Cognitive Impairment: The Issue


Dementia is a term applied to a group of signs and symptoms seen in a variety of diseases affecting the brain. For the most part it is a chronic or progressive disease of older people resulting in impairment of higher brain functions such as memory, thinking, orientation, comprehension, calculation, learning capacity, language, judgment, and executive function to a degree sufficient to affect daily activities. Consciousness is not clouded (as in delirium); however the impairments of cognitive functioning are commonly accompanied, and occasionally preceded, by deterioration in emotional control, social behaviour, or motivation.

People with early dementia may exhibit some of the following symptoms:

  • Problems remembering recent events;
  • Difficulty performing familiar tasks or learning new ones;
  • Changes in mood, personality and behaviour;
  • Impaired judgment and reasoning; and,
  • Difficulty finding words, finishing thoughts or following directions.

Although the chance of developing dementia increases with age, dementia is not a normal part of aging. Overall 8% of people over the age of 65 have dementia, but this varies from 1- 2% of the population at age 65 to about 35% of the population over the age of 85.

There are a number of different forms of dementia, the most common are described below:

Alzheimer’s Disease

A progressive disease of the brain featuring memory loss and at least one of the following cognitive disturbances:

  1. Language disturbances (aphasia);
  2. An impaired ability to carry out motor activities despite intact motor function (apraxia);
  3. A failure to recognize or identify objects despite intact sensory function (agnosia); and
  4. Disturbance in executive functions such as planning, organizing, sequencing, and abstracting.

Vascular Dementia

A dementia that is a result of brain cell death that occurs when blood circulation is cut off to parts of the brain. This may be the result of a single stroke or multiple strokes, or more diffusely as the result of small vessel disease.

Dementia with Lewy Bodies

This disease often has features of both Alzheimer’s disease and Parkinson’s disease. Microscopic `Lewy bodies’ are found in affected parts of the brain. Common symptoms include visual hallucinations, fluctuations in alertness and attention, and a tendency to fall.

Frontal Lobe Dementia

A dementia that primarily affects the frontal lobes of the brain and results in early impairment in the control of personal, social and interpersonal conduct: loss of insight; emotional level blunting; and language deficits.

Alcohol Related Dementia

Dementia caused when damage to brain cells occurs from excessive consumption of alcohol.

Other Dementias

These include dementias associated with Creutzfeldt-Jakob disease, Huntington’s disease, Parkinson’s disease, brain injury, HIV/AIDS, Down Syndrome, developmental disabilities, and mental illnesses.

Mixed Dementias

People may
show features of more than one type of dementia. For example, many people, especially the very old, appear to have a mix of Alzheimer’s disease and Vascular Dementia.

Alzheimer’s disease is the most common form of dementia—approximately 60% of all people who have dementia have Alzheimer’s disease. After that, estimates vary with Vascular Dementia accounting for approximately 5-10% and Dementia with Lewy Bodies accounting for about 5% of all dementias. Mixed dementias account for approximately 20 – 30% of all dementias.

A related condition is called Mild Cognitive Impairment. Mild cognitive impairment or MCI is frequently described as a “transition phase” of cognitive decline that can occur in some individuals between the cognitive changes associated with normal aging and cognitive losses identified in the early stages of various dementias. The cognitive losses are evidenced by either self and/or informant (e.g. family, caregiver) report along with deficits on objective cognitive tasks, and/or evidence of decline over time detected by neuropsychological testing. Ten to fifteen percent of people each year, who are diagnosed with MCI, will progress to dementia when followed over a five-year period.

Because dementia is a progressive degenerative condition, people who have dementia tend to move through clinical stages as they progress through their disease. These stages have been defined based on tests for mental competency. As dementia progresses, significant change to the person’s personality and mood can occur.

Health clinicians generally refer to three commonly accepted stages of dementia: Mild, Moderate, and Severe.
These three stages are described below.


The person who has mild dementia is still able to function somewhat independently; however, memory loss and thinking impairment is present. Caregivers will experience stress because of the functional changes in the person with dementia


The person who is in a moderate stage of dementia will experience further decreases in memory, thinking, and concentration skills. This decline in functioning results in an increased need for supervision and assistance. In this stage there can also be changes in behaviour and a potential for `wandering’. The caregiver is at risk for stress, depression, general health deterioration, and loss of productivity at work.


The person who is in the severe stage of dementia experiences a considerable loss of memory, language skills, and living skills. Due to these losses, the person cannot be left unsupervised and requires total assistance in all activities of daily living. There is a total dependence on the caregiver(s) who are at risk for all of the impacts identified above. Severe dementias include the end of life care for the person with dementia

People living with dementia and their caregivers often refer to the significant transitions associated with the disease rather than the clinical stages described above. The transitions are typically key changes for the person and their caregiver as the disease causes deteriorations in function (cognitive and physical) that trigger significant life and care planning decisions and a decrease in quality of life. Typical transition points are the receipt of the diagnosis of dementia, the need to make decisions that are linked to a loss of independence (e.g. loss of ability to drive), changes in living environment (e.g. a need to move in with a family member), and decisions about residential and end of life care. These points of transition are often the times when additional support from health care and other support services is required by the people living with dementia and their caregivers.

Excerpt From The British Columbia Dementia Service Framework ; September 2007.


The British Columbia Dementia Service Framework

Dementia Policy Lens (2009)