Cognitive impairment in older adults has a variety of possible causes, including medication side effects, metabolic and/or endocrine derangements, delirium due to intercurrent illness, depression, and dementia, with Alzheimer’s dementia being most common. Some causes, like medication side effects and depression, can be reversed with treatment. Others, such as Alzheimer’s disease, cannot be reversed, but symptoms can be treated for a period of time and families can be prepared for predictable changes. (from the National Institute on Aging, 2016.) 1 According to the Alzheimer Society of Canada(2016) 2  564 000 Canadians are living with dementia and this number is expected to rise to 937 000 by 2030. The current annual cost to Canadians to care for those with dementia is 10.4 billion dollars. The prevalence of older adults with MCI is difficult to estimate because of differences in the definition of MCI and methods used in studies; estimates range widely, from 3% to 42% in adults age 65 years and older. Approximately 40% to 50% of older adults report subjective memory symptoms. The rate of progression of MCI to dementia is uncertain (Lin, 2013) 3 Delirium  involves the acute onset and/or fluctuating onset of a change in thinking and level of consciousness and is triggered by an acute medical event or medication. Up to a third of inpatients 70 years old and above experience delirium, and the rate is much higher for those in intensive care or undergoing surgery. (Collier, 2012) 4

Some Important Definitions:
• Dementia is defined by the DSM-V, and involves a decline in cognition involving one or more cognitive domains. The deficits must represent a decline from previous level of function and be severe enough to interfere with daily function and independence.
• Mild Cognitive Impairment refers to a decline in cognition involving 1 or more domain with no decline in functional ability or independence.
• Subjective Cognitive Impairment is when a patient perceives they have a deficit in 1 or more cognitive domains but you cannot identify any deficit on cognitive testing and there has been no functional decline.
• Delirium involves the acute onset and/or fluctuating onset of a change in thinking and level of consciousness. It is triggered by an acute medical event or medication.


Additional Resources:

  • Frailty eLearning Module - “Cognition
  • Frailty eLearning Module - “Delirium


  1. National Institute on Aging. (2014) Assessing Cognitive Impairment in Older Adults: A quick guide for primary care physicians.
  2. Alzheimer Society Canada (2016) Dementia numbers in Canada. Accessed from
  3. Lin JS, O'Connor E, Rossom RC, Perdue LA, Ekstrom E. (2013) Screening for cognitive impairment in older adults: a systematic review for the U.S. Preventive Services Task Force. Ann Intern Med. 159(9):601-12.
  4. Collier, R. (2012) Hospital induced delirium hits hard. CMAJ, 184(1):23-4.
  5. Recognizing Delirium, Depression and Dementia chart accessed from