Very high levels of HDL cholesterol, which is often considered healthy, are apparently associated with an increased risk of dementia. This finding not only improves understanding of dementia in general, but could also help identify people at potentially increased risk of dementia.
A new study involving experts from Monash University examined whether high plasma levels of HDL cholesterol are associated with an increased risk of dementia in older people. The results were published in the journal “The Lancet Regional Health – Western Pacific”.
Study had over 19,000 participants
The research included 16,703 people aged 70 or over who came from Australia. There were also 2,411 participants aged at least 65 years from the USA.
The new research is one of the largest studies to date on elevated HDL cholesterol levels and dementia in originally healthy older people, the team reports.
Sometimes very high HDL cholesterol levels
At the start of the study, the participants did not suffer from any diagnosed cardiovascular diseases, dementia, physical disability or life-threatening illnesses. In addition, all participants were classified as cognitively healthy. A total of 2,709 participants had very high levels of HDL cholesterol at the start of the study.
A total of 38 people under the age of 75 who had very high HDL cholesterol levels developed dementia during the study. According to the team, there were 101 cases of dementia in people over the age of 75 with very high HDL cholesterol levels.
Risk of dementia significantly increased
In an average medical observation period of 6.3 years, it was shown that participants who had very high levels of HDL cholesterol (>80 mg/dL or >2.07 mmol/L) at the start of the study had a 27 percent higher level had a greater risk of dementia than participants with optimal HDL cholesterol levels.
On the other hand, if the participants were at least 75 years old, the risk of developing dementia increased by 42 percent, the experts add.
What are optimal HDL cholesterol levels?
In general, HDL cholesterol levels of 40 to 50 mg/dL or 1.03 to 1.55 mmol/L are considered optimal for men, whereas the optimal value for women is 50 to 60 mg/dL or 1.55 to, according to the researchers 2.07 mmol/L. A corresponding level of HDL cholesterol is generally considered to be beneficial for heart health.
The team explains that such high levels of HDL cholesterol, which were associated with an increased risk of dementia in the new study, are rather unusual and cannot be attributed to diet. Rather, they are a feature of a metabolic disorder.
According to the experts, the study results could help to improve the understanding of the mechanisms behind dementia in the future. However, further research is needed to explain why a very high HDL cholesterol level can influence the risk of dementia, emphasizes study author Dr. Monira Hussain.
“While we know that HDL cholesterol is important for cardiovascular health, this study suggests that we need further research to understand the role of very high HDL cholesterol in brain health,” adds the Doctor added in a press release.
In general, according to the expert, it could make sense to take very high HDL cholesterol levels into account in prediction algorithms for the risk of dementia in the future. (as)