The strongest risk factor is advanced age. Yearly risk for AD is about 1% per year in 70 year old populations jumping to around 7% in 90 year old groups.
Now a recent study is shedding some light on a new risk for AD in men. This risk appears to be related to a chromosome Y phenomenon known to be associated with aging.
Elderly men show a tendency to lose the Y chromosome from a small percentage of cells over time. This phenomenon is known as loss of Y or LOY.
The percentage of blood cells with LOY can be determined. A study recently published in Journal of Human Genetics (see citation below) found significant support for higher percentage of LOY being linked to AD risk.
Here are the key findings:
- In a sample of 3218 elderly men 17% showed evidence of LOY chromosome mosaicism
- LOY percentage rates were strongly positively correlated with older age
- Men with AD had higher rates of LOY than age-matched men without AD (adjusted odds ratio=2.80)
- Two prospective studies found higher rates of incident AD in men with LOY (adjusted odds ratio=6.80)
These findings are not simply minor as the effect of LOY on risk appears similar in magnitude to the strongest genetic risk factor for AD, APOE gene status.
LOY has also been linked to a higher risk of cancer, so it appears to be a non-specific risk factor.
The authors of this study note;
"Regardless of the underlying mechanism(s) for the increased risk of AD and cancer in men with LOY in blood, our and other's published results reinforce a role of factors on chromosome Y in various, still poorly explored biological processes, other than sex determination and sperm production."LOY is not yet a common test in clinical practice. However, I think we will be hearing much more on this association with potential for screening and intervention studies.
Access the free full-text manuscript by clicking on the DOI link in the citation below.
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d sperm production.
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