Increased cholesterol levels have been linked to increased risk of Alzheimer’s later in life.
This risk may be due to genetic factors related to cholesterol.
In a study from the Atlanta Veterans Affairs Medical Center and Emory University, scientists found that high levels of LDL cholesterol (‘bad’ cholesterol) in the body may play a causal role in the development of Alzheimer’s disease.
The finding may help doctors understand how the disease develops and find possible treatments.
The study is published in JAMA Neurology. The lead author is Dr. Thomas Wingo, a neurologist, and researcher with the Atlanta VA and Emory University.
Previous studies have found that a major risk factor for Alzheimer’s disease is a specific mutation in a gene referred to as APOE.
The mutation is the largest known single genetic risk factor for Alzheimer’s disease.
This APOE variant, called APOE E4, could raise levels of circulating cholesterol, particularly LDL. This type of cholesterol causes a build-up of cholesterol in the arteries.
But whether there is a causal relation between LDL cholesterol levels in the blood and Alzheimer’s disease risk is a big question.
In this study, the team examined early-onset Alzheimer’s, a relatively rare form of the condition.
The disease appears in people younger than age 65. About 10% of all Alzheimer’s cases are early-onset.
Three specific gene variants (dubbed APP, PSEN1, and PSEN2) are known to be related to early-onset Alzheimer’s disease. APOE E4 is also a risk factor in the disease.
The team examined specific genomic regions of 2,125 people, 654 of whom had early-onset Alzheimer’s and 1,471 of whom were controls.
They also tested blood samples of 267 participants to measure the amount of LDL cholesterol.
The researchers found that APOE E4 explained about 10% of early-onset Alzheimer’s, which is similar to estimates in late-onset Alzheimer’s disease.
The tests for APP, PSEN1, and PSEN2 showed that about 3% of early-onset Alzheimer’s cases had at least one of these mutations.
They also found that participants with increased LDL levels were more likely to have early-onset Alzheimer’s disease, compared with patients with lower cholesterol levels.
The team says LDL cholesterol could be an independent risk factor for the disease, regardless of whether the problematic APOE gene variant is present.
One interpretation of the results is that LDL cholesterol does play a causal role in the development of Alzheimer’s disease.
If that is the case, it is possible to control LDC cholesterol to help reduce Alzheimer’s risk.
The researchers’ current work focuses on confirming the causal link.
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