Parkinson’s disease dementia is a type of dementia that occurs in a person with Parkinson’s disease. It is more common with older age and with more years of having Parkinson’s disease. Earlier on in the course of Parkinson’s disease, a person may have mild cognitive impairment rather than dementia. The disease is progressive and shortens lifespan.
The symptoms of Parkinson’s disease dementia may include problems with memory, visuospatial function, and executive function. There can be a slowness in thinking and problems with concentration, and losing one’s train of thought in conversation. Judgment may change. Psychiatric symptoms such as depression, apathy, anxiety, delusions, and hallucinations may occur. The symptoms are like those experienced in dementia with Lewy bodies, except that in Parkinson’s disease dementia the person already has a firmly established diagnosis of Parkinsons’s disease for years before the dementia occurs. This is in contrast to dementia with Lewy bodies, where the parkinsonism occurs around the same time as the dementia. Under the microscope, the pathologic changes in the brains of people with Parkinson’s disease dementia and dementia with Lewy bodies are the same, but the clinical conditions present differently because the disease begins in different areas, before becoming more widespread to cause the overlapping symptoms.
There is no cure for Parkinson’s disease dementia. Many medications that help the physical symptoms in Parkinson’s disease can contribute to the cognitive worsening in Parkinson’s disease dementia. A comprehensive evaluation can help determine if a person with Parkinson’s disease has mild cognitive impairment or Parkinson’s disease dementia, and can identify medications or medical conditions to target to help improve cognitive function. Physical therapy, occupational therapy, speech-language therapy, and/or swallow therapy may also be recommended.