California [US], November 30 : An increased risk of dementia in older persons has been linked to abnormally high levels of HDL-C, also referred to as good cholesterol, according to a Monash University-led study.
Extremely high levels of HDL-C associated with dementia risk were unusual, unrelated to food, and more likely to be indicative of a metabolic condition, according to researchers.
The results could aid medical professionals in identifying an elderly patient population that may be susceptible to dementia, especially those 75 years of age and above.
One of the largest investigations on the relationship between elevated HDL-C levels and dementia among initially healthy older adults, primarily over 70, who were included in the ASPREE* trial, was published in The Lancet Regional Health - Western Pacific.
Over an average of 6.3 years, participants with very high HDL-C (>80 mg/dL or >2.07 mmol/L) at study entry were observed to have a 27 per cent higher risk of dementia compared to participants with optimal HDL-C levels, while those aged 75 years and older also showed a 42 per cent increased risk compared to those with optimal levels.
Very high HDL-C levels were categorised as 80 mg/dL (>2.07 mmol/L) or above. The optimal level of HDL-C of 40 to 60 mg/dL (1.03-1.55 mmol/L) for men and 50 to 60 mg/dL (1.55-2.07 mmol/L) for women was generally beneficial for heart health.
Among 18,668 participants included in this analysis, 2709 had very high HDL-C at study entry, with 38 incidents of dementia in those aged less than 75 years with very high levels, and 101 in those aged 75 and more with very high levels.
First author and Monash University School of Public Health and Preventive Medicine senior research fellow Dr Monira Hussain said that further research was needed to explain why a very high HDL cholesterol level appeared to affect the risk of dementia.
Dr Hussain said these study findings could help improve our understanding of the mechanisms behind dementia, but more research was required.
"While we know 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 the context of brain health," she said.
"It may be beneficial to consider very high HDL cholesterol levels in prediction algorithms for dementia risk."
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