Chapter Chapter 1 / Emergency Management: Evaluation of the Critically Ill or Injured Child 44

Cognitive
8 Disorders

The cognitive disorders are delirium, dementia, and toxicity, although a great number of commonly used
amnestic disorders. Table 8-1 lists the Diagnostic and medications, prescribed and over the counter, can
Statistical Manual of Mental Disorders, 4th edition, produce delirium. Other conditions predisposing to
classification of cognitive disorders. delirium include old age, fractures, and preexisting
dementia.

 DELIRIUM
Epidemiology
Delirium is a reversible state of global cortical dys- The exact prevalence in the general population is
function characterized by alterations in attention and unknown. Delirium occurs in 10% to 15% of general
cognition and produced by a definable precipitant. medical patients older than age 65 and is frequently
Delirium is categorized by its etiology (see Table seen postsurgically and in intensive care units. Delir-
8-1) as due to general medical conditions, substance- ium is equally common in males and females.
related, or multifactorial in origin.
Clinical Manifestations
Etiology
History and Mental Status Examination
Delirium is a syndrome with many causes. Most fre- History is critical in the diagnosis of delirium, par-
quently, delirium is the result of a general medical ticularly in regard to the time course of development
condition; substance intoxication and withdrawal of the delirium and to the prior existence of demen-
also are common causes. Structural central nervous tia or other psychiatric illness. Key features of delir-
system lesions can also lead to delirium. Table 8-2 ium are
lists common general medical and substance-related
causes of delirium. Delirium is often multifactorial 1. Disturbance of consciousness, especially attention
and may be produced by a combination of minor ill- and level of arousal;
nesses and minor metabolic derangements (e.g., mild 2. Alterations in cognition, especially memory, ori-
anemia, mild hyponatremia, mild hypoxia, and entation, language, and perception;
urinary tract infection, especially in an elderly 3. Development over a period of hours to days; and
person). Common medical causes of delirium 4. Presence of medical or substance-related
include metabolic abnormalities such as hypona- precipitants.
tremia, hypoxia, hypercapnia, hypoglycemia, and In addition, sleep-wake cycle disturbances and psy-
hypercalcemia. Infectious illnesses, especially urinary chomotor agitation may occur. Delirium is often dif-
tract infections, pneumonia, and meningitis, are often ficult to separate from dementia, in part because
implicated. The common substance-induced causes dementia is a risk factor for delirium (and thus they
of delirium are alcohol or benzodiazepine with- frequently co-occur) and in part because there is
drawal and benzodiazepine and anticholinergic drug a great deal of symptom overlap, as outlined in
 Chapter 8 / Cognitive Disorders 45

 TABLE 8-1
Cognitive Disorders
Delirium Dementia Amnestic
General medical Alzheimers type General medical
Substance-related Vascular origin Substance-related
Multifactorial HIV-related
Head trauma-related
\Parkinsons-related
Huntingtons-related
Picks-related
Creutzfeldt-Jakobrelated
General medical origin
Substance-related
Multifactorial

 TABLE 8-2 deficits are generally more stable. In both conditions,

there may be nocturnal worsening of symptoms with
Common Causes of Delirium increased agitation and confusion (sundowning).
General Medical Substance-Related The diagnosis of delirium is complicated by the
fact that there are no definitive tests for delirium. The
Infectious Intoxication
workup for delirium includes a thorough history and
Urinary tract infections Alcohol
Meningitis Hallucinogens mental status examination, a physical examination,
Pneumonia Opioids and laboratory tests targeted at identifying general
Sepsis Marijuana medical and substance-related causes. These should
Metabolic Stimulants include urinalysis, complete chemistry panel, com-
Hyponatremia Sedatives plete blood count, and oxygen saturation. Additional
Hepatic encephalopathy Withdrawal workup might entail chest X ray, arterial blood
Hypoxia Alcohol gas (ABG), neuroimaging, or electroencephalogram
Hypercarbia Benzodiazepines (EEG). EEG may reveal nonspecific diffuse slowing.
Hypoglycemia Barbiturates The presence of a delirium is associated with a 1-year
Fluid imbalance Medication-induced
mortality rate of 40% to 50%.
Uremia Anesthetics
Hypercalcemia Anticholinergics Differential Diagnosis
Postsurgical Meperidine
Hyper/hypothyroidism Antibiotics Delirium should be differentiated from dementia
Ictal/postictal Toxins (although both can be present at the same time), psy-
Head trauma Carbon monoxide chotic or manic disorganization, and status complex
Miscellaneous Organophosphates partial epilepsy.
Fat emboli syndrome
Thiamine deficiency
Anemia Management
The treatment of delirium involves keeping the
patient safe from harm while addressing the delir-
Table 8-3. Key differentiating factors are the time ium. In the case of delirium due to a general medical
course of development of the mental status change illness, the underlying illness must be treated; in sub-
(especially if the patient did not have a prior demen- stance-related delirium, treatment involves removing
tia) and the presence of a likely precipitant for the the offending drug (either drugs of abuse or medica-
mental status change. Individuals with delirium may tions) or the appropriate replacement and tapering
also display periods of complete lucidity interspersed of a cross-reacting drug to minimize withdrawal.
with periods of confusion, whereas in dementia, the Delirium in the elderly is frequently multifactorial
46 Blueprints Psychiatry

