High LDL linked to early-onset Alzheimer's
Elevated cholesterol levels have been linked to increased risk of Alzheimer's later in life, and APOE4 is known to raise levels of circulating cholesterol, particularly low-density lipoprotein (LDL) ("bad cholesterol"). A new study has investigated whether LDL is also linked to early-onset Alzheimer's.
The study involved genetically testing 2,125 people, 654 of whom had early-onset Alzheimer's, and testing for cholesterol in a subset of 267 participants. It found that APOE4 explained about 10% of early-onset Alzheimer's, which is similar to estimates in late-onset Alzheimer's disease. About 3% of early-onset Alzheimer's cases had at least one of the known early-onset Alzheimer's risk factors (APP, PSEN1, PSEN2).
Those with elevated LDL levels were more likely to have early-onset Alzheimer's disease, compared with patients with lower cholesterol levels. This was true even after the researchers controlled for APOE genotype.
There was no link between HDL (high-density lipoprotein) cholesterol levels and early-onset Alzheimer's, and only a very slight association between the disease and triglyceride levels.
The researchers also found a new possible genetic risk factor for early-onset Alzheimer's disease. Early-onset Alzheimer's cases were higher in participants with a rare variant of a gene called APOB. This gene encodes a protein that is involved in the metabolism of lipids, or fats, including cholesterol.
Good cholesterol may cut women’s dementia risk
A long-running study found that women who had normal levels of the “good” cholesterol, HDL, in 1992 had less white matter damage in their brain two decades later.
The data come from 135 participants in the long-running Women's Healthy Ageing Project. The study found that a higher cardiovascular risk score in midlife was associated with a greater degree of white matter hyperintensity lesions 20 years later, but, intriguingly, that this was predominantly driven by HDL cholesterol level, after controlling for age, education, and APOEe4 status.
(2019). Association of Early-Onset Alzheimer Disease With Elevated Low-Density Lipoprotein Cholesterol Levels and Rare Genetic Coding Variants of APOB.
JAMA Neurology. 76(7), 809 - 817.
(2018). The effect of midlife cardiovascular risk factors on white matter hyperintensity volume and cognition two decades later in normal ageing women.
Brain Imaging and Behavior.