The Unexpected Way Your ‘Good’ Cholesterol May Affect Your Alzheimer’s Risk

We all know that it’s important to control your cholesterol, but the focus tends to be on the so-called “bad cholesterol” or LDL cholesterol. For most folks, their “good cholesterol” or HDL cholesterol, isn’t part of the equation — but a new study suggests that’s not exactly right.
The study, which was conducted by researchers at the University of Pittsburgh and published in the Journal of Clinical Endocrinology and Metabolism, looked at the HDL cholesterol in 503 middle-aged women. The data found that having larger HDL particles is linked to an increased likelihood of Alzheimer’s disease.
HDL cholesterol is grouped into three sizes: small, medium and large, study author Dr. Samar R. El Khoudary told HuffPost via email. “Smaller particle size during midlife was associated with better cognition level,” El Khoudary said.
Researchers found that after menopause, large HDL particles tend to increase in a woman’s body. These larger HDL particles are not protective against Alzheimer’s disease like their smaller HDL particle counterparts.
“We were able to show that as early as midlife, women who have more of the smaller-sized particles … over the menopause transition are more likely to experience better episodic memory later in life,” El Khoudary said in a press release.
To reach their conclusion, researchers examined volunteers over the course of 16 years, and assessed the cognitive function of study participants and compared that to their HDL particles and HDL function throughout that time.
Dr. Rudy Tanzi, the director of the McCance Center for Brain Health at Massachusetts General Hospital, said “the smaller HDL particle size is associated with better performance on the memory test” and added that these findings are consistent with previous studies that suggest that small-sized HDL particles are protective against amyloid plaque formation in the brain, which is key for protection from Alzheimer’s. Tanzi is not affiliated with the study.
“We now know that the debate is over, the faster you make amyloid in your brain, over a decade or two or three, the sooner you get Alzheimer’s disease. Amyloid is what triggers the disease,” he explained.
This study does have limitations, though. First, it only looked at women, so it’s hard to know if the same could be said for the entire population or if there’s a mechanism that occurs in women’s aging process that affects this outcome.
Second, larger HDL particles are mostly required for clearing cholesterol from the blood, explained Tanzi. So, in this case, there may have been less of a need for larger HDL particles if the women who scored higher on the cognitive tests just had lower cholesterol overall.
“So, all of this might simply point to keeping your cholesterol in check,” Tanzi said.
There are habits you can practice now to lower your risk of Alzheimer’s disease, and many of them likely overlap with the behaviors you do for holistic health. “We always have said, what’s good for the heart is good for the brain,” Tanzi said.
“First thing I would do is diet — stay away from the high-fat, ultra-processed foods, try to stick with whole foods,” Tanzi explained. “Try to have as much fiber and plant-based diet as you can.”
Additionally, aim for at least 150 minutes of exercise per week, he said. “It doesn’t have to be aerobic, just get your heart rate up, just get blood flow going,” Tanzi said. Not smoking is another way to decrease your risk.
While it’s never too late to start living a healthier lifestyle, the sooner you start the better.
“The fact that we saw these associations beginning as early as midlife is really exciting, because finding potential new avenues for Alzheimer’s disease prevention is very important,” El Khoudary added.
If you have high cholesterol it’s important that you manage it, whether that is through lifestyle modifications or medication. While this study focused on HDL cholesterol, it’s also established that LDL cholesterol (or the “bad cholesterol”) increases Alzheimer’s disease risk, too.
While some people are hesitant to take cholesterol medication, it’s an important thing to do for both your heart and brain health if you need it. According to Tanzi, if you do a meta-analysis of the studies that have been done on the relationships between Alzheimer’s and statin medications (statins are a commonly prescribed medication for cholesterol), you’ll find that statins are associated with a decreased risk of the disease.
“Because statins make you more heart healthy … less cholesterol in the body, and that makes your brain healthy,” Tanzi explained.
It’s also important to monitor your own health and watch for signs of Alzheimer’s disease. If you notice that you’re forgetting new information, asking the same questions, having trouble doing regular tasks or struggling to join conversations, you should talk to your doctor.
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Lifestyle changes and medications can help slow the progression of the disease, so it can be powerful to know your diagnosis, too.