As the emergency physician on call, you are asked to see Mrs. H., a 75 year old woman who was found confused and attempting to make her front door key fit an apartment door downstairs from her own. On examination, it takes several attempts to gain her attention to answer any questions. Her answers are rambling and disorganized, and her speech is at times incoherent. She is drowsy and falls asleep at times during the interview. When awake, she appears to be talking about things that are in the room with her, and is unable to describe where she is, who she is, or where she lives. The exam does not reveal specific abnormalities relating to other body systems, and there is no sign of injury or falling. There are no localizing or lateralizing signs on neurological examination. She is unable to cooperate with a Mini-Mental State exam.

Q: Is this patient delirious, demented, or both?

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Q: What additional information would be helpful in the initial evaluation of this patient?

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Differential Diagnosis of Cognitive Disorders in the Elderly

Common cognitive disorders in older people include delirium, dementia, depressive "pseudodementia", and benign senescent forgetfulness.

Delirium

• An acute disorder usually associated with medical illness, medications, etc.
• More slowly progressive cognitive impairment
• Includes most dementias, benign senescent forgetfulness
• Impaired cognition associated with affective disorders or psychoses
• Key features of delirium:
  • acute onset
  • fluctuating course
  • disorganized thinking
  • altered level of consciousness
  • inattention, distractibility
  • underlying medical cause

• Prevalence 
  • 10-15% of older medical patients at admission
  • An additional 5-30% develop delirium in hospital
  • 1/3-2/3 of cases are unrecognized or misdiagnosed

• Significance
  • Delirium is often secondary to other serious, treatable conditions
  • Associated with
    • ‚ short-term mortality
    • ‚ length of hospital stay
    • ‚ risk of institutionalization, functional decline
  • Persistent cognitive impairment in many cases
  • unclear whether delirium predisposes to dementia, or whether it merely unmasks the presence of previously unrecognized cognitive impairment

• Improving Recognition of Delirium
  • Perform brief cognitive testing in elderly patients at risk, e.g., at the time of admission
    • attention (serial 7's, days of week backwards)
    • short term recall (3 objects at 2 minutes)
  • Interview caregivers, family members
    • ask about confusion, inappropriate behaviors, hallucinations, etc.
  • Consider in evaluation of any confused patient
  • Identify potential precipitating factors
    • medications, dehydration, urinary retention, fecal impaction, acute illnesses, infections, hypoxia, drug/alcohol withdrawal

Dementia

• Key features 
  • Cognitive deficits in multiple domains, including memory
  • Progressive deterioration (months/years)
  • Cognitive impairment interferes with activities of daily living
  • No disorder of alertness

• Presentation
  • Patients rarely seek medical care for symptoms
  • lack of insight common
  • Usually brought in by family, friends
  • Delay in diagnosis common
  • caregivers may gradually take on more care for the patient, "masking" the true magnitude of the deficits

   

• Dementia Syndromes

  I. Alzheimer's disease

  •  A clinical diagnosis of exclusion
    • no acceptable"gold standard" lab test for diagnosis before deat
  • Typically presents with gradual impairment in memory, functional status, and other areas of cognition over a 1-2 year period
    • impairment in recent memory often an early sign

II. Vascular dementia

• Diagnosis: based on recognition of a sudden onset of cognitive impairment in association with a stroke, a step-wise deteriorating course, neuroimaging evidence of previous strokes, focal neurologic exam findings, and/or presence of risk factors for stroke

III. Rapidly progressive dementia 

• This category includes "treatable" dementias, such as toxic or metabolic disturbances (medications, chronic alcoholism, severe hypothyroidism), as well as depressive pseudodementias
• Other rapidly progressive dementias are usually associated with neurologic signs and symptoms (e.g., motor disturbances, headaches, seizures)
  • Creutzfeld-Jakob disease (cerebellar ataxia and motor deficits)
  • Intracranial tumors
  • Cryptococcal meningitis (rarely occurs in non-immunocompromised patients; symptoms rarely present for >6 months)
  • Chronic subdural hematoma (unusual for this to occur in absence of a clear history of head trauma)
  • Normal pressure hydrocephalus (dementia, ataxia, urinary incontinence; may benefit from trials of removal of spinal fluid prior to shunting procedure)

IV. Dementia with extrapyramidal features

• Associated with Parkinson's disease (Lewy Body dementia)
• Extrapyramidal signs: rigidity, bradykinesia, tremor, gait and balance problems
• Diagnosis is clinical; not based on lab testing or imaging studies
• Hallucinations, delusions, falls commonly occur
• Neuroleptic medications may worsen symptoms

V. Frontal lobe dementia

• Pick's Disease is prototype
• Prominent early changes in affect, behavior
• Personality changes, lack of insight, disinhibition

Dementia: Clinical Evaluation

• History 
  • Obtain from family or close contact
  • Determine date of onset, rate of progression
  • Evaluate effect of cognitive impairment on patient's ability to function
• Further evaluation by the physician focuses on
  • Differentiating dementia from delirium, depression, and benign senescent forgetfulness
  • Ruling out "reversible" causes:
    • Drugs/delirium (mainly drugs with central nervous system activity)
    • Emotional illness (depressive pseudodementia)
    • Metabolic/endocrine disorders (e.g., hypothyroidism, hypercalcemia)
    • Eye/ear/environment (sensory impairment may superficially resemble dementia)
    • Nutritional (e.g., vitamin B-12 or severe B-1 deficiencies)
    • Tumors/trauma
    • Infection (including HIV, cryptococcal meningitis)
    • Alcoholism/anemia/atherosclerosis

Benign senescent forgetfulness

• Clinical features:
  • Mild age-related memory impairment (e.g., names, dates)
  • Not rapidly progressive
  • No increased risk of institutionalization
  • No significant interference with activities of daily living

• Management approach:
  • Cautious reassurance
  • Repeat cognitive function testing annually or as needed

Depressive pseudodementia

• May be difficult to distinguish from dementia
• Some older depressed patients don't report depressed mood
• Pseudodementia: Approach
  • Maintain high index of suspicion in cognitively impaired patients
  • Look for vegetative symptoms (appetite/sleep changes, psychomotor retardation/agitation, anhedonia)
  • Therapeutic trial of antidepressant for questionable cases

Features Distinguishing Dementia and Depressive Pseudodementia:

	Dementia	Pseudodementia
Precise onset	Unusual	Usual
Duration	Long	Short
Complaints of cognitive loss	Variable	Usual
Hx of psych illness	Uncommon	Common
"Don't know" answers	Uncommon	Common
Affect	Labile, blunted	Depressed

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University of Washington, Division of Gerontology and Geriatric Medicine

Copyright 1999, 2000 David A. Gruenewald, M.D. and Kayla I. Brodkin, M.D. All rights reserved.