Dementia is a clinical syndrome of loss or decline in memory and other cognitive abilities.
It is caused by various diseases and conditions that result in damaged brain cells.

Alzheimer’s disease is a type of dementia and the most common cause of dementia.

To be classified as dementia, the syndrome must meet the following criteria:
   1. It must include decline in memory and in at least one of the following cognitive
      abilities:

	Ability to generate coherent speech and understand spoken or written language;
	Ability to recognize or identify objects, assuming intact sensory function;
	Ability to perform motor activities, assuming intact motor abilities, sensory function and comprehension of the required task;
	Ability to think abstractly, make sound judgments and carry out complex tasks.

    2. The decline in cognitive abilities must be severe enough to interfere with daily life.      

Alzheimer’s Disease -
Most common type of dementia; accounts for 60 to 80 percent of cases. Difficulty remembering names and recent events is often an early clinical symptom; later symptoms include impaired judgment, disorientation, confusion, behavior changes and trouble speaking, swallowing and walking. Hallmark abnormalities are deposits of the protein fragment beta-amyloid (plaques) and twisted strands of the protein tau (tangles).

Vascular Dementia – also known as multi-infarct or post stroke dementia or vascular cognitive impairment. Considered the second most common type of dementia. Impairment is caused by decreased blood flow to parts of the brain, often due to a series of small strokes that block arteries. Symptoms often overlap with those of Alzheimer’s, although memory may not be as seriously effected.

Mixed Dementia - Characterized by the presence of the hallmark abnormalities of Alzheimer’s and another type of dementia, most commonly vascular dementia, but also other types, such as dementia with Lewy bodies, frontal-temporal dementia, alcohol-related dementia and normal pressure hydrocephalus.

Dementia with Lewy Bodies - Pattern of decline may be similar to Alzheimer’s, including problems with memory, judgment and behavior changes. Alertness and severity of cognitive symptoms may fluctuate daily. Visual hallucinations, muscle rigidity and tremors are common. Hallmarks include Lewy bodies (abnormal deposits of the protein alpha-synuclein) that form inside nerve cells in the brain.

Parkinson’s Disease - Many people who have Parkinson’s disease develop dementia in the later stages of the disease.

Frontal-Temporal Dementia - Involves damage to brain cells, especially in the front and side regions of the brain. Typical symptoms include changes in personality and behavior and difficulty with language. No distinguishing microscopic abnormality is linked to all cases. Pick’s disease, characterized by “Pick’s bodies,” is one type of frontal-temporal dementia.

Creutzfeldt-Jacob Dementia - Rapidly fatal disorder that impairs memory and coordination and causes behavior changes. It is believed to be caused by consumption of products from cattle infected by “mad cow disease.” Caused by the misfolding of prion protein throughout the brain.

Normal pressure Hydrocephalus - Caused by the buildup of fluid in the brain. Symptoms include difficulty walking, memory loss and inability to control urine. Can sometimes be corrected with surgical installation of a shunt in the brain to drain excess fluid.