had to remember a list of 20 words. Five years later, people whose levels of "good" cholesterol had fallen were likely to score lower in the memory test than before.

Medications, diet and exercise can help to control your cholesterol levels. Drugs called statins are often used, and your diet should be low in saturated fats (found in dairy foods and fatty meat) and trans fats (found in some cookies, cakes and fast foods).

However, the researchers didn't look at whether treating unhealthy cholesterol levels could prevent memory loss. Doctors don’t know yet whether improving your cholesterol levels could protect against Alzheimer's disease. Treatment for high cholesterol is still likely to depend on your risk of a heart attack or a stroke, rather than your risk of Alzheimer's disease.

What you need to know. There may be a link between cholesterol levels and memory loss, but the research is at an early stage. Still, it's worth bearing in mind as another reason to keep cholesterol levels healthy.

—Philip Wilson, patient editor, BMJ Group

ConsumerReportsHealth.org has partnered with The BMJ Group to monitor the latest medical research and assess the evidence to help you decide which news you should use.

Read more on ways to keep your memory sharp.