Elevated Cholesterol Levels Significantly Increase Risk for Dementia

With both a good and bad side, cholesterol could be considered the Jekyll and Hyde of medicine. As Dr. Jekyll, it makes new cells and hormones, helps digest fats from food, and converts to vitamin D in the skin when exposed to sunlight. But as Mr. Hyde, it slowly builds up as plaque in the inner walls of the arteries, eventually restricting or blocking the supply of blood to the heart, resulting in heart disease or a heart attack. Those same narrowed arteries can also prevent proper blood flow to the brain, depriving cells of vital oxygen. As brain cells die, mental function suffers. So, does that mean high cholesterol increases the risk of developing dementia later in life? According to a new study, yes—even for those with slightly elevated levels.

The study, conducted by researchers at Finland’s University of Kuopio and Kaiser Permanente’s Division of Research, followed 9,844 northern California residents aged 40 to 45 for as long as 40 years. By the end of the study, 598 of them had developed either Alzheimer’s disease or vascular dementia, when they were between the ages of 61 and 88. That equates to a 66 percent increase in dementia risk for those with high cholesterol (240 or higher), and a 52 percent higher risk for those with borderline high cholesterol (200 to 239). “Our study shows that even moderately high cholesterol levels in your 40s puts people at greater risk for Alzheimer’s disease and vascular dementia decades later,” said co-author Rachel Whitmer. “Considering that nearly 100 million Americans have either high or borderline cholesterol levels, this is a disturbing finding.”

The study did not include a breakdown of HDL “good” and LDL “bad” cholesterol for the participants because the significance of these different types of lipids was not widely understood 40 years ago. But Whitmer says it is safe to assume that if their total cholesterol was high they had high levels of bad cholesterol since about two-thirds of total cholesterol reflects LDL.

Previous studies have linked heart and brain health, but this is the first to examine the association between borderline cholesterol levels and dementia. And although dementia typically doesn’t develop until later in life, “it’s a disease of a lifetime and we need to think about it like we do for cardiovascular disease,” said Whitmer. “These people were between 40 and 45 years old when their cholesterol was measured. That is many years before one would get dementia. This is a modifiable risk factor that can be changed.”

Lifestyle changes such as a healthy diet and exercise can help naturally lower cholesterol levels, as can drugs known as statins, including Pfizer’s Lipitor and AstraZeneca’s Crestor. Lead author Dr. Alina Solomon said “keeping your weight down, eating right and getting regular exercise can keep your heart healthy as you age, and it may also keep your brain sharp.”

Other experts agree that it is becoming increasingly evident that lifestyle influences the risk for dementia, even for those who have a genetic disposition for the disease. “We can’t really say how much of risk is lifestyle and how much is genetic,” said Alzheimer’s Association Chief Medical and Scientific Officer Dr. William H. Thies. “We know that most patients with Alzheimer’s also have vascular disease and that the risk factors for vascular disease are modifiable with lifestyle.”

The study appears in the journal Dementia & Geriatric Cognitive Disorders.