Back to general health for a little while: basic good health practices will make a large difference to your future. While it's pleasant to look forward to the high-tech (and not quite so high-tech) future medicine that will extend our healthy life spans, we simply can't afford to assume that the advance of science will be rapid enough or initially affordable enough to save us from the consequences of bad health practices. Why take the chance that you'll be unable to dig yourself out of a hole that you don't have to get into in the first place?
Meanwhile, evidence that physical activity may protect against cognitive loss impresses other experts on aging. A recent study that followed more than 1,700 normal seniors for six years found those who exercised the most -- at least three times a week -- were least likely to develop Alzheimer's disease. One theory, based partly on animal research, is that physical exercise may improve blood flow and oxygen delivery to the brain and increase substances that promote the growth of tissue and blood cells in the hippocampus, a region critical to memory.
The Religious Orders Study, which began in 1993 and includes more than 1,000 nuns, priests and brothers across the country, has found that those who engage more often in reading, puzzles and processing information have a 47 percent lower risk of Alzheimer's disease than those who do little or none.
A research review published in the journal Psychological Medicine found that people who have a significant "brain reserve," or intellectual base, have a much lower risk of developing dementia. "In virtually every study in which we've looked, the more education you have, the lower the prevalence of dementia in that group," said Steven DeKosky, director of the Alzheimer's Disease Research Center at the University of Pittsburgh.
Hybrid activities -- those combining a mental stimulus with some other action -- are also the subject of scientific interest. "Some of the strongest evidence is for activities that involve physical, mental and social at the same time," said Edgerly. Examples include social dancing and coaching or refereeing a team sport, she said.
A recently published study by Sweden's Karolinska Institute offers a case in point. Researchers who followed 776 normal seniors aged 75 and over for six years found that those who said they took part regularly in mental, physical or social activities had a lower risk of dementia; those who combined all three had the lowest risk. Activities that seemed to confer more protection included political and cultural involvement, attending courses, going to the theater or concerts, traveling, being engaged in charity or church activities, and playing music with others.
A study last month in the Annals of Internal Medicine followed 1,740 people over age 65 for six years. The participants, all of whom had normal cognitive function at the start, initially reported how often they exercised for at least 15 minutes a day -- everything from stretching and walking to cycling, weight training and aerobic exercise. Every two years, they were given tests to determine their cognitive and physical functioning, and were also asked to assess their general health.
Those who exercised the most -- at least three times a week -- had the lowest risk of Alzheimer's, 32 percent less than the others. Also, those who started out with the lowest level of exercise benefited the most. That suggests it's especially important for sedentary people to get moving, said Eric Larson, director of the Center for Health Studies at Group Health Cooperative, a nonprofit health system in Seattle.
This is all nothing new - it's yet more support for what we all know about taking care of ourselves in the long term. Human nature being what it is, however, we all have a time preference for our own length of life. Many find it easy to throw away decades of healthy life in the future through poor habits now ... but with the advance of medical technology, you could be throwing away far more than just a decade or two. Miss the boat on the first steps towards radical life extension and you miss the possibility of centuries of interesting, healthy, ever more wonderful life.