Dementia is a term that describes a collection of symptoms that include decreased intellectual functioning that interferes with normal life functions and is usually used to describe people who have two or more major life functions impaired or lost such as memory, language, perception, judgment or reasoning; they may lose emotional and behavioral control, develop personality changes and have problem solving abilities reduced or lost.
There are different classification schemes for dementias roughly based (and with overlap) on observed problems; some frequently used are cortical (memory, language, thinking, social) , subcortical (emotions, movement, memory), progressive (cognitive abilities worsen over time), primary (results from a specific disease such as Alzheimer's disease and secondary (occurs because of disease or injury).
TYPES OF DEMENTIA
Alzheimer's disease (AD): is the most common cause of dementia in people over age 65 with cause possibly related to amyloid plaques and neurofibrillary tangles; almost all brain functions, including memory, movement, language, judgment, behavior, and abstract thinking, are eventually affected.
Vascular dementia: is the second most common cause of dementia caused by brain damage from cerebrovascular or cardiovascular problems (strokes) or other problems that inhibit vascular function; symptoms similar to AD but personality and emotions effected only late in the disease.
Lewy body dementia: is common and progressive where cells in the brain's cortex die and other contain abnormal structures (Lewy bodies); symptoms overlap with Alzheimer's disease but also include hallucinations, shuffling gait, and flexed posture with symptoms that may vary daily.
Frontotemporal dementia: is dementia linked to degeneration of nerve cells in the frontal and temporal brain lobes and some evidence for a genetic factor (many have a family history of the disease); symptoms in patients (usually ages 40 – 65) have judgment