Is it possible to have too low a level of cholesterol? A cholesterol profile that reduces the risk of heart disease may increase the risk for Parkinson’s disease - at least for men - researchers report.

Going back several years, studies have uncovered associations between low cholesterol and suicide, stroke, depression, even violence. While the findings in most cases did not stand up to scrutiny, the suspicion remains that very low cholesterol might influence mental function.

Now, at the annual meeting the American Neurological Association held this week in San Diego, California, Dr. Xuemei Huang described a possible link to Parkinson’s disease.

Huang and colleagues, from the University of North Carolina at Chapel Hill, measured the lipid levels of 124 Parkinson’s patients and a group of 112 similar people free of Parkinson’s disease.

Huang reported that, after adjusting for age, smoking, and use of lipid-lowering agents, men with low total and LDL (“bad”) cholesterol levels had an increased risk of Parkinson’s.

For example, compared to men with LDL cholesterol levels higher than 135, those with levels between 91 and 135 were 6 times more likely to have Parkinson’s, and those LDL levels below 91 were 4 time more likely.

Huang proposed several possible mechanisms to explain the link between low cholesterol and risk of Parkinson’s disease. One is that cholesterol helps rid the body of environmental toxins that might trigger Parkinson’s.

“Another possible mechanism underlying our finding is the role of cholesterol as a precursor for hormones/chemical modulators that are involved in central nervous system function in a variety of ways,” he said.

The association did not hold true for women. “Our findings of the gender differences are intriguing…the lifetime risk of Parkinson’s disease is about two-fold higher in males than females,” Huang noted.

“The fact that LDL cholesterol levels increase with age in men until 65 years of age, and until 75 years in women, may be relevant to our findings of gender-specific association between cholesterol and Parkinson’s disease,” he commented.

Expanding on this point, Huang concluded: “The fact that cholesterol levels tend to increase with age in young or middle age adults, yet decrease in later life when the risk of Parkinson’s disease increases, suggests caution in balancing the benefits and risks of medication use in achieving ‘optimal’ cholesterol levels.”