21 COGNITIVEDISORDERS 513
Cognition is the brain’s ability to process, retain, and
use information. Cognitive abilities include reason-
ing, judgment, perception, attention, comprehension,
and memory. These cognitive abilities are essential for
many important tasks including making decisions,
solving problems, interpreting the environment, and
learning new information.
A cognitive disorder is a disruption or impair-
ment in these higher-level functions of the brain.
Cognitive disorders can have devastating effects on
the ability to function in daily life. They can cause
people to forget the names of immediate family
members, to be unable to perform daily household
tasks, and to neglect personal hygiene (Caine &
Lyness, 2000).
The primary categories of cognitive disorders
are delirium, dementia, and amnestic disorders. All
involve impairment of cognition, but they vary with
respect to cause, treatment, prognosis, and effect on
clients and family members or caregivers. This chap-
ter focuses on delirium and dementia. It emphasizes
not only care of clients with cognitive disorders but
also the needs of their caregivers.DELIRIUM
Deliriumis a syndrome that involves a disturbance
of consciousness accompanied by a change in cog-
nition. Delirium usually develops over a short pe-
riod, sometimes a matter of hours, and fluctuates or
changes throughout the course of the day. Clients
with delirium have difficulty paying attention, are
easily distracted and disoriented, and may have sen-
sory disturbances such as illusions, misinterpreta-
tions, or hallucinations. An electrical cord on the floor
may appear to them to be a snake (illusion). They may
mistake the banging of a laundry cart in the hall-
way for a gunshot (misinterpretation). They may
see “angels” hovering above when nothing is there
(hallucination). At times, they also experience distur-
bances in the sleep–wake cycle, changes in psycho-
motor activity, and emotional problems such as anx-
iety, fear, irritability, euphoria, or apathy (American
Psychiatric Association [APA], 2000).
An estimated 10% to 15% of people in the hospi-
tal for general medical conditions are delirious at any
given time. Delirium is common in older acutely ill
clients. An estimated 30% to 50% of acutely ill older
adult clients become delirious at some time during
their hospital stay. Risk factors for delirium include
increased severity of physical illness, older age, and
baseline cognitive impairment (e.g., as seen in de-
mentia; Caine & Lyness, 2000). Children may be more
susceptible to delirium especially related to a febrile
illness or certain medications such as anticholiner-
gics (APA, 2000).Etiology
Delirium almost always results from an identifiable
physiologic, metabolic, or cerebral disturbance or dis-
ease or from drug intoxication or withdrawal. The
most common causes are listed in Box 21-1. Often
delirium results from multiple causes and requires a
careful and thorough physical examination and lab-
oratory tests for identification.On a hot and humid August afternoon, the 911 dispatcher
received a call requesting an ambulance for an elderly
woman who had collapsed on the sidewalk in a residen-
tial area. According to neighbors gathered at the scene,
the woman had been wandering around the neighbor-
hood since early morning. No one recognized her and
several people had tried to approach her to offer help or
give directions. She would not or could not give her name
or address; much of her speech was garbled and hard to
understand. She was not carrying a purse or identifica-
tion. She finally collapsed and appeared unconscious, so
they called emergency services.
The woman was taken to the emergency room. She
was perspiring profusely, was found to have a fever of
103.2°F and was grossly dehydrated. Intravenous ther-
apy was started to replenish fluids and electrolytes. ACLINICALVIGNETTE: DELIRIUM
cooling blanket was applied to lower her temperature,
and she was monitored closely over the next several
hours. As the woman began to regain consciousness,
she was confused and could not provide any useful in-
formation about herself. Her speech remained garbled
and confused. Several times she attempted to climb out
of the bed and remove her intravenous tube, so re-
straints were used to prevent injury and to allow treat-
ment to continue.
By the end of the second day in the hospital, she
could accurately give her name, address, and some of
the circumstances surrounding the incident. She re-
membered she had been gardening in her back yard in
the sun and felt very hot. She remembered thinking she
should go back in the house to get a cold drink and rest.
That was the last thing she remembered.