The Cognitive Disorders

The Cognitive Disorders

Chapter Overview/Summary

The DSM-IV recognizes various cognitive disorders, including delirium, dementia, and amnesticdisorder. Typically, these disorders result from transient or permanent damage to the brain. Chronicneuropsychological disorders involve permanent loss of neural cells.The primary causes of brain tissue destruction are many and varied; common ones includecertain infectious diseases (such as the HIV-1 virus), brain tumors, physical trauma (injuries andalcohol), degenerative processes (as in Alzheimer’s disease), and cerebrovascular arteriosclerosis, oftenmanifested as vascular dementia. There is no simple relationship between the extent of brain damageand degree of impaired functioning. Some people who have severe damage develop no severe

symptoms, while others with slight damage have extreme reactions. Although such inconsistencies arenot completely understood, it appears that an individual’s premorbid personality and life situation areimportant in determining his or her reactions to brain damage. The APOE-4 genetic allele may also be

important.

Delirium is a fluctuating condition common among the elderly. It involves a state of awarenessbetween wakefulness and stupor or coma. It is treated with neuroleptic medications and also withbenzodiazepines.Dementia involves a loss of function and of previously acquired skills. It has a slowonset and often a deteriorating course. The most common cause of dementia is Alzheimer’s disease. Age is amajor risk factor for Alzheimer’s disease as well as other forms of dementia, such as vascular dementia.Genes play a major role in creating susceptibility and risk for Alzheimer’s disease. Genetic mutations ofthe APP, presenilin 1 and presenilin 2 genes are implicated in early onset AD. The APOE-4 allele of theAPOE gene is also a risk factor for AD. Interestingly, substantial numbers of MZ twins are discordantfor AD suggesting that genetic susceptibility interacts with environmental factors. Environmental factorsinclude diet, exposure to metals such as aluminum, and experiencing head traumaThe characteristic neuropathology of Alzheimer’s disease involves cell loss, senile plaques and

neurofibrillary tangles. Plaques contain a sticky protein called beta amyloid. Neurofibrillary tanglescontain abnormal tau protein. Alzheimer’s disease causes a destruction of cells that make acetylcholine,a neurotransmitter important for memory. Drug treatments for AD include cholinesterase inhibitors suchas donepezil (Aricept). These drugs help stop ACh being broken down and so make more of it availableto the brain.Amnestic disorders involve severe memory loss. The most common cause of amnestic disordersis chronic alcohol abuse. Head injuries can cause amnesia as well as other cognitive impairments.Retrograde amnesia is the ability to recall events before the accident. Anterograde amnesia is theinability to remember things since the accident.

Any comprehensive treatment approach for cognitive disorders should also involve caregivers,who are often under a great deal of stress and have difficulties coping. They may benefit frommedications as well as from support groups.

Detailed Lecture Outline

I. Brain Impairment in Adults

A. Diagnostic Issues

1. DSM-IV-TR presents the diagnostic coding in different and somewhat confusingways

2. For cognitive disorders, both cognitive problem and medical cause are listed onAxis I; medical condition listed again on Axis III

3. Brain changes due to substances are simply placed on Axis I

B. Clinical Signs of Brain Damage

1. For most part, cell bodies and neural pathways do not regenerate

2. Impairment may involve acquired and customary skills or capacity for realistic

self-appraisal (anosognosia)

3. Impairment depends on:

a. Nature, location, and extent of neural damage

b. Premorbid competence and personality of the individual

c. Individual’s life situation

d. Amount of time since the first appearance of the condition

C. Diffuse versus Focal Damage

1. Attention is often impaired by mild to moderate diffuse damage, such as might beexpected with moderate oxygen deprivation or the ingestion of toxic substances

2. Mild cognitive impairment can also be detected in those who have had only low-levelexposure to organic solvents and other neurotoxins

3. Focal brain lesions are circumscribed areas of abnormal change in the brain with anumber of possible consequences

4. Relationships between brain location and behavior can never be considered

universally true, however:

a. Damage to frontal areas can result in one of two patterns

(1) Behavioral inertia, passivity, apathy, and perserverative thought

(2) Impulsiveness and distractibility

b. Damage to right parietal lobe may produce impairment of visual-motor

coordination

c. Damage to left parietal area may impair language, including reading andwriting, as well as arithmetical abilities

d. Damage to certain structures within temporal lobes disrupts memorystorage; extensive bilateral temporal lobe damage can result in no newmemories being able to be stored; damage to other structures withintemporal lobe can lead to disturbances of eating, sexuality, and theemotions

e. Occipital damage produces a variety of visual impairments and visualassociation deficits

