Parkinson’s disease dementia occurs with Parkinson’s disease in about 30% of patients.
Some of these patients when autopsied have the senile plaques and neurofibrillary tangles typical for Alzheimers disease, others show Lewy bodies at autopsy. But many do not show either and that’s why it is thought that the degenerative brain changes of Parkinson disease itself can be enough reason to develop a dementia.
Here are some interesting statistics: In the younger age group of less than 50 years about 100 people among 100,000 will develop Parkinsons disease, but at an age of more than 80 years this jumps to 1100 per 100,000 population. Between the age of 50 and 60 about 10% of these patients will develop Parkinson’s disease dementia, at an age of more than 80 years can reach 70%.
Scientists know that any degenerative or other pathological change within the nerve pathways between the frontal lobes of the brain and the cognitive brain (parietal lobes of the brain) as well as in the switching centers of the extrapyramidal system in the lower parts of the brain and the brainstem will lead to cognitive disturbances and ultimately Parkinson’s disease dementia.
From a pathological view point it has been shown that there is a more or less linear relationship between the amount of plaques and tangles in the cortex and the associated severity of the degree of dementia.
The degenerative process of Parkinson’s disease that is associated with dopamine deficiency in the nerve cells is also thought to be a reason for the development of dementia in these patients.
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