Chapter 19

Delirium, Dementia, and Amnestic and Other Cognitive Disorders

(Neurocognitive Disorders)

Scientific Course of Neurological Disorders

• Developments in treatment and cures for neurological disorders have been very slow

• Understanding concussions and persistent postconcussive syndrome

• DSM-5 changes to terminology and classification of disorders

• Technological advances contributing to advances in neuropsychology

Changing Views of Brain Function and Dysfunction

• How the brain mediates behaviors– Major methodologies used in this research:

• Examination of brain function through lesion generation or brain stimulation in animals

• Studies of patients with localized brain damage

• Shifting emphasis from points to pathways– Uniting localization and pathways— Luria

• Key concepts in neuropsychology: Contralateral control, cerebral dominance, equipotentiality versus pluripotentiality, neurotransmitters

Description of the Disorder: Neuropathological Considerations

• Outcomes of brain damage influenced by age, sociocultural status, personality, and most importantly by type of brain damage

• Accurate assessment of brain damage requires use of appropriate scan (CT versus MRI)

• Type of brain disorder– Degenerative versus static, reversible versus

irreversible, slow versus rapid progression, morbidity

Description of the Disorder: Sources of Brain Damage

• Head trauma– Aftereffects may be temporary (most concussions) or

permanent (closed or open head injury) – Nature of the symptoms varies on an individual basis;

some make full recovery, but others are limited – Trauma patients may be at greater risk for developing

Alzheimer’s disease • Brain tumors– Symptoms dependent on tumor classification (malignant

versus nonmalignant, glioma versus meningioma)– Symptoms dependent on brain region affected

Description of the Disorder: Sources of Brain Damage cont.

• Brain malformations and early-life brain damage– There is a difference between destruction of

function already acquired and destruction of the brain mechanisms needed to acquire that function before it has been developed

– Concept of plasticity– Pre- and perinatal influences on brain

development

Description of the Disorder: Sources of Brain Damage cont.

• Diseases of the circulatory system– Cerebral arteriosclerosis– Vascular dementia– Aneurysm

• Degenerative and demyelinating diseases– Common factors: attack the CNS, slowly progressive and

incurable, stem from unknown defect in physiology– Alzheimer’s disease

• Lewy body dementia and Parkinson’s disease

– Huntington’s chorea– Multiple sclerosis– Creutzfeldt-Jakob disease

Description of the Disorder: Sources of Brain Damage cont.

• Alcoholism– Development of alcoholism– Wernicke-Korsakoff syndrome

• Toxic, infectious, and metabolic illnesses– Carbon monoxide poisoning– Phenylketonuria (PKU)– Tay-Sachs disease– Bacterial infections (e.g., encephalitis, meningitis,

neurosyphylis)– Viruses

Description of the Disorder: Sources of Brain Damage cont.

• Epilepsy– Characterized by seizures (sudden, abrupt

alteration of brain function produced by an excessive, disorganized discharge of neurons)

– Generalized seizures• Grand mal and petit mal seizures

– Partial seizures– Higher probability of significant intellectual deficit

when the disorder involves generalized seizures and appears early in life

Some Common Syndromes

• The communicative disorders– Fluent (Wernicke’s) aphasia

• Speech is fluent, but generally incomprehensible; tendency to substitute incorrect words for correct ones (verbal paraphasia)

• Primary disturbance involves profoundly impaired auditory comprehension

• Lesion is generally in the superior gyrus of the left temporal lobe

– Nonfluent (Broca’s) aphasia• Comprehension is better, but speech is very difficulty and limited.• Lesion is in the lower, posterior portion of the left frontal lobe

– Lost abilities: alexia (reading), agraphia (writing), and acalculia (difficulties with numbers)

Some Common Syndromes cont.

• Disorders of perception and motility – Agnosias: Difficulty recognizing some class of external

objects • Classified with regard to modality and verbal or nonverbal

content

– Neglect: Most dramatic is vision, where the patient may neglect the entire right or left side of the visual world

– Apraxias: Basic deficit involves impairment of purposive movement occurring in the absence of paralysis, weakness, or unsteadiness

Some Common Syndromes cont.

• Dementia (Major and Mild Neurocognitive Disorders)– Several types but all involve usually slowly

progressive deterioration of intellectual function• Deterioration is frequently patterned, typically

beginning with loss of memory, and other abilities deteriorating at later stages of the illness • Different from intellectual disability because it involves

deterioration from a previous higher intellectual level

Some Common Syndromes cont.

• Most common dementia is Alzheimer’s disease– New method to specifically diagnose Alzheimer’s

disease in a living patient; previously could only be diagnosed postmortem by examining plaques in the brain

– Generally begins with signs of impairment of memory for recent events, followed by deficits in judgment, visual-spatial skills, and language • Language difficulty does not resemble aphasia, but involves

word-finding difficulties and progressive inability to produce extended and comprehensible narrative speech

Some Common Syndromes cont.

• Vascular dementia– Associated with hypertension and a series of

strokes, with the end result being substantial deterioration (not uniform, but stepwise and patchy deterioration)

• Frontotemporal dementia– Characterized by executive dysfunction; have

greater impairment of executive function but relatively better memory and visuoconstructional abilities than Alzheimer’s patients

Some Common Syndromes cont.

• Amnesia– Memory loss is clearly the most outstanding

deficit (i.e., dementia patients are often amnesic, but their memory disturbance is embedded in significant generalized impairment of intellectual and communicative abilities)

– Brain structures particularly important for memory: limbic system (hippocampus) and certain brainstem structures (mammillary bodies and dorsomedial nucleus of the thalamus)

Some Common Syndromes

• Amnesia– Anterograde versus retrograde• Anterograde amnesia is the inability to form new

memories from the time of the onset of the illness, whereas retrograde amnesia is the inability to recall events that took place before the onset of the illness• Individuals with Korsakoff’s syndrome demonstrate

severe retrograde amnesia

Alternative Descriptive Systems

• Not all clinicians or researchers have adopted the neuropsychologically oriented syndrome approach

• Alternative method is a dimensional approach in which patients are measured on a variety of neuropsychologically relevant dimensions, such as intellectual function, language ability, and memory – Involves profiling the patient along several continuous

dimensions and relating that profile to underlying brain mechanisms

Epidemiology

• Depends on the disorder• MS: the further from the equator, the greater

the prevalence• Head injuries occur more frequently in males– Also in individuals of lower SES

• Huntington’s disease: marker for the gene located on chromosome 4; prevalence: 5 to 7/100,000

• Alzheimer’s disease and general health habits

Course and Prognosis

• Vary across disorders• Acceleration stages (rate of progression of the

disorder)– Steady state, slow, moderate, and rapid

• Developmental stage (age of onset): perinatal period, early childhood, late childhood and adolescence, early adulthood, middle age, and old age

Course and Prognosis cont.

• Strokes– Onset in middle age; initially rapid progression that slows.– Recovery is common

• Malignant brain tumors– Those that appear in middle age tend to progress rapidly unless

removed • Progressive dementias

– Generally appear during middle or old age and accelerate moderately or slowly

• Head trauma– May occur at any age– Rehabilitation aids recovery

Familial and Genetic Patterns

• Huntington’s disease and Down syndrome are genetic disorders

• Suspected genetic component to Alzheimer’s, though not well understood

• Cardiovascular health has associated familial factors, as does alcoholism

• Tay-Sachs disease occurs almost exclusively in Eastern European Jews