Cognitive Impairment

Lisa N. Richey, Matthew E. Peters, M.D.


  • Cognitive impairment refers to deficits in neurocognitive domains.
    • Deficits can be defined as a difference from baseline, difference from age and education matched controls, or difference from the level of other neurocognitive domains in an individual (e.g., a deficit in complex attention with all other domains intact).
    • Cognitive impairment can be classified into three severity levels: Mild (difficulty with instrumental activities of daily living), Moderate (difficulty with basic activities of daily living), and Severe (fully dependent on caregivers).
      • Subclinical cognitive changes not evident on formal testing, termed “subjective cognitive complaints”, have some value in predicting future dementia[1] and appear to be associated with comorbid depressive symptoms in older adults[2].
    • Cognitive impairment can present with or without behavioral disturbance.
    • The neurocognitive deficits cannot solely occur within an episode of delirium.
  • The neurocognitive domains are as follows[3]:
    • Complex attention (sustained attention, divided attention, selective attention, processing speed)
      • Example deficits: difficulty with multiple stimuli, easily distracted, unable to perform mental calculations
    • Executive function (planning, decision making, working memory, responding to feedback/error correction, overriding habits/inhibition, mental flexibility)
      • Example deficits: unable to do complex projects, extra effort required to organize, difficulty switching between tasks, problems with impulse control, lacks motivation
    • Learning and memory (short-term memory, long-term memory, episodic memory, semantic memory)
      • Example deficits: repeats self in conversation, requires frequent reminders, difficulty recalling events that occurred in recent and/or distant past
    • Language (expressive language and receptive language)
      • Example deficits: impaired word finding (e.g., using general phrases ("that thing on your foot") rather than the name of an object ("shoe"), trouble with names of family members, grammatical errors
    • Perceptual-motor (visual perception, visuo-constructional, perceptual-motor, praxis)
      • Example deficits: trouble with previous familiar activities, trouble navigating familiar environments, trouble with spatial tasks
    • Social cognition (recognition of emotions, theory of mind)
      • Example deficits: behavior out of acceptable social range, insensitivity to social standards, makes decisions without regard to safety
  • When talking about global declines in cognition, two phrases are commonly used: dementia and delirium. Defined simply,
    • Dementia: global cognitive decline in the presence of a clear sensorium
    • Delirium: global cognitive decline in the setting of a clouded sensorium

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Last updated: May 13, 2022