"Good" Cholesterol May Increase Dementia Risk: A Cardiologist Explains Why

A study published in Neurology found that those who had higher and lower HDL ("good cholesterol") values had a higher dementia risk than those with more moderate HDL levels.

To come to this conclusion, researchers used health data from 184,367 participants from the Kaiser Permanente Northern California health plan, all aged 55 or older. They had no indication of dementia prior to initial evaluation between 2002 and 2007. 

The team monitored these participants' cholesterol measurements up until 2020, while noting confounding health factors. 

First off, let's discuss why HDL is considered "good" cholesterol when compared to LDL. 

"HDL is typically referred to as good cholesterol because HDL is typically the format that ushers cholesterol out of the body," explains preventive cardiologist and Founder & CEO of Step One Foods Elizabeth Klodas, M.D.

LDL, on the other hand, settles in the arteries, contributing to clogging and disease risks. "We want most of our cholesterol to be leaving our circulatory system rather than finding a place to park," explains Klodas.

Up until recently, the general consensus was the higher the better for HDL. Studies like this suggest that it's possible to have too much of a good thing.

"Low HDL is a well-established risk factor for heart disease, but high HDL is turning out not to be infinitely protective, and this study falls in line with this evolving understanding," Klodas elaborates. 

While this is an intriguing finding, it's worth noting that most Americans don't have to worry about having HDL levels that are too high. Having high LDL and low HDL is more common, putting 10% of adults over 20 in the U.S.1 at increased risk of heart disease and stroke.

Thankfully, there are lifestyle factors you can utilize in efforts to stabilize your cholesterol—both the good and the bad. Here are a few:

Check your cholesterol: It's important to know where you're starting from, so get your cholesterol levels checked. You can do this at your doctor's office or at home—here's a list of the best at-home tests to consider.

Focus on nutrition: Your diet plays a major role in cholesterol, and you can lower your LDL by making healthy food choices. As Klodas previously told mbg, you'll want to get enough fiber, prioritize plants, keep up with omega-3 consumption, and add antioxidants to your plate when possible. 

A study suggests that both low and high HDL levels may be associated with an increased risk of dementia. While the study didn't find any notable differences between LDL levels and dementia risk, you should still aim to lower unhealthily high LDL levels for overall health benefits.