New research suggests that high levels of so-called “good” HDL cholesterol not only reduce risk of heart disease but also may help prevent loss of memory. Such loss of memory often precedes the development of dementia such as Alzheimer’s in the elderly.

Alzheimer’s causes a progressive loss of memory and mental faculties, which can be devastating for the patients concerned and those around them.

The study, published in the July 1 edition of the American Heart Association’s journal Arteriosclerosis, Thrombosis and Vascular Biology, measured HDL cholesterol levels of 3,673 British civil servants aged 55 who were given short-term memory tests between 1995 and 1997 and again between 2002 and 2004. The tests consisted in reading a list of 20 words and then writing down as many as the volunteers could remember within two minutes.

Archana Singh-Manoux, the lead author and a senior research fellow at University College London and the French National Institute for Health and Medical Research (the French equivalent of the U.S. National Institutes of health) and colleagues found that, at age 55, those with low levels of good cholesterol were 27 percent more likely to have memory loss than those with high levels. The gap became even more visible in time, as memory problems were 53 percent more common in those with the least HDL by the time they hit age 60. High levels of HDL cholesterol were defined as 60 mg/dL or higher.

Cholesterol is a fatty substance made naturally by the body and also found in many foods. HDL cholesterol is opposed to low-density lipoprotein (LDL) cholesterol, which can build up in artery walls, making them hard and narrow. On the other hand, HDL cholesterol takes excess cholesterol back to the liver. That’s the reason why LDL cholesterol is also called “bad” cholesterol.

Given the study’ results, Singh-Manoux warned that “we are facing a dementia time bomb,” “considering the way the population is aging – the 65-plus age group being the fastest-growing age group,” Reuters quotes him.

That’s why many studies have tried lately to identify risk factors that may appear years before the onset of dementia to help find ways to prevent or postpone it. A study released at the beginning of June by researchers at the Johns Hopkins Bloomberg School of Public Health warned that the number of patients with Alzheimer’s disease will grow in the next years and will reach more than 106 million by 2050.

The biggest jump is projected for densely populated Asia, home of almost half of today’s Alzheimer’s cases, 12.6 million. By 2050, Asia will have 62.8 million of the world’s 106 million Alzheimer’s patients, the study projected.

What is there to be done? The researchers encourage people to have a healthy diet, as good and bad cholesterol levels can be controlled with diet and exercise. For example, whole grains such as oats and oily fish can encourage production of good cholesterol.

However significant the findings are, they “should be approached with caution,” Anatol Kontush, research director at the French National Institute for Health and Medical Research, warned in an accompanying editorial. “In the brain, we are far from that understanding. We need much more basic information before going in to modify levels.”