According to Harrison's Principles of Internal
Medicine, dementia is a syndrome with many causes. The term is applied when
a "deterioration in cognitive abilities impairs the previously successful
performance of normal activities" in your daily life. Memory is the most
common and most important cognitive ability that is lost.
The most common cause of dementia is Alzheimer's
disease (AD), making up 50% of all cases. The other 50% is made up of
vascular dementia caused by multiple strokes, alcoholism, Parkinson's disease,
and drug intoxication. The term Alzheimer's disease originally meant
presenile or early onset dementia but it is now used to describe any progressive
dementia with the characteristic pathological changes.
Causes Alzheimer's Disease?
(Alzheimer's disease) is characterized by a progressive process that kills brain
cells and destroys synaptic connections between nerve cells in the brain. The
disease is traditionally characterized by the presence of what are called "neuritic"
or "senile" plaques, neurofibrillary tangles, and the loss of nerve
cells that rely on acetylcholine as a neurotransmitter as explained below.
of the "neuritic plaques" is composed of beta-amyloid protein (AP),
which is a minor breakdown component of amyloid precursor protein (APP). This
APP normally gets broken down into fragments in the brain, and one of the
fragments can be AP. Excess AP gets deposited and causes the development of the
neuritic plaques. The phenomenon of APP in the brain not being handled properly
and causing AP to form neuritic plaques is considered to be a primary or at
least a very significant cause of dementia.
tangles (tau) look like tangled hair. They consist of spirals (paired helical
filaments) of abnormal protein (an important architectural component of nerve
cells). Tau is like the framework of a house -- the house being the nerve cell.
It does not normally tangle, but when the brain cells inexplicably add phosphate
groups to it, it spirals and tangles.
plaques and tau impair the healthy functioning of nerve cells causing some to
die. The most sensitive ones die first. These are usually the cells that secrete
acetylcholine as a neurotransmitter for communicating with other cells.
The sequence of changes
that occur in the brain with AD can be divided into four basic categories:
events relate to genetic factors and some spontaneous nerve-cell deaths, or
apoptosis. Generally, nerve cells do not and should not die.
events cause synaptic loss, or loss of nerve interconnections. These include
the beta-amyloid problem and cell-architecture (cytoskeletal) and tau
changes, especially of the cholinergic neurons (nerves using acetylcholine
as a neurotransmitter).
events occur when brain cells start dying. They release amino acids like
glutamine which can cause a damaging reaction due to overexcitation of nerve
cells which in turn causes neurotransmitter problems, atrophy and immune
events occur when the death of brain cells also causes inadequate
circulation and nutrition in the brain.
prevalence of AD goes up rapidly with age. If you live long enough, your chance
for developing AD could be more than 50% (see below). Since people today
are living longer, AD is increasing rapidly. The number of deaths from AD in
1993 were 20 times those in 1979.
60 to 65
years 0.4% to 1%
85 to 90
years 20% to 40%
The nerve-cell loss that occurs with the onset of
AD might start at around age 40, but by the time the person shows symptoms at
age 60 to 70, a large percentage of the damage has already been done. That means
that prevention is your best weapon in the fight against this disease.
There are a number of other possible risk factors
associated with Alzheimer's disease. The most common and generally acknowledged
are family history, genetics, sex (risk is higher in females), Down's syndrome
and aluminum. Late
onset AD is probably more a lifestyle / environmental disease, perhaps with some
genetic tendencies, as opposed to early onset AD, which definitely has a high
Alzheimer's disease is expected to cost the
United States $100 billion in nursing, research, treatments and Medicare
expenses, etc. by the year 2010.
For information on natural treatments for Alzheimer's
Disease, see Flower Power for Alzheimer's Sufferers.
Also see: Aluminum and Alzheimer's.
Also see: Water:
The Misunderstood Nutrient