Attention 40-year-olds: This may be the time to start thinking about maintaining your brain. One action item: Check your cholesterol.
Recent studies suggest that high cholesterol levels in midlife raise the risk of Alzheimer's and dementia in later life.
"What's good for the heart is good for the mind," says researcher Rachel Whitmer of Kaiser Permanente. Her study, published in the journal Dementia and Geriatric Cognitive Disorders, found that even borderline-high cholesterol levels (200 to 239 milligrams per deciliter) in middle age raised the risk of late-life dementia by about 50 percent.
The study included 9,844 men and women who had their cholesterol measured back in the 1960s and '70s when they were 40 to 45 years old as part of a preventive screening program at Kaiser Permanente of Northern California. Researchers followed these participants for four decades and documented how many were diagnosed with Alzheimer's disease and vascular dementia — a form of dementia caused by problems in blood vessels that feed the brain.
"Our study shows that even moderately high cholesterol levels in your 40s puts people at greater risk for Alzheimer's disease and vascular dementia in later life," says Whitmer.
Does Lowering Cholesterol Prevent Dementia?
The possible link between high cholesterol and Alzheimer's disease might suggest that simply lowering cholesterol can reduce the risk of dementia. But studies suggest there's no clear relationship.
There have been several experiments with people taking cholesterol-lowering statin medications, says Dr. Sam Gandy, associate director of the Alzheimer's Disease Research Center at Mount Sinai School of Medicine. "Unfortunately, so far they've been disappointing," he says. "Despite the fact that in these trials cholesterol has been controlled, we haven't seen the expected impact on later dementia that we would have hoped."
It's possible that people didn't start taking statins early enough in life. Or it's possible that there's some other process that leads to dementia — even when cholesterol and other risk factors are controlled.
Researchers are looking at genetics and at the role of a protein called amyloid beta in the brain. Brain imaging studies show that people with Alzheimer's tend to have abnormal accumulations of amyloid beta in their brains. Yet scientists have not pinpointed how amyloid beta may cause dementia.
"I envision a time where we will treat Alzheimer's disease just the way we treat cholesterol," says Dr. Reisa Sperling, who heads Alzheimer's research at Brigham and Women's Hospital in Boston. She says the goal will be to find agents that lower amyloid beta in the brain. "And we will give them to people in a preventative fashion."
This is the hope for the Alzheimer's medicine — or vaccine — of the future. For now, available drugs help some patients slow the progression of dementia, but they do not treat the underlying pathology of the disease.