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Types of Dementia

Alzheimer’s Disease is the most common form of dementia, accounting for 60 to 80 percent of dementia cases.  Alzheimer’s causes problems with memory, thought processes and behavior.  Symptoms usually develop slowly and get worse over time.  For many, a decline in non-memory aspects of cognition, such as word finding, vision/spatial issues, and impaired reasoning or judgement, may signal the very early stages.

Vascular Dementia was previously known as multi-infarct or post-stroke dementia and is less common as a sole cause of dementia than Alzheimer’s.  It is the second most common cause of dementia.  Vascular dementia occurs from blood vessel blockage or damage in the brain.  The location, number and size of the vessel disease and blockages determines how the individual’s thinking and physical functioning are affected.  Vascular Dementia can occur over time as “silent” strokes pile up.

Symptoms include impaired judgement, inability to make decisions, plan or organize as opposed to the memory loss often associated with the initial symptoms of Alzheimer’s.

Dementia with Lewy bodies is the third most common cause of dementia after Alzheimer’s disease and vascular dementia, accounting for 10 to 25 percent of cases.  Lewy bodies are also found in other brain disorders, such as Parkinson’s disease dementia.  Many people with Parkinson’s eventually develop problems with thinking and reasoning and many people with Dementia with Lewy bodies experience movement symptoms such as hunched posture, rigid muscles, a shuffling walk and trouble initiating movement.

Symptoms of Dementia with Lewy bodies include:

  • Changes in thinking and reasoning
  • Confusion and alertness that varies significantly from one time of day to another or from one day to the next
  • Parkinson’s symptoms, such as a hunched posture, balance problems and rigid muscles
  • Visual hallucinations
  • Delusions
  • Trouble interpreting visual information
  • Acting out dreams, sometimes violently
  • Memory loss that may be significant but less prominent than in Alzheimer’s

Frontotemporal Dementia affects the frontal and temporal lobes.  Changes in the frontal lobe are associated with behavioral symptoms, while changes in the temporal lobe lead to language and emotional disorders.

Symptoms are often misunderstood.  Family members and friends may think that a person is misbehaving, leading to anger and conflict.  It is important to understand that the individual cannot control their behaviors nor do they have any insight into the extent of their disease.

Mixed Dementia:  In the most common form of mixed dementia, the abnormal protein deposits associated with Alzheimer’s disease coexist with blood vessel problems linked to vascular dementia.  Alzheimer’s brain changes also coexist with Lewy bodies.  In some cases, a person may have brain changes linked to all three conditions.