In a post last August called Alzheimer's vs. Cryonics, I left the following comment:

23andMe recently showed that people of my genotype are more than twice as likely to develop Alzheimer's as others in my ethnic group. I have a 15% chance of getting Alzheimer's before I'm 80, up from 7%. See Patri's post about this.

An initial Googling has generated things like 'eat paleo', 'get caffeine', 'exercise', and 'use your brain'. I'm planning to do further research about decreasing Alzheimer's risk.

I really recommend that everyone do 23andMe for this precise reason.

wedrifid made an insightful response:

I wonder, how much does that single bit of information (doubling the chance) matter to those decisions? Should you have been doing those things anyway, for the Alzheimer's prevention and the other benefits? Is it the motivational factor of the formal personal certification that is important or the actual information?

wedrifid nailed it. Transhumanists have a huge interest in making the necessary lifestyle adjustments to prevent Alzheimer's. Even if cryonics were certain to work, I'd like it to be me that is resurrected when the technology is available, and I won't still be me if Alzheimer's gets its way.

So I've been keeping an eye out for relevant information. I haven't done rigorous research yet, but a friend recently sent me a study: "A molecular link between the active component of marijuana and Alzheimer's disease pathology." I've uploaded the full text of the article here.

A sample from the abstract:

Here, we demonstrate that the active component of marijuana, Delta9-tetrahydrocannabinol (THC), competitively inhibits the enzyme acetylcholinesterase (AChE) as well as prevents AChE-induced amyloid beta-peptide (Abeta) aggregation, the key pathological marker of Alzheimer's disease. [...] Compared to currently approved drugs prescribed for the treatment of Alzheimer's disease, THC is a considerably superior inhibitor of Abeta aggregation, and this study provides a previously unrecognized molecular mechanism through which cannabinoid molecules may directly impact the progression of this debilitating disease.

From the conclusion:

It is noteworthy that THC is a considerably more effective inhibitor of AChE-induced [Abeta] deposition than the approved drugs for Alzheimer’s disease treatment, donepezil and tacrine, which reduced [Abeta] aggregation by only 22% and 7%, respectively, at twice the concentration used in our studies.

Therefore, AChE inhibitors such as THC and its analogues may provide an improved therapeutic for Alzheimer’s disease, augmenting acetylcholine levels by preventing neurotransmitter degradation and reducing [Abeta] aggregation, thereby simultaneously treating both the symptoms and progression of Alzheimer’s disease.

I, for one, would like to know if smoking weed could help prevent a fate that's plausibly worse than death-and-cryonics. So for those who know more about biology than I do: how promising are these results? What else has been shown to help prevent Alzheimer's?