Encyclopedia of Health and Medicine

dementia 251
metabolic disruptions that are the hallmark of
withdrawal from prolonged ALCOHOL INTOXICATION
(delirium tremens). Other metabolic disturbances,
such as occur with LIVER FAILURE (hepatic
ENCEPHALOPATHY) or ketoacidosis of DIABETES, also
cause delirium. Some people experience delirium
as a reaction to general ANESTHESIA or certain medications,
or as a consequence of very high FEVER.
People who are elderly are more vulnerable to
delirium, though delirium may occur at any age.
The presentation of delirium, which varies
widely, is often difficult to distinguish from that of
disorders such as DEMENTIA. A person experiencing
delirium may exhibit DELUSION, HALLUCINATION, disorientation,
restlessness, and inability to concentrate.
The person’s recent health history, including
history of substance abuse or ALCOHOLISM, generally
provides the determining information. BLOOD
tests may show electrolyte or GLUCOSE (sugar)
imbalances. The diagnostic path focuses on finding
the underlying cause. Delirium nearly always
resolves when the doctor identifies and treats the
underlying cause.
See also COGNITIVE FUNCTION AND DYSFUNCTION;
PSYCHOSIS.
dementia The loss of cognitive function resulting
from changes in the structure of or damage to the
BRAIN. Metabolic disturbances that create biochemical
imbalances in the body, such as chronic CIRRHO-
SIS, may alter the brain’s biochemistry as well,
establishing transient dementia (dementia that
goes away when the underlying imbalance returns
to normal). An ADVERSE REACTION to medication or
interaction among medications may also produce
symptoms of dementia that typically end when the
person stops taking the medication. Most often,
however, dementia represents permanent loss of
abilities related to thought, memory, logic, analysis,
calculation, planning, and organization.
Degenerative neurologic disease ALZHEIMER’S DIS-
EASE, PARKINSON’S DISEASE, HUNTINGTON’S DISEASE, and
other progressive, degenerative conditions affecting
the brain are the primary causes of dementia.
These conditions cause the death of neurons in
areas of the brain that conduct cognitive activities
and are the most common causes of dementia.
Lewy body dementia Lewy bodies are abnormal
protein deposits that form in the structures of
the midbrain. Because the midbrain handles functions
related to basic emotional response (such as
fear and anger) and basic motor function, Lewy
body dementia typically produces symptoms that
appear a blend of Parkinson’s disease and
Alzheimer’s disease. Some researchers believe the
three conditions may share common origins,
though the mechanisms of their relationship
remain undetermined.
Vascular dementia STROKE, TRANSIENT ISCHEMIC
ATTACK (TIA), BRAIN HEMORRHAGE, carotid ATHERO-
SCLEROSIS, and cerebral vascular disease (atherosclerosis
affecting the arteries within the brain)
deprive areas of the brain of the BLOOD supply they
require to remain functional. Brain neurons can
survive only a short time (three minutes or less)
without oxygen; the body cannot replace lost neurons
as it can certain other types of cells.
Traumatic brain injury Injury to the brain
such as may occur in MOTOR VEHICLE ACCIDENTS may
permanently damage areas of the brain. TRAUMATIC
BRAIN INJURY (TBI) is the most common cause of
dementia in people under age 60. Depending on
the extent and location of the injury, it is sometimes
possible to retrain other areas of the brain to
carry out some of the lost cognitive functions.
Symptoms and Diagnostic Path
The symptoms of dementia may appear gradually
or suddenly depending on the cause. They typically
include
• loss of memory, which may manifest in terms
of forgetfulness, failure to recognize familiar
people and places, and inability to carry out
familiar activities such as cooking or driving to
the store
• inappropriate behavior, such as outbursts of
anger
• inability to find the right words when speaking
• personality changes
• inability to make basic decisions, such as which
shirt to wear or what to eat
• pronounced decline in PERSONAL HYGIENE
(bathing and wearing clean clothes)
The diagnostic path begins with a comprehensive
medical examination to look for common and