D. The Neuropsychology/Psychopathology Interaction

1. Most people with a neuropsychological disorder do not have psychopathologicalsymptoms

2. Psychopathological symptoms not always predictable

II. Delirium

A. Clinical Presentation

1. Delirium is an acute confused state with a sudden onset and a fluctuating state ofawareness

2. Commonly find: cognitive changes such as impaired information-processing,

hallucinations, delusions, abnormal psychomotor activity (wild thrashing),disturbances of the sleep cycle

3. Mayresult from head injury, infection, drug intoxication, drug withdrawal, drugtoxicity

B. Treatment and Outcome

1. Medical emergency – must identify and treat underlying cause

2. Most cases are reversible

3. Treatment involves medications (neuroleptics or benzodiazepines for drug

withdrawal), environmental manipulations such as orienting techniques(calendars, staff prompting, night lights), and family support

III. Dementia

A. Dementia

1. Decline from a previous level of functioning; onset typically gradual

2. Memory for recent events affected in early stage; with time, increasingly markeddeficits in abstract thinking, acquisition of new knowledge or skills, visuospatialcomprehension, motor control, problem solving, and judgment

3. Often accompanied by impairment in emotional control and moral/ethical

Sensibilities

4. Dementia may be progressive or static

5. Occasionally reversible if underlying cause can be treated

6. Strokes, degenerative disease (Alzheimer’s, Huntington’s, and Parkinson’s),

infectious diseases (syphilis, meningitis, AIDS), intracranial tumors andabscesses, dietary deficiencies (B vitamins), head injury, anoxia, and toxicsubstances can produce the condition

B. Alzheimer’s Disease (AD)

1. The clinical picture in Alzheimer’s disease

a. Diagnosis based on clinical assessment but can only be confirmed afterdeath

b. Usually begins after age 45

c. Gradual and slow mental deterioration is seen with multiple cognitivedeficits

d. First sign may be withdrawal from active engagement with life followedby more self-centered and child-like thoughts and activities including apreoccupation with functions of eating, digestion and excretion; assymptoms become more severe may see impaired memory for recentevents, “empty” speech, messiness, impaired judgment, agitation, andperiods of confusion

e. Delusions (paranoid and jealous) and a combative pattern occur in somepatients

f. Death usually comes from lowered resistance to opportunistic infections

2. Prevalence of Alzheimer’s disease

a. Problem is underestimated

b. 1% to 2% of population between 65 -74; about 25% of those over 85

c. With increasing life span problem grows in magnitude

d. Women have a slightly higher risk

e. Lower rates in Japan, Nigeria, and India suggesting role of high fat, highcholesteroldiet

f. High levels of an amino acid homocystine increases risk for AD and heartdisease

3. Genetic and environmental aspects of Alzheimer’s disease

a. Early-onset Alzheimer’s disease

(1) Progression very rapid

(2) Have identified three rare genetic mutations that can cause this(about 5% of cases)

(a) Mutated APP gene on chromosome 21

(b) Mutated PS1 (presenilin 1) gene on chromosome 14

b. Late-onset Alzheimer’s disease

(1) APOE (apolopoprotein) gene on chromosome 19

(a) Three alleles identified

(b) APOE-E4 significantly enhances risk for late-onset AD

(d) APOE-E4 can be detected by blood test

(e) Only 55% of those with two APOE-E4 alleles haddeveloped AD by age 80

(2) Substantial numbers of MZ twins are discordant for AD

(3) Genetic susceptibility thought to interact with environmentalfactors

(4) Environmental factors include diet, exposure to metals such asaluminum, and experiencing head trauma

(5) Exposure to ibuprofen may be protective

c. Neuropathology

(1) Senile plaques

(a) Contain a sticky substance called beta amyloid

(b) Believed that an accumulation of this substance causes

plaques

(2) Neurofibrillary tangles

(a) Webs of abnormal filaments within a nerve cell made up of

a protein called tau

(b) Tau may be caused by accumulation of beta amyloid

(3) Granulovacuolars

(a) Small holes caused by cell degeneration

(b) Leads to reduction in acetylcholine activity

4. Treatments and outcomes in Alzheimer’s disease

a. No effective treatment exists

b. Behavioral techniques attempt to control wandering, incontinence,

inappropriate sexual behavior, and poor self-care behaviors

c. Medications such as tacrine (Cognex) and donepezil (Aricept) that inhibitthe production of acetylcholinesterase thereby increasing the availabilityof acetylcholine

