Is High HDL Cholesterol Always Good? The Surprising Link to Dementia

Updated July 2026

HDL cholesterol has long been celebrated as the "good cholesterol," the kind that clears cholesterol out of the bloodstream and lowers heart risk. So a finding that very high HDL might carry its own risk comes as a genuine surprise. Here's what a notable study found, and how much you should actually make of it.

What did the study find?

That very high HDL was linked to more dementia, not less. A study published in The Lancet Regional Health – Western Pacific tracked 18,668 adults aged 65 and older, all healthy in body and mind at the outset, for more than six years. It found a 27% higher risk of developing dementia in people with very high HDL levels, a result that runs against the conventional belief that more HDL is always better. Before anyone panics, though, this is a single study, and its findings need to be kept in perspective.

What counts as "very high" HDL?

Higher than most people ever reach. For context, an HDL of 40 mg/dL or higher is generally considered healthy for men, and 50 or higher for women; levels below that are consistently tied to greater heart risk. In this study, "very high" meant 80 mg/dL or more, a level that's genuinely unusual in the general population, especially among men and older adults. So this isn't about the person whose HDL is a healthy 55 or 65. It's about the rare, sky-high readings.

Could something else explain the link?

Very possibly, and this is why one study rarely settles anything. The researchers did account for traditional dementia risk factors, including physical activity, alcohol intake, education, diabetes, smoking, and some genetic markers, and still found an independent association. But one important caveat is that alcohol intake was self-reported, which is notoriously unreliable. Heavy drinking is bad for the brain and can raise HDL, so it may have acted as a hidden confounder muddying the picture. It's also true that older people are simply more prone to cognitive decline to begin with, which complicates interpretation further.

So should you worry about your HDL?

Almost certainly not, but the finding is still instructive. Healthy HDL remains a good thing to aim for; it usually signals better overall cardiometabolic health, and low HDL is a clear marker of higher heart risk. The real lesson is subtler: HDL is not infinitely protective, and higher and higher is not endlessly better and better. Remember what HDL actually is: it's the "good" form of cholesterol because it's the form being cleared from the body, but it's still cholesterol. One possibility is that a very high HDL in some people signals a problem with the removal process itself, and that the cholesterol has to go somewhere.

The practical takeaway holds regardless of age or sex: a high HDL does not cancel out a high LDL, for your heart or your brain. Each cholesterol particle has to be judged on its own merit, within your individual clinical picture, ideally with your physician. You can read more about the broader heart-brain connection that underlies all of this.

One last note from our own work. In our clinical trial, we saw only small increases in HDL among people using Step One Foods, the modest bump you'd expect from improving metabolic health, with no dramatic, statistically significant jump. That used to disappoint me. As more findings like this one emerge, I've come to think it may have been exactly the right outcome.

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