-Dementia is a general term that describes a group of symptoms-such as loss of memory, judgment, language, complex motor skills, and other intellectual function-caused by the permanent damage or death of the brain’s nerve cells, or neurons.
-One or more of several diseases, including Alzheimer’s disease, can cause dementia.
-Alzheimer’s disease is the most common cause of dementia in persons over the age of 65. It represents about 60 percent of all dementias.
-The other most common causes of dementia are vascular dementia, caused by stroke or blockage of blood supply, and dementia with Lewy bodies. Other types include alcohol dementia, caused by sustained use of alcohol; trauma dementia, caused by head injury; and a rare form of dementia, frontotemporal dementia.
-The clinical symptoms and the progression of dementia vary, depending on the type of disease causing it, and the location and number of damaged brain cells. Some types progress slowly over years, while others may result in sudden loss of intellectual function.
-Each type of dementia is characterized by different pathologic, or structural, changes in the brain, such as an accumulation of abnormal plaques and tangles in individuals with Alzheimer’s disease, and abnormal tau protein in individuals with frontotemporal dementia.