d. Newest medication is Namenda that appears to regulate glutamate

e. Despite setbacks, continuing to work on developing vaccines

f. Prevention is needed

5. Treating caregivers

a. Challenging management problems as well as “social death” of the patientand their own “anticipatory grief”

b. Caregivers are at high risk for developing depression

c. Providing caregivers with counseling and support has proven effective

C. Dementia from HIV-1 Infection

1. Snider (1983) documented that the presence of the HIV-1 virus could itself resultin the destruction of brain cells

2. May lead to the emergence of psychotic phenomena

3. Virus causes generalized atrophy, edema, inflammation, and patches of

demyelination

4. Damage may occur throughout brain but seems to be localized in subcorticalregions, notably the white matter, the tissue surrounding the ventricles, and deepergray matter structures such as the basal ganglia and thalamus

5. Between 30 and 60 percent of untreated patients with HIV/AIS will develop

AIDS-related dementia; with current antiviral treatment, the rate reduces to 20%

D. Vascular Dementia (multi-infarct dementia)

1. A similar clinical picture to Alzheimer’s exists; although a more varied earlypicture

2. Series of circumscribed cerebral infarcts cumulatively destroy neurons overexpanding brain regions

3. Tends to occur after 50; more common in men

4. Accounts for only about 19% of all dementia cases; patients are more vulnerableto sudden death from stroke or cardiovascular event

5. Accompanying mood disorders more common than in AD

6. “Mixed” diagnosed when patient has both vascular and AD

7. Cerebral arteriosclerosis can be medically managed to some extent

IV. Amnestic Syndrome

A. Central feature is strikingly disturbed memory or amnesia

1. Immediate recall and memory for remote events usually preserved

2. Short-term memory typically very impaired

3. Confabulation common

B. Overall cognitive functioning may remain relatively intact

C. Root cause brain damage typically from chronic alcohol use with its associateddeficiency in vitamin B1

D. Other causes include: head trauma, stroke, surgery in the temporal lobe, hypoxia, braininfections

E. Depending on cause, may abate wholly or partially

V. Disorders Involving Head Injury

A. Traumatic Brain Injury

1. Occurs frequently affecting more than 2 million people each year in the U.S.

2. Most common cause is motor vehicle accidents followed by falls, violent assaults,and sports injuries

3. Men aged 15-24 are at greatest risk

4. Clinical Picture

a. Three types of injury are distinguished

(1) Closed head

(2) Penetrating

(3) Skull fracture

b. Immediate acute reactions such as unconsciousness and disruption ofcirculatory, metabolic, and neurotransmitter regulation

c. Retrograde and anterograde amnesia are commonly seen

d. Person typically passes through stupor and confusion on the way torecovering clear consciousness

e. Coma may occur

f. Presence of the APOE-E4 allele is a risk factor for increased problemsafter a brain injury

g. Phineas Gage

A. Treatments and Outcomes

1. Prompt medical care is required

2. The majority suffering mild concussion improve quickly

3. 24% of TBI cases develop post-traumatic epilepsy, presumably because of thegrowth of scar tissue in the brain

4. In a minority of cases, dramatic personality change occurs

5. Children with severe traumatic brain injury are more likely to be adverselyaffected the younger they are

6. Severe injury cases have a poor prognosis

7. Recent evidence suggests that patients with TBI may benefit from treatment withdonepezil, and acetylcholinesterase inhibitor

VI. Unresolved Issues: Can Dietary Supplements Enhance Brain Functioning?

A. Gingko biloba (derived from the leaves of the gingko tree) widely used to improvememory

1. Oken and colleagues (1998) found that AD patients who received gingko

performed better cognitively than patients who took placebo; results similar towhen patients took donepezil

2. More recent study (2000) failed to find any effects

3. Gold and colleagues (2002) support Oken’s study

B. Other cognitive enhancers?

1. Phosphatatidylserine (PS) has been recommended for memory but findings are inconsistent and minimal

2. Results looking at choline, found in foods containing lethicin, seem to beequally Insignificant

Key Terms

AIDS-related dementia

amnestic syndrome

amyloid plaques

anterograde amnesia

APOE-4 allele

delirium

dementia

early-onset Alzheimer’s disease

functional mental disorders

late-onset Alzheimer’s disease

neurofibrillary tangles

organic mental disorders

retrograde amnesia

traumatic brain injury (TBI)

vascular dementia (VAD)