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What is AD? | Dementia | Just the Facts
Causes | Signs | Normal Aging | Treatment
What is Dementia?
Dementia is the loss of mental function in two or more areas such
as language, memory, visual and spatial abilities, or judgement
severe enough to interfere with daily life. Dementia itself is not
a disease but a broader set of symptoms that accompanies certain
diseases or physical conditions. Well-known diseases that cause
dementia include Alzheimer's disease, multi-infarct dementia, Parkinson's
disease, Huntington's disease, Creutzfeldt-Jakob disease, Pick's
disease, and Lewy body dementia. Other physical conditions may cause
or mimic dementia, such as depression, brain tumors, head injuries,
nutritional deficiencies, hydrocephalus, infections (AIDS, meningitis,
syphilis), drug reactions, and thyroid problems. Individuals experiencing
dementia-like symptoms should undergo diagnostic testing as soon
as possible. An early and accurate diagnosis helps to identify reversible
conditions gives patients a greater chance of benefiting from exiting
treatments, and allows them and their families more time to plan
for the future.
Alzheimer's Disease
Alzheimer's disease is the most common cause of dementia, affecting
as many as 4 million Americans. AD is a degenerative disease that
attacks the brain, begins gradually, and progresses at a variable
rate. AD results in impaired memory, thinking, and behavior and
can last from 3 to 20 years from the time of onset of symptoms.
Warning signs of AD are memory loss that affects job/home skills,
difficulty performing familiar tasks, problems finding the right
words, disorientation as to time and place, poor or decreased judgment,
difficulty with learning and abstract thinking, placing things in
inappropriate places, changes in mood and personality, and marked
loss of initiative. In the last stage of AD, patients are unable
to take care of themselves. Recent research has shown links between
particular genes and Alzheimer's disease, but in about 90% of AD
cases, there is no clear genetic link. With the help of standardized
diagnostic criteria, physicians can now diagnose AD with an accuracy
of 85-90% once symptoms occur. However, a definitive diagnosis of
Alzheimer's disease is possible only through the examination of
brain tissue at autopsy.
Multi-Infarct Dementia
Multi-infarct dementia (MID), or vascular dementia, is a deterioration
of mental capacity caused by multiple strokes (infarcts) in the
brain. These events may be described as ministrokes, where small
blood vessels in the brain become blocked by blood clots, causing
the destruction of brain tissue. The onset of MID may seem relatively
sudden, as it may take several strokes for symptoms to appear, These
strokes may damage areas of the brain responsible for a specific
function as well as produce general symptoms of dementia. As a result,
MID is sometimes misdiagnosed as Alzheimer's disease. MID is not
reversible or curable, but detection of high blood pressure and
other vascular risk factors can lead to a specific treatment that
may modify MID's progression. MID is usually diagnosed through neurological
examination and brain scanning techniques, such as a computerized
tomography (CT) scan or magnetic resonance imaging (MRI).
Parkinson's Disease
Parkinson's disease (PD) is a progressive disorder of the central
nervous system that affects over one million Americans. In PD certain
brain cells deteriorate for reasons not yet known. These cells produce
a substance called dopamine, which helps control muscle activity.
PD is often characterized by tremors, stiffness in limbs and joints,
speech difficulties, and difficulty initiating physical movement.
Late in the course of the disease, some patients develop dementia
and eventually Alzheimer's disease. Conversely, some Alzheimer's
patients develop symptoms of Parkinson's. Medications such as levodopa,
which converts to dopamine inside the brain, and deprenyl, which
prevents degeneration of dopamine-containing brain cells, are used
to improve diminished or reduced motor symptoms in PD patients but
do not correct the mental changes that occur.
Huntington's Disease
Huntington's disease (HD) is an inherited, degenerative brain disease
that causes both physical and mental disabilities and usually begins
in mid-life. Early symptoms can vary from person to person but include
involuntary movement of the limbs or facial muscles. Difficulty
concentrating, and depression. Other symptoms include personality
change, memory disturbance, slurred speech, and impaired judgment.
Children born to a person with HD have a 50% chance of inheriting
the gene that causes HD. Today a genetic test is available to confirm
a diagnosis of HD and to identify carriers of the HD gene. It is
recommended that anyone considering genetic testing talk first with
family and/or appropriate medical and counseling professionals.
There is no treatment to stop the progression of HD, but the movement
disturbances and psychiatric symptoms can be treated with medication.
Creutzfeldt-Jakob Disease
Creutzfeldt-Jakob Disease (CJD) is a rare, fatal brain disorder
that causes rapid, progressive dementia and other neuromuscular
disturbances. CJD is caused by a transmissible agent. Research suggests
that the agent differs significantly from viruses and other conventional
agents. This newly discovered pathogen is called a "prion," short
for "proteinaceous infectious particle," because it consists of
protein and transforms normal protein molecules into infectious
ones. The disease can be inherited, but the majority of cases are
not. Early symptoms of CJD include failing memory, changes in behavior,
and lack of coordination. As the disease advances, usually very
rapidly, mental deterioration becomes pronounced, involuntary movements
(especially muscle jerks) appear, and the patient experiences severe
difficulty with sight, muscular energy, and coordination. Like Alzheimer's
disease, a definitive diagnosis of CJD can be obtained only through
examination of brain tissue at autopsy.
Pick's Disease
Pick's disease is also a rare brain disorder characterized by shrinkage
of the tissues of the frontal and temporal lobes of the brain and
by the presence of abnormal bodies (Pick's bodies) in the nerve
cells of the affected areas of the brain. Pick's disease usually
begins between ages of 40 and 60. The symptoms are similar to Alzheimer's
disease, with a loss of language abilities, skilled movement, and
the ability to recognize objects or people. Initial diagnosis is
based on family history (Pick's disease may be inherited), symptoms,
tests, and ruling out other causes of dementia. A definitive diagnosis
of Pick's disease is usually obtained at autopsy.
Lewy Body Dementia
Lewy body dementia (LBD) is an irreversible form of dementia associated
with abnormal protein deposits in the brain called Lewy bodies.
Symptoms of LBD are similar to Alzheimer symptoms and include memory
loss, confusion, and difficulty communicating. Hallucinations and
paranoia also may become apparent in the earlier stages of the disease
and often last throughout the disease process. Although initial
symptoms of LBD may be mild, affected individuals eventually develop
severe cognitive impairment. At this time, there is no treatment
available for Lewy body dementia.
Normal Pressure Hydrocephalus
Normal pressure hydrocephalus is an uncommon disorder, which involves
an obstruction in the normal flow of cerebrospinal fluid. This blockage
causes a buildup of cerebrospinal fluid on the brain. Symptoms of
normal pressure hydrocephalus include dementia, urinary incontinence
and difficulty in walking. Presently, the most useful diagnostic
tools are the neuroimaging techniques (ie., MRI). Normal pressure
hydrocephalus may be caused by any of several factors including
meningitis, encephalitis and head injuries. In addition to treatment
of the underlying cause, the condition may be corrected by a neurosurgical
procedure (insertion of a shunt) to divert the fluid away from the
brain.
Depression
Depression is a psychiatric disorder marked by sadness, inactivity,
difficulty in thinking and concentration, feelings of hopelessness,
and sometimes suicidal tendencies. Many severely depressed patients
will have some mental deficits including poor concentration and
attention. When dementia and depression are present together, intellectual
deterioration may be exaggerated. Depression, whether present alone
or in combination with dementia, can be reversed with proper treatment.
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