 TABLE 8-3
Delirium versus Dementia
Delirium Dementia
Onset Hours to days Weeks to years
Course/duration Fluctuates within a day. May last hours Stable within a day. May be permanent,
to weeks* reversible, or progressive over weeks
to years
Attention Impaired May be impaired
Cognition Impaired memory, orientation, language Impaired memory, orientation, language,
executive function
Perception Hallucinations, delusions, misinterpretations Hallucinations, delusions
Sleep/wake Disturbed, may have complete day/night Disturbed, may have no pattern
reversal
Mood/emotion Labile affect Labile affect; mood disturbances
Sundowning Frequent Frequent
Identified precipitant Likely precipitant is present Identifiable precipitant not required
* DSM-IV does not specify a limit for the duration for delirum; clinical experience suggests resolution within days to weeks, in most cases.

and requires correction of a multitude of medical Etiology

conditions.
Generally, the etiology of dementia is brain neuronal
In addition to addressing the cause of a delirium,
loss that may be due to neuronal degeneration or to
oral, intramuscular, or intravenous haloperidol is of
cell death secondary to trauma, infarction, hypoxia,
great use in treating agitation. Low doses of short-
infection, or hydrocephalus. Table 8-1 lists the major
acting benzodiazepines can be used sparingly. Pro-
discrete illnesses known to produce dementia. In
viding the patient with a brightly lighted room with
addition, there are a large number of general medical,
orienting cues such as names, clocks, and calendars is
substance-related, and multifactorial causes of
also useful.
dementia.

KEY POINTS Epidemiology

1. Delirium is a disorder of attention and cognition. The prevalence of dementia of all types is about 2%
2. It has an abrupt onset and a variable course. to 4% after age 65, increasing with age to a preva-
3. It has an identifiable precipitant. lence of about 20% after age 85. Specific epidemio-
4. 1-year mortality rate is greater than 40%. logic factors relating to disease-specific causes of
dementia are listed in Table 8-4.

 DEMENTIA Clinical Manifestations

History and Mental Status Examination
Dementia is characterized by the presence of
Dementia is diagnosed in the presence of multiple
memory impairment in the presence of other cogni-
cognitive defects not better explained by another
tive defects. Dementia is categorized according to its
diagnosis. The presence of memory loss is required;
etiology (see Table 8-1). It can arise as a result of a
in addition, one or more cognitive defects in the cat-
specific disease, for example Alzheimers disease or
egories of aphasia, apraxia, agnosia, and disturbance
HIV infection; a general medical condition; or a
in executive function must be present. Table 8-3
substance-related condition; or it can have multiple
compares characteristics of dementia to those of
etiologies. The definitive cause may not be
delirium. Dementia often develops insidiously over
determined until autopsy.
the course of weeks to years (although it may be
 Chapter 8 / Cognitive Disorders 47

 TABLE 8-4
Specific Diseases Associated with Dementia
Disease Description
Alzheimers Most common cause of dementia, accounts for greater than 50% of all cases. Risk factors are
familial, Down syndrome, prior head trauma, increasing age. Clinically, it is a diagnosis of exclusion.
Post-mortem pathology reveals cortical atrophy, neurofibrillary tangles, amyloid plaques,
granulovacuolar degeneration, loss of basal forebrain cholinergic nuclei. Course is progressive,
death occurs 810 years after onset.
Vascular Second most common cause of dementia. Risk factors are cardiovascular and cerebrovascular
disease. Neuroimaging reveals multiple areas of neuronal damage. Neurological exam reveals
focal findings. Course can be rapid onset or more slowly progressive. Deficits are not reversible,
but progress can be halted with appropriate treatment of vascular disease.
HIV Limited to those cases caused by direct action of HIV on the brain; associated illnesses, such as
meningitis, lymphoma, toxoplasmosis producing dementia are categorized under dementia due
to general medical conditions. Primarily affects white matter and cortex.
Head trauma Most common among young males. Extent of dementia is determined by degree of brain
damage. Deficits are stable unless there is repeated head trauma.
Parkinsons Occurs in 2060% of individuals with Parkinsons disease. The most likely pathological finding on
autopsy is Lewy body disease. Bradyphrenia (slowed thinking) is common. Some individuals also
have pathology at autopsy consistent with Alzheimers dementia.
Huntingtons Risk factors are familial, autosomal dominant on chromosome 4. Onset commonly in mid 30s.
Emotional lability is prominent. Caudate atrophy is present on autopsy.
Picks Onset at age 5060. Frontal and temporal atrophy are prominent on neuroimaging. The dementia
responds poorly to psychotropic medicine.
Creutzfeldt-Jakob Ten percent of cases are familial. Onset age 4060. Prion is thought to be agent of transmission.
Clinical triad of dementia, myoclonus, and abnormal EEG. Rapidly progressive. Spongiform
encephalopathy is present at autopsy.

