Dementia

Dementia is a syndrome of premature neuronal death in focal brain regions. More than 50 illnesses may cause dementia. It affects 1% of the population by age 60, and this prevalence doubles every 5 years to reach 30–50% by age 85. Common findings include aphasia (language disorder of speech, comprehension, naming, reading, and writing), apraxia (inability to perform previously learned tasks such as combing hair or “saluting the flag”), and agnosia (impaired recognition or comprehension of specific auditory, visual, and tactile stimuli).

Differential Diagnosis

• Alzheimer's disease is the most common cause of dementia
• Lewy body dementia
• Multi-infarct dementia
• Parkinson's disease
• Alcohol/drugs
• Vitamin deficiency (B₁₂, thiamine)
• CNS infections
  –HIV encephalitis
  –Meningitis
  –Herpes encephalitis
  –Creutzfeldt-Jacob disease
  –Cerebral abscess
  –Neurosyphilis
• Depression (pseudodementia)
• Head trauma
• Pick's disease
• Chronic subdural hematoma
• Huntington's disease
• Chronic hydrocephalus
• Paraneoplastic encephalitis
• Hypothyroidism
• Cerebral vasculitis
• Systemic lupus erythematosus (lupus cerebritis)
• Wilson's disease
• Chronic hypoglycemia or hypocalcemia
• Uremic encephalopathy
• Dialysis dementia
• Multiple sclerosis
• Hydrocephalus
• Postanoxic dementia

Workup and Diagnosis

• Important to distinguish dementia from delirium (acute metabolically induced state of fluctuating consciousness) and depression
• A complete history and physical are essential to rule out underlying medical, neurologic, or psychiatric illnesses that may mimic symptoms of dementia
  –Mini-mental status exam
  –Medication history should be elicited to identify drugs that may contribute to cognitive changes (e.g., analgesics, sedatives, anticholinergics, antihypertensives)
  • Labs may include CBC, electrolytes, calcium, BUN/creatinine, liver function tests, glucose, thyroid function tests, vitamin B₁₂ and folate, screening for inflammatory/infectious causes, and toxicology screen
  • CT without contrast to rule out structural lesions (e.g., infarct, malignancy, hydrocephalus, extracerebral fluid collection)
  • EEG is not routinely used; however, it may identify toxic/metabolic disorders or Creutzfeldt-Jakob disease
  • Genetic testing may be indicated if family history suggests Alzheimer's disease (especially early-onset)
    –Mutations of chromosomes 1, 14, 21
    –Increased frequency of apolipoprotein ∊ 4 allele
    • CSF analysis may be useful in some cases
    • HIV and syphilis (RPR) testing if known risk factors

    Treatment

    • Treat reversible causes (e.g., hypothyroidism, vitamin deficiency, cerebral vasculitis, neurosyphilis, HIV)
    • Manage nonreversible etiologies, including genetic risks, health care planning, and help groups (e.g., Alzheimer's Association)
    • Alzheimer's disease: Anticholinesterases (e.g., tacrine, donepezil) may improve cognitive function; selegiline and α
    • -tocopherol may delay progression
    • Vascular dementia: Treat risk factors (e.g., discontinue tobacco use, lower blood pressure and lipids)
      –Note that lost cognitive function will not return despite treatment
  • Parkinson's disease: Dopamine and dopamine agonists; anticholinergics improve function but do not affect progression of disease; selegiline may slow disease progression

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

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Copyright Details: In a Page: Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X

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