High 'Bad' Cholesterol Levels Linked To Early-Onset Alzheimer's

A rare form of Alzheimer's disease that manifests at an atypically young age has been linked to high levels of LDL 'bad' cholesterol. The findings were revealed in a new study out of Emory University and Atlanta Veterans Affairs Medical Center, where researchers looked at specific genomic regions of more than 2,100 people. In addition to detailing a link between 'bad' cholesterol and the rare form of Alzheimer's, the study also reveals a possible new genetic risk factor.

Past research has revealed a link between high LDL 'bad' cholesterol levels and late-onset Alzheimer's disease, which happens after the age of 65 and is the most common manifestation of the condition. Early-onset Alzheimer's is less common and involves the development of symptoms before the age of 65. Around 10-percent of early-onset Alzheimer's cases can be explained by gene variants, according to the new study.

The gene variants PSEN1, PSEN2, and APP have been linked to the early-onset variety of this disease, though around 90-percent of these cases ultimately have unexplained causes. The new study looked into both high LDL cholesterol levels and genetic variants in relation to early-onset Alzheimer's disease.

During their work, the researchers found an association between high levels of 'bad' cholesterol and the likelihood of developing early-onset Alzheimer's. The same link was not found between high levels of HDL 'good' cholesterol and this variety of the disease. As well, the team says that triglyceride levels and Alzheimer's had a 'very slight' link.

In addition to the cholesterol link, the study also reveals an association between a gene variant called APOB, which is described as rare, and the development of Alzheimer's at a relatively young age. Study participants who had the disease were more likely to have this gene variant, hinting at a possible genetic risk factor.

Though the findings are an important clue in the effort to unravel Alzheimer's disease, questions remain. Additional research will be necessary to tease apart the relationship between early-onset Alzheimer's, high LDL cholesterol, and how the two are fully connected. The researchers note that investigating this condition is made difficult by the low number of people diagnosed with Alzheimer's at a younger age.