Why did you even think it?
Brit Medical Journal reports on a large and well-constructed experiment to see if weightlifting would help with Alzheimers.
Results were strongly negative and DEADLY. The old folks who lifted weights lost mental ability faster, and suffered more falls and heart attacks than the non-lifting control group.
Twenty five adverse events occurred (eight were possibly related, nine probably related, and eight definitely related) and four serious related adverse events (one hospital admission for exercise induced angina, two injurious falls, and one case of substantially worsening hip pain) in the exercise group; and no adverse events in the usual care group. In the exercise group an adverse event was reported by 23/329 (7.0%, 95% confidence interval 4.7% to 10.3%) participants.
That's just plain scary. Falls are the typical endpoint of Alzheimers.
Why in the fuck did you even THINK that weightlifting would help? It diverts blood and energy FROM the brain. Unlike walking or dancing, weightlifting doesn't sync the nervous system and doesn't provide any sensory input except pain and misery and torture and dread.
Among young folks there's a 100.00% correlation between weightlifting and absolute brainless stupidity. I don't know the direction of causality, but when you see a 100.00% correlation you've got to be CAUTIOUS at the very fucking least.