Objectives Parkinson’s disease (PD) is the second most common neurodegenerative disorder and is further associated with progressive cognitive decline. In respect to motor phenotype, there is some evidence that akinetic-rigid PD is associated with a faster rate of cognitive decline in general and a greater risk of developing dementia.
The objective of this study was to examine cognitive profiles among patients with PD by motor phenotypes and its relation to cognitive function.
Methods Demographic, clinical and neuropsychological cross-sectional baseline data of the DEMPARK/LANDSCAPE study, a multicentre longitudinal cohort study of 538 patients with PD were analysed, stratified by motor phenotype and cognitive syndrome. Analyses were performed for all patients and for each diagnostic group separately, controlling for age, gender, education and disease duration.
Results Compared with the tremor-dominant phenotype, akinetic-rigid patients performed worse in executive functions such as working memory (Wechsler Memory Scale-Revised backward; p=0.012), formal-lexical word fluency (p=0.043), card sorting (p=0.006), attention (Trail Making Test version A; p=0.024) and visuospatial abilities (Leistungsprüfungssystem test 9; p=0.006). Akinetic-rigid neuropsychological test scores for the executive and attentive domain correlated negatively with non-tremor motor scores. Covariate-adjusted binary logistic regression analyses showed significant odds for PD-mild cognitive impairment for not-determined as compared with tremor-dominant (OR=3.198) and akinetic-rigid PD (OR=2.059). The odds for PD-dementia were significant for akinetic-rigid as compared with tremor-dominant phenotype (OR=8.314).
Conclusion The three motor phenotypes of PD differ in cognitive performance, showing that cognitive deficits seem to be less severe in tremor-dominant PD. While these data are cross-sectional, longitudinal data are needed to shed more light on these differential findings.
- Mild cognitive impairment
- cognitive profiles
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Contributors Manuscript: Writing of the first draft: JW; Review and critique: all other authors. Research project: Conception, organisation and execution: all authors except JW, PN, JD. Statistical analysis: Design: JW, IAH, PN, KR, JD; Execution: JW, IAH, PN, KR, JD.
Funding The DEMPARK study was funded by an unrestricted grant from Novartis and a grant from the International ParkinsonFonds (Deutschland) GmbH (IPD). The continuation of the study (LANDSCAPE) is funded by the German Ministry for Education and Research (BMBF 01GI1008C). KR was funded by the German Federal Ministry of Education and Research (BMBF 01GQ1402).
Competing interests GD has received lecture fees from Boston Scientific and has been serving as a consultant for Boston Scientific. He received royalties from Thieme Publishers. He is a government employee and receives through his institution funding for his research from the German Research Council, the German Ministry of Education and Research, and Medtronic. KW received reimbursement of congress fees from BIAL and Desitin; and grants from the Federal Ministry of Education and Research and the German Research Foundation.
Patient consent Not required.
Ethics approval The study was conducted in compliance with the Helsinki Declaration (1997; https://www.wma.net). The study protocol was approved by the Ethics Committee of the Philipps University Marburg (approval number 178/07) in March 2009 and subsequently by the local ethics committees of the participating hospitals.
Provenance and peer review Not commissioned; externally peer reviewed.