Is This Another Way to Avoid Alzheimer's?

Getting out may save your brain.

Lifespace and Alzheimer's Disease
If you want to get through a long life and remain healthy, you might want to at least check a study done at Rush Medical School's Rehabilitation Unit. It claims that those with greater "lifespace" were on five year follow-up far less prone to Alzheimer's than those who stayed in their narrow unit of home.

http://www.psychologytoday.com/blog/the-power-rest/201105/is-another-way-avoid-alzheimers-0
Published on May 26, 2011 by Matthew J. Edlund, M.D. in The Power of Rest

What's Lifespace?
Basically how much you get out into the neighborhood - walking and getting around, and driving away from where you live.
Who Did Better?
Those who got out the most. Looking at 1294 people, many of whom were in assisted living and started off quite healthy, the diminishment of Alzheimer's disease was up to 75% less in those who got out the most.
Why Would Alzheimer's Be Less Frequent?
Two things at least seem possible factors - physical activity and social engagement. When people move around more they keep their arteries more "clean" and get less Alzheimer's disease.

Social engagement also seems a factor in keeping people healthy, which has been known since Berkman and Syme's Alameda County study, published in 1979. The more people you know and interact with, the better off your physical and mental health. This has been shown with Alzheimer's disease before.
Another factor may be spatial. People learn more when they are in more than one environment. Even college students studying for a test seem to remember better if they periodically move where they study.
And getting out of your home also means more information to the brain. That information has to go somewhere, and improved memory may in part be the result - through the "cognitive challenge" of getting out and visiting.
Are There Counfounding Factors to These Results?
Sure. The study supposedly controlled for social support - but social and environmental engagement is by no means the same thing.
Also, this is a follow up study looking at naturalistic conditions. The people who were slated to avoid Alzheimer's with overall better physical health and cognitive reserve might have been the ones who would get out more anyway.
What Really Causes Alzheimer's?
That's not clear. Part of it appears to be vascular. People with diabetes and high blood pressure get more of it. Keeping your arteries clear and clean also appears to be protective.
Within nerve cells, excess junk seems to accumulate over time which gets harder and harder to rid with aging. Why this happens is not close to fully worked out, with so far just a few protein groups identified.
Reprocessing in cells is a very important factor in preventing the ravages of aging. There may be one billion protein-protein interactions per cell per second. So repairing stuff that's bad or used up has to be done expeditiously - and we know that such reprocessing/renewal is slower with age.
How Can This Help Me?
Though intervention studies need to be done, all the things that come out in this study are doable by people with a modicum of physical health - and should help you in multiple ways.
First, there's the element of physical activity. Walk 20 minutes and you'll grow new brain cells - in the hippocampus a major brain memory area - at night during sleep. So getting out to visit someone or something appears healthy and regenerative in itself.
Second, humans are social animals. The more we're around people - particularly around people with whom we share some bonds, particularly with symphathetic understanding - the less depression and heart disease we seem to have.
Third, think of your body as a giant information processing unit. The more information you process, the better off you may be, as the brain and body have to work to use all that information in order to aid your natural rebuilding - which in turn keeps you healthy. Remember, most of you is replaced in about three to four weeks. We learn in order to live.
And lots of what you learn will be unconscious to you - like your immune system changing its response to different bacteria and viruses as you walk through a parking lot.
Fourth, it's pretty clear that going out in nature, particularly in sunshine, benefits mood and energy. The more you're out the more you'll want to do - and probably be able to do.
Fifth, the brain may respond to novelty alone - so increasing the information flow may itself be beneficial.
So visit your friends, your work colleagues, your acquaintances. Get outdoors and see the world - increasing your "lifespace."