Foundations Of Cognitive Science


Dementia is a clinical state characterized by loss of function in multiple cognitive domains. The most commonly used criteria for diagnoses of dementia is the DSM-IV (Diagnostic and Statistical Manual for Mental Disorders, American Psychiatric Association). Diagnostic features include :

  • memory impairment and at least one of the following: aphasia, apraxia, agnosia, disturbances in executive functioning.
  • In addition, the cognitive impairments must be severe enough to cause impairment in social and occupational functioning.
  • Importantly, the decline must represent a decline from a previously higher level of functioning.
  • Finally, the diagnosis of dementia should NOT be made if the cognitive deficits occur exclusively during the course of a delirium.

There are many different types of dementia (approximately 70 to 80). Some of the major disorders causing dementia are:

  1. Degenerative diseases (e.g., Alzheimer's Disease, Pick's Disease)
  2. Vascular Dementia (e.g., Multi-infarct Dementia)
  3. Anoxic Dementia (e.g., Cardiac Arrest)
  4. Traumatic Dementia (e.g., Dementia pugilistica [boxer's dementia])
  5. Infectious Dementia (e.g., Creutzfeldt-Jakob Disease)
  6. Toxic Dementia (e.g., Alcoholic Dementia)

In 1994, 7.9 % of all Canadians 65 years and older meet the criteria for the clinical diagnoses of dementia (Canadian Study on Health and Aging, 1994). The Canadian Alzheimer Society web page reported that in January, 2009 approximately 500,000 Canadians were living with Alzheimer's disease or a related dementia, and that 71,000 of these individuals were younger than 65 years of age. By 2014, it is possible that 250,000 new dementia diagnoses will be made in Canada, and that within a generation (25 years) the number of afflicted Canadians could reach between 1 and 1.3 million.

  • References:
    1. American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.
    2. Canadian study of health and aging: Study methods and prevalence of dementia. (1994). Canadian Medical Association Journal, 150(6).

    (Revised March 2010)

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