Alzheimer’s disease: Most common type of dementia; accounts for an estimated 60–80 percent of cases. Difficulty remembering names and recent events is often an early clinical symptom; apathy and depression are also often early symptoms. Later symptoms include impaired judgment, disorientation, confusion, behavior changes and difficulty 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 affected.

Mixed dementia: Characterized by the hallmark abnormalities of Alzheimer’s and another type of dementia — most commonly vascular dementia, but also other types, such as demen- tia with Lewy bodies. Recent studies suggest that mixed dementia is more common than previously thought.

Dementia with Lewy bodies: Pattern of decline may be similar to Alzheimer’s, including problems with memory and judgment as well as 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 (a disorder that usually involves movement problems) also develop dementia in the later stages of the disease. The hallmark abnormality is Lewy bodies (abnormal deposits of the protein alpha- synuclein) that form inside nerve cells in the brain.

Frontotemporal 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 frontotemporal dementia.

Creutzfeldt-Jakob disease: Rapidly fatal disorder that impairs memory and coordination and causes behavior changes. Variant Creutzfeldt-Jakob disease is believed to be caused by consumption of products from cattle affected 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 urination. Can sometimes be corrected with surgical installation of a shunt in the brain to drain excess fluid.

Information obtained from the 2010 Alzheimer’s Disease Facts and Figures. http://www.alz.org/documents_custom/report_alzfactsfigures2010.pdf. Post by Kate Valdovinos.