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Parkinson's Disease Dementia and Lewy-Body Dementia

Any information regarding treatments in this page are provided as a reference only, and are not intended as treatment advice.

Lewy-Bodies are abnormal aggregates of protein that develop inside neurons in the brain and can be identified under the microscope. When they are found in an area of the brain known as the substantia nigra they are associated with Parkinson's Disease, and when they are found in the neocortex they are associated with Lewy-Body Dementia. There is thus an overlap in the symptoms and in the nature of these two conditions, and in many cases of these illnesses the characteristic microscopic brain changes of Alzheimer's Disease can also be found [ref].

The symptoms of dementia that can occur in Parkinson's Disease Dementia and Lewy-Body Dementia are similar to the impairments characteristic of Alzheimer's Disease, and include memory impairment, aphasia, apraxia, agnosia, and executive function deficits. The diagnosis of Parkinson's Disease Dementia is made when these symptoms occur at least one year after Parkinson's Disease has developed [ref], which happens in up to 40% of cases of Parkinson's Disease [ref].

In Lewy-Body Dementia, the cognitive impairments described above are the first symptoms to develop, and they begin gradually and insidiously and progress with time, much the same as in Alzheimer's Disease. In addition, the core symptoms that characterize Lewy-Body Dementia are [ref]:

  • Fluctuations in cognitive functions from time to time with episodes of marked variations in alertness and attention
  • Episodes of visual hallucinations that are typically well-formed and detailed
  • Spontaneous features of Parkinsonism

Other features that commonly occur in Lewy-Body Dementia include [ref]: REM sleep disruption; prominent extrapyramidal symptoms in response to low doses of antipsychotics; repeated falls and syncope; episodes of unexplained loss of consciousness; autonomic dysfunction (eg. orthostatic hypotension, urinary incontinence); hallucinations in other modalities; delusions; and depression.

In terms of treatment, Cholinesterase Inhibitors tend to be effective in delaying the progression of the cognitive deficits in Lewy-Body Dementia [ref] and Parkinson's Disease Dementia [ref], and in alleviating the symptoms of psychosis in Lewy-Body Dementia [ref]. If further measures are required to control any psychotic symptoms, low dose Atypical Antipsychotics such as Quetiapine, Aripiprazole or Clozapine can be tried [ref]. An SSRI or Venlafaxine can be used to treat depressive symptoms in these conditions, though there is little empirical evidence to support this.


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Mild Cognitive Impairment (MCI)

Frontotemporal Dementia (FTD)