Types of Dementia

Alzheimer’s disease is the most common form of dementia and is responsible
for 50 percent of all dementias. No direct cause has been identified, but
it is thought that viruses, environmental toxins, and family history are involved.
Definitive diagnosis of Alzheimer’s disease can only be made on autopsy
when neurofibrillary tangles are found in the brain.

Vascular dementia generally affects people between the ages of sixty and
seventy-five. It is estimated that 8 percent of individuals over sixty years old who have a stroke develop dementia within one year. Early treatment of
hypertension and vascular disease may prevent further progression of dementia.
Parkinson’s disease is an insidious, slow, progressive neurological condition
that begins in middle to late life. It is characterized by tremor, rigidity,
bradykinesia, and postural instability. Dementia is also present in 20 percent
to 60 percent of those with Parkinson’s disease. It is characterized by diminishing
cognitive function, diminishing motor and executive function, and
memory impairment.
Lewy body disease is similar to Alzheimer’s disease. Visual hallucinations
and Parkinson’s-like features progress quickly. Lewy bodies are found in the
cerebral cortex. Patients exhibit psychotic symptoms and have a sensitivity
to antipsychotic medications.

Pick’s disease and other frontal lobe dementias are rare and are identified
by changes in personality and emotions, executive dysfunction, deterioration
of social skills, inappropriate behavior, and language problems. Pick’s
disease is most common between ages fifty and sixty. It progresses rapidly
and may be accompanied by apathy, extreme agitation, severe language difficulties,
attention deficits, and inappropriate behavior. Pick’s disease can
only be confirmed on autopsy when Pick’s inclusion bodies are found.
Another disorder that can lead to progressive dementia is Huntington’s
disease, a genetic disorder that usually occurs in middle age. The basal ganglia
and subcortical structures in the brain are affected, causing spasticity in
body movements. Personality, memory, intellect, speech, and judgment are
altered.

Creutzfeldt-Jakob disease (spongiform encephalopathy) is a rare and fatal
brain disorder caused by a virus that converts protein into infectious,
deadly molecules. Early symptoms may be memory loss and changes in behavior.
Creutzfeldt-Jakob disease progresses into mental deterioration, muscle
spasms, weakness in the extremities, blindness, and coma.