The recognition of cognitive impairment in patients with Parkinson's disease has major implications for their management. Although prospective studies of patients with Parkinson's disease show that the illness usually follows a course extending over many years, dementia brings with it important changes in the care a patient will require and in their life expectancy. These needs will progressively increase and will place an increasing burden upon the patient's immediate family and carers. The timing of wills and other legal procedures may be affected.
The most important step in the recognition of dementia in Parkinson's disease is to suspect its presence. There are many features of Parkinson's disease that tend to obscure the appearance of new clinical features of the disease. The typical blank facial expression seen in Parkinson's disease may obscure a decline in intellectual activity, slowness in movement may conceal intellectual slowness, and sadness may suggest that morbid depression of mood is the reason for a reduction in liveliness. These clinical features may seem to account for increasing disability. The clinical picture can usually be clarified by careful examination of the mental state. Examination of cognitive functions by more extensive standardized psychological tests may be useful in some cases.
The clinical importance of dementia in Parkinson's disease is that there is a marked increase in disability, with problems arising in areas of functioning not previously affected by motor impairment alone. The development of drug treatments for dementia makes its recognition in Parkinson's disease especially important. Dementia may be accompanied by an increased liability to confusional episodes from the toxic effects of drugs and other causes.
Management of dementia is similar to that for patients suffering from other dementing disorders, but with attention to the presence of a movement disorder. Chapter References
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