screening for dementia; screening for cognitive impairment; screening for Alzheimer's disease

Indications

• no obvious benefits or harms of screening for dememtia in primary care

* also see cognitive assessment

Diagnostic criteria

• clinical diagnosis of dementia requires cognitive impairment that interferes with activities of daily living
• also see diagnostic criteria for dementia

Laboratory

• CSF tau increases 10 years before onset of dementia
• CSF Abeta42 decreases 18 years before onset of dementia

Clinical significance

• cognitive decline begins 6 years prior to onset of dementia
• intact olfaction & intact global cognition together predict a no progression to dementia
• race & apoE4 genotype may influence odor identification screening & global cognitive screening & their association with risk of dementia

Procedure

• simple cognitive assessment tools
  • executive function assessment
    • clock drawing test
    • time & change test
  • mental status examination
    • Folstein mini-mental status examination (MMSE)
      • modified mini-mental status examination (MMMSE)#
      • of no benefit in assessing risk of MCI progressing to dementia
    • MiniCog*
    • Montreal Cognitive Assessment (MoCA)*
      • MoCA-B useful for illiterate or low-education elderly
      • precedence over screening for depression
    • others
  • visuospatial function assessment (language-independent)
    • visual association test improves predictive value of the MMSE score for development of dementia
    • clock drawing test (also falls in this category)
• somewhat more complex cognitive assessment*
  • consisting of:
    • mini mental status examination
    • neuropsychological testing
      • episodic/recall ability
      • verbal fluency
      • visuospatial skills
  • detects 18% of early-stage Alzheimer's disease developing within 3 years
  • 100% predictive value for development of early Alzheimer's disease
• screening for depression
• QuoCo tool (cognitive chart)
• cognitive screening by telephone 10-CS
  • 10-point cognitive screen
    • 1 point each for correct year, month, & date
    • 1 point for each of 3 named objects that are remembered several minutes later
    • points for naming animals
      • 4 points for >= 15 animals for fewer animals
  • instructions for administering & scoring the 10-CS are available free of charge in the online supplement of

* free tools validated in primary care populations

# MMSE may be better than MoCA for cognitive screening in African American patients

# MoCA is better than MMSE for detecting MCI in the elderly, particularly in the oldest old population

Radiology

• PET scan with Pittsburg compound B for amyloid*
• brain MRI for hippocampal atrophy* & white matter lesions*
  • shrinkage of hippocampal volume 8 years before onset of dementia

* presence of 2 of 3 predicts dementia

* hippocampal atrophy associated with 5-fold risk

* white matter lesions associated with ~3-fold risk

Management

• insufficient evidence to recommend for or against screening
• screening best postponed until effective therapy available
• consider screening for all older adults, despite lack of effective treatment
  • actually 2-5% of cases are due to reversible causes
  • early warnings could avoid problems with
  • driving
  • financial mismanagement
  • social isolation
• screening of nursing home residents for dementia does not reduce emergency department transfers
• a healthy diet, adequate sleep, & exercise should be part of recommendations for every patient, regardless of cognitive complaints

More general terms

• screening

Additional terms

• cognitive assessment