218 THE (HINA STUDYwork life, perhaps more active than ever. I still enjoy all the same leisure
activities, whether visiting grandchildren, dining with friends, garden-
ing, traveling, golfing, lecturing or making outdoor improvements like
building fences or tinkering with this or that as I used to do on the farm.
Some things have changed, though. Clearly there is a difference between
the seventy-year-old me and the twenty-year-old me. I am slower, not aS I
strong, work fewer hours every day and am prone to taking naps more!frequently than I used to. l
We all know that getting old brings with it diminished capacities
compared with our younger days. But there is good science to show that
thinking clearly well into our later years is not something we need to
give up. Memory loss, disorientation and confusion are not inevitable
parts of aging, but problems linked to that all-important lifestyle factor:
diet.
There is now good dietary information for the two chief conditions
referring to mental decline. On the modest side, there is a condition
called "cognitive impairment" or "cognitive dysfunction." This condi-
tion describes the declining ability to remember and think as well as one
once did. It represents a continuum of disease ranging from cases that
only hint at declining abilities to those that are much more obvious and
easily diagnosed.
Then there are mental dysfunctions that become serious, even life
threatening. These are called dementia, of which there are two main
types: vascular dementia and Alzheimer's disease. Vascular dementia is
primarily caused by multiple little strokes resulting from broken blood
vessels in the brain. It is common for elderly people to have "silent"
strokes in their later years. A stroke is considered silent if it goes un-
detected and undiagnosed. Each little stroke incapacitates part of the
brain. The other type of dementia, Alzheimer's, occurs when a protein
substance called beta-amyloid accumulates in critical areas of the brain
as a plaque, rather like the cholesterol-laden plaque that builds up in
cardiovascular diseases.
Alzheimer's is surprisingly common. It is said that 1 % of people at
age sixty-five have evidence of Alzheimer's, a figure that doubles every
five years thereafter.^48 I suppose this is why we blandly accept "senility"
as part of the aging process.
It has been estimated that 10-12% of individuals with mild cognitive
impairment progress to the more serious types of dementia, whereas
only 1-2% of individuals without cognitive impairment acquire these