with one possible exception...nicotine.
People with mild-to-moderate Alzheimer's disease who wore nicotine patches for two four-week periods experienced 20 to 80 per cent improved performance on cognition tests. Nicotine works as a neurotransmitter mimic and cognitive enhancer and interferes with the activation of two phospholipases which inhibits the formation of amyloid plaque.
just use the patch instead of cigarettes :)
Interesting. Is there any research showing lower rates of Alzheimer's in smokers? Of course, since Alzheimer's is usually a very late onset disease, it might be hard to document the effects of smoking, since smokers are much less likely to survive to the average Alzheimer's onset age.