High and low HDL cholesterol both linked to slightly increased risk of dementia.

High and low HDL cholesterol both linked to slightly increased risk of dementia.

The Surprising Link Between Cholesterol and Dementia Risk

older female doctor check

Experts say it’s important to keep close watch on your cholesterol levels. FG Trade/Getty Images

A new study has found a surprising link between extreme levels of “good” HDL cholesterol and the risk of developing dementia later in life[^1^]. This groundbreaking research, tracking over 184,000 adults over a period of 17 years, has revealed that both high and low levels of HDL cholesterol are associated with a greater likelihood of developing dementia compared to middle-range levels[^2^].

The study, published in the journal Neurology, aimed to explore the relationship between two types of cholesterol, HDL-C and LDL-C, and the development of dementia in older age[^1^]. While previous studies have touched on this topic, few have considered the influence of statin medications or delved into more complex associations[^1^].

The participants of the study were members of the Kaiser Permanente Northern California health plan, aged 55 and older[^1^]. After taking a health survey between 2002 and 2007, the participants had their cholesterol levels measured within two years of the survey[^1^]. The research team then tracked these individuals until December 2020 to observe if they developed dementia[^1^]. By analyzing extensive data from survey responses and electronic health records, the study aimed to obtain a comprehensive understanding of the cholesterol-dementia relationship[^1^].

The findings of the study revealed that both very low and very high levels of HDL-C were linked to a higher risk of developing dementia[^1^]. Those with the highest HDL cholesterol levels had a 15% increased risk compared to those with mid-range levels, while those with the lowest HDL levels had a 7% increased risk[^2^]. Even after accounting for factors like alcohol use, hypertension, cardiovascular disease, and diabetes, these relationships remained significant[^2^].

Interestingly, there was no clear link between “bad” LDL-C cholesterol and dementia risk, except for individuals who were using statins[^2^]. Only in this specific group, a higher LDL-C level indicated a slightly greater risk of dementia[^2^].

Although this study provides valuable associations, it does not prove that high or low HDL cholesterol levels directly cause dementia[^2^]. Erin Ferguson, MPH, a lead study author, explained that the study revealed a U-shaped relationship between HDL-C and dementia risk, indicating that both lower and higher levels of HDL-C are associated with a slightly elevated risk of dementia[^2^].

The study’s implications are noteworthy, as Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center, says there is a pressing need for studies on dementia prevention, given the modest clinical improvements in current treatments for dementia[^2^]. Segil also highlights the importance of studying the role of statin use in decreasing the risk of multi-infarct or vascular dementia[^3^].

While this study sheds light on the relationship between cholesterol and dementia risk, further research is needed to understand the complex associations and determine causality[^4^]. Erin Ferguson emphasizes the need for future studies to evaluate whether these effects are causal and to identify effective strategies for modifying HDL cholesterol levels[^4^]. Likewise, Cliff Segil suggests that more research should focus on the role of statins in preventing multi-infarct or vascular dementia[^4^].

In conclusion, the surprising link between cholesterol and the risk of developing dementia underscores the importance of maintaining optimal cholesterol levels for overall brain health. While cholesterol management is commonly associated with cardiovascular health, this study highlights the potential impact on cognitive function as well. However, more research is needed to fully understand the mechanisms at play and to develop effective interventions to mitigate this risk. In the meantime, it is crucial for individuals to regularly monitor their cholesterol levels and consult with healthcare professionals to maintain a healthy lifestyle for both heart and brain health.

As a reminder, the three most common dementias are Alzheimer’s dementia, vascular or multi-infarct dementia, and Lewy-Body dementia or Parkinson’s dementia. Statin use, or medication used to lower cholesterol in our blood, has been proven to decrease the risk of a second lifetime heart attack and stroke. Statin use needs to be studied specifically regarding decreasing the risk of multi-infarct of vascular dementia. – Dr. Clifford Segil

While the magnitude of the association is fairly small, these results suggest that the relationship between HDL-C and dementia is complex. Our work supports a body of recent literature showing there are nonlinear relationships between HDL and other diseases (like cardiovascular disease and cancer) and mortality. The mechanisms for why these nonlinear relationships exist are still unknown. – Erin Ferguson, MPH