Dementia is “an acquired syndrome that causes the progressive loss of intellectual abilities, such as memory, language (aphasia), the person’s ability to use tools (apraxia), to recognize objects (agnosia) and to plan and think in abstract terms (loss of executive function). Dementia is present if at least memory and one additional intellectual ability are impaired and if the impairment is severe enough to interfere with social or occupational functioning” (American Psychiatric Association, 1994).
The most common type of progressive dementia is Alzheimer’s disease. It is characterized by gradual onset and continuing, progressive decline in cognitive function. Build up of beta-amyloid protein fragments and abnormal tangles of tau protein inside certain brain cells are characteristic pathologic changes. Ten percent of people age 65 and older and 50% of those over 85 are thought to have dementia of the Alzheimer’s or similar type (Flood, M. & Buckwalter, K.C. (2009).
Another form of progressive dementia is vascular or multi-infarct dementia. The onset of vascular dementias is more abrupt and symptoms include focal neurological symptoms (Mahoney, et al., 2000).