Behavioral Science

Cognitive Disorders 113
How does dementia differ from the
normal memory changes of aging?
When diagnosing dementia, what other
disorders in your differential are key
to rule out?
What is the prevalence of dementia?
What is the most common type
of dementia?
What is the classical clinical course
for Alzheimer disease?
How does this differ from the course
of vascular dementia?
As we age, we are less able to learn new
information, and we process information
at a slower speed.
However, these changes do not normally
interfere with the basic functioning.
It is crucial that you do not miss a
delirium or a depression. In the elderly,
it is not uncommon for them to report
multiple memory complaints. If you
misdiagnose this as dementia, you will
miss a potentially reversible cause of
memory impairment. Likewise, if you
miss a delirium, you may miss a
potentially serious medical problem.
Additionally, there are several potentially
reversible causes of dementia that you
should look for, including: neurosyphilis,
vitamin B 12 , thiamine, and folate
deficiencies, and normal pressure
hydrocephalus.
Incidence/prevalence increases with
age. The prevalence is approximately
1.5 % in those over 65 years of age. The
prevalence increases to 20% after age 85.
Alzheimer Disease (AD) represents
about 50% to 60% of dementias. The
second most common form is vascular
dementia (formerly multi-infarct
dementia)
Others include front temporal (Pick
and Creutzfeldt-Jakob), Parkinson,
Huntington, and human
immunodeficiency virus (HIV)
dementias.
Slow, gradual onset of memory loss
and cognitive impairment (often there
are problems with judgment, mood
symptoms, and behavioral disturbances
as well). The disease is progressive and
death usually occurs within 3 years
after diagnosis.
Vascular dementia classically has a
stepwise decline, as opposed to the slow
and steady decline in Alzheimer. Onset
of deficits may be abrupt, and with good
control of cardiovascular risk factors the
course may remain relatively stable.