While exact statistics are hard to come
by, it is generally estimated that about 80% of all dementia in
persons over age 65 is caused by two irreversible disorders.
Alzheimer's disease, by far the most common, is a disease of unknown
cause associated with progressive dementia leading to death within 5
to 10 years. At autopsy, the brain shows characteristic microscopic
abnormalities in the cerebrum, the largest "intellectual" part of the
human brain. Though many tantalizing research leads are under
exploration, there is as yet no treatment for this condition proven to
be effective. The other major cause of irreversible dementia among the
elderly is a phenomenon usually known as multi-infarct dementia,
meaning many small strokes that destroy small areas of brain tissue.
Theoretically, the treatment of existing high blood pressure might
help in preventing further "mini-strokes", but the treatment of
hypertension in the elderly can be very tricky since "over-treatment"
can also lead to brain damage due to insufficient blood flow. That is
the bad news. The relatively good news is that approximately 10 to 20%
of persons over 65 years of age with mental deterioration have
underlying causes that may be partially or completely reversed,
including the following:
- Inappropriate drug ingestion: This "cause" is put at the top
of the list to emphasize the increasing recognition of the phenomenon
of excessive and inappropriate drug use by the elderly. Some of this
use stems from the problems of dementia itself (forgetfulness as to
when the last dose was taken, confusion about how long medication
should be taken) or a tendency to try something suggested by a friend.
However, much of the blame must be laid at the doorstep of physicians
who too readily prescribe drugs without careful checking as to what
the person is already taking, or who spend too little time to consider
(and explain) the special problems that many common drugs might cause
older people. Indeed, one of the first steps in evaluating the
development of dementia in anyone is to review all drug use carefully,
including non-prescription drugs. In some cases it may be necessary to
check the medicine cabinet at home rather than rely on the verbal
report given. The discontinuation of drugs should be done under the
supervision of a knowledgeable physician, since serious withdrawal
problems can occur.
- Unrecognized depression: As with persons of any age, serious
underlying depression may be missed in the midst of intellectual
deterioration. But there is a special danger of this happening to an
elderly person, given the easy explanation of "senility" for such
deterioration and the erroneous assumption that elderly persons are
not likely to become depressed. Indeed, during depression they are
more likely to deny mood changes and instead focus on bodily
complaints. But depression is being increasingly identified as the
basis for impaired mental function in elderly people, and proper
treatment can lead to striking improvement.
- Underlying physical disease: This category is all-inclusive
and runs the gamut from alcoholism to infection to low thyroid
function to an unrecognized blood clot next to the brain.