"Parkinson’s disease Dementia (PDD), a clinical diagnosis related to [Lewy Body Dementia] that can occur in people with Parkinson’s disease. PDD may affect memory, social judgment, language, or reasoning. Autopsy studies show that people with PDD often have amyloid plaques and tau tangles similar to those found in people with Alzheimer's disease, though it is not understood what these similarities mean.
A majority of people with Parkinson’s disease develop Dementia, but the time from the onset of movement symptoms to the onset of Dementia symptoms varies greatly from person to person. Risk factors for developing PDD include the onset of Parkinson’s-related movement symptoms followed by mild cognitive impairment and REM sleep behavior disorder, which involves having frequent nightmares and visual hallucinations."
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