People with one allele pairing appear less likely to
develop the disease, and those with other allele
pairings seem more likely. Researchers believe
there are other genes that may affect a person’s
GENETIC PREDISPOSITION for Alzheimer’s disease,
though developing the disease is an interaction
among environmental factors, such as the individ-
ual’s overall health status and lifestyle habits, and
genetic factors.
Early-onset Alzheimer’s disease, in which
symptoms appear before the age of 60 (often in
the 40s and 50s), is the only form of Alzheimer’s
disease researchers know for certain is hereditary.
It occurs as a result of mutated genes on chromo-
somes 1, 14, and 21 that cause alterations in pro-
teins that have key functions in the brain in
regard to regulating amyloid. The mutations occur
in an autosomal dominant INHERITANCE PATTERN,
which means each child of a person who has the
gene mutation has a 50 percent chance of inherit-
ing the gene. In this form of Alzheimer’s disease,
also called familial Alzheimer’s disease, it appears
that inheriting any one of the mutated genes
establishes the certainty of developing the disease.
Researchers are sure that variables of personal
health play a significant role in whether any given
individual develops the disease, though they do
not yet know what those variables are.
Symptoms and Diagnostic PathEarly symptoms of Alzheimer’s disease tend to be
vague and inconsistent deviations from the
known and familiar. Though memory loss is the
most familiar symptom, it is more than simply
misplacing one’s car keys or forgetting an appoint-
ment. A person may travel the same route to and
from the store, for example, and then become
completely lost. Early symptoms that can suggest
Alzheimer’s disease include
- confusion when following directions
- forgetting familiar people and places
- inability to write a check or count out money
to pay for purchases - repeatedly asking the same questions or telling
the same information - inability to prepare meals or perform common
household tasks- stops speaking in the middle of sentences or
conversations
- stops speaking in the middle of sentences or
Later symptoms become more pronounced and
limit independent functioning. Later symptoms of
Alzheimer’s disease include- DEMENTIA
- forgetting to eat or drink
- engaging in socially inappropriate behavior
such as public MASTURBATION - disorientation
- inability to recognize people and places and
sometimes self
The diagnostic path includes a comprehensive
medical examination, thorough NEUROLOGIC EXAMI-
NATION, ELECTROENCEPHALOGRAM(EEG), and usually
imaging procedures such as COMPUTED TOMOGRAPHY
(CT) SCANto rule out other possible causes (such as
BRAIN TUMORor STROKE) that could cause the symp-
toms.
Diagnosis of Alzheimer’s disease is primarily
clinical, as only examination of brain tissue at
autopsy following death can provide definitive evi-
dence of the hallmark amyloid plaques and neu-
rofibrillary tangles. The person’s age, the gradual
progression of symptoms, and ruling out other pos-
sible causes of the symptoms lead the neurologist to
the diagnosis of Alzheimer’s disease. POSITRON EMIS-
SION TOMOGRAPHY(PET) SCANandSINGLE-PHOTON EMIS-
SION TOMOGRAPHY(SPECT) SCANoften can show the
progression of damage within the brain as
Alzheimer’s disease advances. This can help con-
firm the diagnosis and monitor the effectiveness of
medications in slowing the deterioration.Treatment Options and Outlook
In the 1990s the US Food and Drug Administra-
tion (FDA) approved a new class of drugs, acetyl-
cholinesterase inhibitors, to treat Alzheimer’s
disease. These drugs, such as donepezil (Aricept)
and rivastigmine (Exelon), prevent the enzyme
acetylcholinesterase from metabolizing (breaking
down) acetylcholine. This action extends the
length of time acetylcholine remains available to
neurons, compensating to a certain degree for the
diminishing amounts of acetylcholine the brain222 The Nervous System