abrupt after head trauma or vascular insult). Indi- A critical component of differential diagnosis in
viduals with dementia usually have a stable presen- dementia is to distinguish pseudodementia associ-
tation over brief periods of time, although they may ated with depression. Although there are many
also have nocturnal worsening of symptoms (sun- precise criteria for separating the two disorders, neu-
downing). Memory impairment is often greatest for ropsychological testing may be needed to make an
short-term memory. Recall of names is frequently accurate diagnosis. In pseudodementia, mood symp-
impaired, as is recognition of familiar objects. Exec- toms are prominent and patients may complain
utive functions of organization and planning may be extensively of memory impairment. They character-
lost. Paranoia, hallucinations, and delusions are often istically give I dont know answers to mental status
present. Eventually, individuals with dementia may examination queries but may answer correctly if
become mute, incontinent, and bedridden. pressed. Memory is intact with rehearsal in pseudo-
dementia, but not in dementia.
Differential Diagnosis
Dementia should be differentiated from delirium. In
Management
addition, dementia should be differentiated from
those developmental disorders (such as mental Dementia from reversible, or treatable, causes should
retardation) with impaired cognition. Individuals be managed first by treating the underlying cause of
with major depression and psychosis can appear the dementia; rehabilitation may be required for
demented; they warrant a diagnosis of dementia only residual deficits. Reversible (or partially reversible)
if their cognitive deficits cannot be fully attributed causes of dementia include normal pressure hydro-
to the primary psychiatric illness. cephalus; neurosyphilis; HIV infection; and thiamine,
48 Blueprints Psychiatry

folate, vitamin B12, and niacin deficiencies. Vascular confusion may resolve, leaving a residual amnestic
dementias may not be reversible, but their progress disorder called Korsakoffs psychosis (alcohol-
can be halted in some cases. Nonreversible demen- induced persistent amnestic disorder).
tias are usually managed by placing the patient in a
safe environment and by medications targeted at
Epidemiology
associated symptoms. Tacrine, an acetylcholinesterase
inhibitor, has some efficacy in treating memory loss Individuals affected by a general medical condition
in dementia of the Alzheimers type. High-potency or alcoholism are at risk for amnestic disorders.
antipsychotics (in low doses) are used when agita-
tion, paranoia, and hallucinations are present. Low-
Clinical Manifestations
dose benzodiazepines and trazodone are often used
for anxiety, agitation, or insomnia. History and Mental Status Examination
Amnestic disorders present as deficits in memory,
either in the inability to recall previously learned
KEY POINTS information or the inability to retain new informa-
1. Dementia is a disorder of memory impairment tion. The cognitive defect must be limited to memory
coupled with other cognitive defects. alone; if additional cognitive defects are present, a
2. It has a gradual onset and progressive course. diagnosis of dementia or delirium should be consid-
3. It may be caused by a variety of illnesses. ered. In addition to defect in memory, there must be
4. Dementia predisposes to delirium. an identifiable cause for the amnestic disorder (i.e.,
the presence of a general medical condition or sub-
stance use).

 AMNESTIC DISORDERS Differential Diagnosis

Delirium and dementia are the major differential
Amnestic disorders are isolated disturbances of diagnostic considerations. Amnestic disorders are dis-
memory without impairment of other cognitive tinguished from dissociative disorders on the basis of
functions. They may be due to a general medical con- etiology. By definition, amnestic disorders are due to
dition or substance related. a general medical condition or substance.

Etiology Management
Amnestic disorders are caused by general medical The general medical condition is treated whenever
conditions or substance use. Common general possible to prevent further neurologic damage; in the
medical conditions include head trauma, hypoxia, case of a substance-related amnestic disorder, avoid-
herpes simplex encephalitis, and posterior cerebral ing reexposure to the substance responsible for the
artery infarction. Amnestic disorders often are asso- amnestic disorder is critical. Pharmacotherapy may
ciated with damage of the mammillary bodies, be directed at treating associated anxiety or mood
fornix, and hippocampus. Bilateral damage to these difficulties. Patients should be placed in a safe, struc-
structures produces the most severe deficits. Amnes- tured environment with frequent memory cues.
tic disorders due to substance-related causes may be
due to substance abuse, prescribed or over-the-
counter medications, or accidental exposure to KEY POINTS
toxins. Alcohol abuse is a leading cause of substance-
1. Amnestic disorders are disorders in memory
related amnestic disorder. Persistent alcohol use may
alone.
lead to thiamine deficiency and induce Wernicke-
2. They are caused by identifiable precipitants.
Korsakoffs syndrome. If properly treated, the acute
3. Amnestic disorders are reversible in some cases.
symptoms of ataxia, abnormal eye movements, and