I'm surprised no one has mentioned APOE-e4 yet. Because it's too obvious?
Anyway, you can get your 23&me done for like $200. Some of the SNPS they check out are your APOE alleles.
Two copies of APOE-e4, greatly enhanced Alzheimer's risk, and enhanced early onset risk.
One APOE-e4 and one APOE-e3: enhanced risk
Two APOE-e3: low risk
One APOE-e3 one APOE-e2: very low risk
APOE-e4 and APOE-e2: about the same as two APOE-e3, maybe a little higher
Two APOE-e2 very very low risk, but maybe an enhanced chance of something else (forget what it was).
There's some other genes in the readout that affect Alzheimer's risk, which you can see if you take your results over to Promethease.
Other than that, men are are a fair amount less likely to get it than women. You can google around to find the exact numbers.
I know this isn't exactly what you asked for, but these genes affect the risk so much that if you're in a low risk category genetically, you can pretty much ignore the possibility entirely. If you're in a high risk category, get a good night's sleep for the rest of your life, exercise, and avoid diabetes at all costs.
If you've got a family history of dementia, it's worth checking.
