My inbox flooded with links to the report released by NIH (and evangelized by TIME) stating that lifestyle interventions (diet, physical activity, mental exercises, etc.) may not be that effective in preventing Alzheimer's Disease. Before I mount my full counterattack, I need to carefully read through the studies the meta-analysis cites. Still, a quick glance at the exclusion criteria of the meta-analysis reveals the authors limited their review to studies using patients over the age of fifty. So really, these results imply that lifestyle modifications may not prevent, delay, or treat Alzheimer's Disease if you start these changes later in life.
My second point is that all lifestyle modifications are not created equal. Scientific evidence in animal studies suggests that of all interventions, aerobic exercise is our best chance of staving off cognitive decline. In fact, this meta-analysis also found some correlation between exercise and preserving or improving cognitive ability.
There's a good article in The Economist that discusses the failures of the drug industry to find a solution to treating Alzheimer's Disease. One particular quote resonates with my feelings on the NIH report:
Another fundamental problem is that, whatever is causing the damage, treatment is starting too late. By the time someone presents behavioural symptoms, such as forgetfulness, his brain is already in a significant state of disrepair. Even a “cure” is unlikely to restore lost function.