Influence Of Different Cut-Off Values On The Diagnosis Of Mild Cognitive Impairment In Parkinson'S Disease
Parkinson’s disease (PD) is recognized to have a wide range of non-motor features that include cognitive functions. Evidence currently shows that a slight decline in cognition can enhance the changeover to dementia in Parkinson’s disease. This does not necessarily mean that patients who have Parkinson’s disease will develop dementia. Different definitions for Parkinson’s disease, mild cognitive impairment (MCI) differs from predicting whether one will develop dementia or not. The purpose of this study is to “to compare the frequency of PD-MCI and subtypes of PD-MCI by use of varying cut-off values, and second, to analyze how this variation of cut-off values might affect the interpretation of the clinical profile investigated in the PD-MCI group”.
The study consisted of 107 patients that were recruited from the Outpatient Clinic of the Department of Neurodegenerative Disorders, University of Tuebingen. Patients were only tested if they had Parkinson’s disease, were older than 50 years old, had decent hearing/visual abilities, and German was their main language. Patients were excluded from the study if they had other neurological diseases that affect the central nervous system, had surgery for Parkinson’s, or if their score for a Mini-Mental State Examination was < 26. They were also excluded if their score was higher and the likeliness of dementia was to occur based off level II criteria of the Movement Disorder Society Task Force. This criteria outlines the diagnosis of Parkinson’s Disease. With that being said, in the end, a total of 101 individuals were analyzed.
Many tests were given to try and get results for this study. A neuropsychological test was given within two weeks of motor assessments that was carried out on medication. Also, a test-battery was composed to check known affected areas of mediated functions in Parkinson’s disease. The attention domain was concluded by the GO-NOgo condition as well as the Alertness tests. Planning ability was tested by a trail-making test, set-maintenance abilities were tested off a Nernberger Altersinventar (NAI) test, and working memory performance was tested by the digit slam part if the NAI, it was also tested by word-list recognition. Furthermore, “praxis and visual function” was evaluated by three tests: the copying of line drawings, the delayed recall of the drawings, and the object decision part of the Visual Object and Space Perception Battery.
Results showed that patients scored lowest on both logical memory performance tests. Almost all patients scored below the cut-off value, the stricter the cut-off was the less individuals were labeled with Parkinson’s disease, mild cognitive impairment. The likelihood of patients having more severe cognitive impairment in at least one test score overlapped with the likelihood of patients having less severe cognitive impairments in at least two test scores per domain. “By use of the most liberal cut-off value, nearly all (92%) of their non-demented PD patients were defined as cognitively impaired, compared to less than 16% of subjects in the healthy population (by definition)”, stated the study.
Since my grandmothers brother has Parkinson’s disease, I found this study to be interesting. Although Parkinson’s disease is more common in the elderly, it would be interesting to have a study on the few percentage of individuals that do have Parkinson’s disease at a young age.
