Your cholesterol levels starting in middle age may contribute to the risk of developing dementia (impairment of brain functions) years later, according to a new study published in the journal The Lancet Healthy Longevity.
Researchers looked at data from a group of United Kingdom residents ages 40 and older, with a first cholesterol reading recorded between 1992 and 2009. Participants had their cholesterol levels recorded periodically, through lab tests scheduled according to normal recommendations, until early 2015, or potentially earlier when a person developed dementia, died, transferred out of a participating doctor practice, or stopped having their cholesterol measured. People with a dementia diagnosis before the initial cholesterol reading were excluded from the study. The researchers then looked at the relationship between total cholesterol, HDL (high-density lipoprotein, or “good”) cholesterol, LDL (low-density lipoprotein, or “bad”) cholesterol, and triglyceride levels, and the risk of being diagnosed with dementia during the study period.
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When looking at the results, the researchers adjusted for many different factors that could affect the risk of developing dementia, including age, sex, ethnicity, income status, location, smoking status, alcohol intake, and body-mass index (a measure of body weight that takes height into account). They also divided the results into different groups based on participants’ age at the time of their first cholesterol measurement (under age 65, or 65 and above) and duration of follow-up (less than 10 years, or 10 years or longer).
Higher LDL linked to greater dementia risk
Overall, the researchers found a link between higher LDL cholesterol and a greater risk of developing dementia, with a 5% higher dementia risk based on an LDL cholesterol increase of a statistical unit called a standard deviation (SD). For people under age 65 at the beginning of the study, every SD increase in LDL cholesterol was linked to a 10% higher risk for dementia diagnosed within the first 10 years, and a 17% higher risk for dementia diagnosed after 10 years. For people age 65 or older at the beginning of the study, every SD increase in LDL cholesterol was linked to a 3% higher risk for dementia diagnosed within the first 10 years, and a 7% higher risk for dementia diagnosed after 10 years. In other words, having higher LDL cholesterol at an age younger than 65 was a better predictor of dementia than higher LDL cholesterol over age 65 — and it was especially good at predicting dementia after 10 years or longer in this group.
The researchers found a weaker link between total cholesterol and the risk for dementia, and no consistent link between either HDL cholesterol or triglyceride levels and dementia risk.
“LDL cholesterol should be added to the list of modifiable risk factors for dementia,” the researchers concluded. They noted that the latest study is the largest on this topic to date, and that the results appear to clarify the relationship between LDL cholesterol and dementia risk after inconsistent findings in earlier, smaller studies. But, they added, confirming that lowering your LDL cholesterol reduces the risk of developing dementia “might require follow-up beyond 10 years, with reliable measures to capture dementia, in large, randomised trials.”
Want to learn more about maintaining cognitive health with diabetes? Read “Nine Tips to Keep Your Memory With Diabetes,” “Keeping Your Brain Strong With Diabetes” and “Memory Fitness: How to Get It, How to Keep It.”
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