Alzheimer’s disease

  • Incidence: Alzheimer’s is the most common from of dementia, affecting an estimated 5.4 million Americans. It’s the sixth-leading cause of death in the U.S.
  • Description: Alzheimer’s is a fatal, progressive brain disorder that damages and eventually destroys brain cells. Its hallmarks in the brain are plaques of a protein fragment called beta amyloid, twisted microscopic strands of the tau protein, and loss of the connections that transmit information between cells.
  • Symptoms: Early signs include difficulty remembering recent conversations, names or events; apathy; and depression. Later symptoms include impaired communication, poor judgment, disorientation, confusion, behavior changes, and difficulty speaking, swallowing and walking.

Vascular dementia

  • Incidence: This condition is the second most common cause of dementia. It accounts for about 10 percent of dementia cases.
  • Description: Vascular dementia is caused by damage from strokes. The location, number and size of the brain injury determines the effect on thinking and physical functioning.
  • Symptoms: Impaired judgment and ability to make decisions, and impaired planning or organizing skills are likely the initial symptoms, as opposed to the memory loss associated with Alzheimer’s.

Dementia with Lewy bodies

  • Incidences: This is thought to be the third most common cause of dementia. It accounts for 10 to 25 percent of cases.
  • Description: Abnormal aggregates of protein that develop inside nerve cells, called Lewy bodies, build up in the brain. Lewy bodies are also found in other brain disorders, including Alzheimer’s and Parkinson’s disease dementia.
  • Symptoms: The condition may cause changes in alertness and attention, hallucinations, problems with movement and posture, muscle stiffness and confusion. It’s hard to diagnose because Parkinson’s and Alzheimer’s cause similar symptoms.

Parkinson's disease dementia

  • Incidence: An estimated 1 million Americans have Parkinson’s disease, and 50 to 80 percent of them eventually experience Parkinson’s disease dementia.
  • Description: Parkinson’s is a chronic, progressive movement disorder that involves the malfunction and death of neurons in the brain. As damage spreads, dementia may arise.
  • Symptoms: Parkinson’s disease dementia is marked by a decline in memory, thinking and reasoning. The average time from onset of Parkinson’s to developing dementia is about 10 years.

Sources: Alzheimer’s Association and the Dementia Society of America