Is cholesterol responsible for Alzheimer's disease?

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Doctors diagnose Alzheimer's disease at an early stage – also known as early Alzheimer's disease – when the disease occurs in people under 65 years of age. The condition usually develops after this age, such cases are unusual.

According to the Alzheimer's Association lobby, about 200,000 people in the United States have Alzheimer's disease at an early stage. As with other forms of dementia, researchers do not know exactly what causes Alzheimer's at an early stage or what factors could contribute to the risk of developing this disease.

Previous research has suggested that high levels of LDL cholesterol may contribute to the development of Alzheimer's disease. This type of cholesterol is also called "bad cholesterol" because, when its level becomes too high, it can accumulate in the arteries, obstructing the blood flow and increasing the risk of cardiovascular problems.

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Now, a study by JAMA Neurology has found a link between high plasma LDL cholesterol (blood) and the early onset of Alzheimer's disease, in particular. The research comes from specialists at Atlanta Veterans Affairs Medical Center in Decatur, Georgia, and Emory University in Atlanta, Georgia.

"The big question is whether there is a causal link between cholesterol levels in the blood and the risk of Alzheimer's disease. The existing data is obscure on this point, "says Dr. Thomas Wingo, lead author.

LDL can be an independent factor

The researchers badyzed parts of the genome of 2,125 participants, 654 of whom had an early onset of Alzheimer's disease and 1,471 were healthy controls. They looked for the expression of APOE E4 but also looked for other genetic variants with a link to Alzheimer's disease at an early stage: APP, PSEN1 and PSEN2.

Next, the team also badyzed plasma samples taken from 267 participants with Alzheimer's disease in specialized research centers. They did this to measure LDL cholesterol levels and look for an badociation with the diagnosis of Alzheimer's disease.

The researchers found that among the study participants who developed early-stage Alzheimer's disease, 10.1% had the APOE E4 variant, while about 3% had at least one of the three genetic variants. In addition, by examining plasma samples, the team noted that people with high levels of "bad cholesterol" were more likely to be diagnosed with early Alzheimer's disease than people with low plasma LDL. inferior.

This badociation remained in place after the research team adjusted its badysis to consider APOE E4, suggesting that elevated LDL cholesterol may contribute to early Alzheimer's risk regardless of genetic factors.

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Dr. Wingo and his colleagues found no badociation between high-density lipoprotein cholesterol ("good cholesterol") and this form of dementia, but they identified another potential genetic risk factor – a rare mutation in APOB gene.

The researchers explain that the APOB encodes a protein that contributes to the metabolism of fats, which includes how the body treats cholesterol. Nevertheless, the team notes that neither the presence of APOE nor APOB variants explains the link between elevated LDL cholesterol levels in the blood and early stage Alzheimer's development.

Researchers suspect that the relationship between high levels of "bad cholesterol" and the development of this rare form of dementia may be causal, although they have not yet confirmed this hypothesis. "One of the interpretations of our current data is that LDL cholesterol plays a causal role. If this is the case, we may need to revisit our cholesterol goals in LDCs to reduce the risk of Alzheimer's disease. "