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A quarter of people with Parkinson's disease without dementia have mild cognitive impairment

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What is the frequency of mild cognitive impairment (MCI) in people with Parkinson's disease (PD) without dementia?


1346 people with PD but without dementia from cohorts of patients from eight different centres. Centres which had reported on cognitive function in large (>50 patients), well-defined cohorts of patients were asked to participate. For inclusion they had to use standard clinical criteria for diagnosis of PD and DSM-IV dementia, and use standard neuropsychological tests with norms available or a control group.


Community or clinic settings in the UK (Cambridge and Newcastle), USA (Philadelphia and New York), Norway (Stavanger and ParkWest), Spain (Barcelona) and Italy (Naples); time period not stated.


Different centres used varying tests of cognitive assessment. These were grouped into three cognitive domains: attention/executive function, memory or visuospatial function. If a single cohort had data from more than one test of each domain, the tests with the best psychometric properties, good quality control group or norm data and minimal missing data were used. Participants were also assessed for …

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  • Source of funding Merck Serono.


  • Competing interests None.

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