Researchers have identified a link between having raised or reduced levels of ‘good’ cholesterol and a slightly greater risk of dementia.
The large-scale study gave researchers the opportunity to examine dementia links across a range of cholesterol levels.
The team studied data from just over 184,000 people with an average age of 70. At the start of the study, none of the participants had dementia.
They answered questions about their health behaviours and had their cholesterol measured an average of 2.5 times within two years. Researchers then followed their health records for an average of nine years.
During the study, just over 25,200 participants developed dementia.
Researchers found a 15% higher rate of dementia among those with the highest levels of high-density lipoprotein (HDL) – ‘good’ cholesterol – compared to the middle group. They also found a 7% higher rate of dementia in people with the lowest levels of HDL.
Study author Maria Glymour, from Boston University, said: “Previous studies on this topic have been inconclusive and this study is especially informative because of the large number of participants and long follow-up.
“This information allowed us to study the links with dementia across the range of cholesterol levels and achieve precise estimates even for people with cholesterol levels that are quite high or quite low.”
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The study findings only showed a small link between ‘bad’ cholesterol – low-density lipoprotein – and dementia risk.
Maria Glymour went on to say: “The elevation in dementia risk with both high and low levels of HDL cholesterol was unexpected, but these increases are small, and their clinical significance is uncertain.
“In contrast, we found no association between LDL cholesterol and dementia risk in the overall study cohort. Our results add to evidence that HDL cholesterol has similarly complex associations with dementia as with heart disease and cancer.”
Read the study in Neurology.