Meta-Analysis of Cognition in Parkinson’s Disease Mild Cognitive Impairment and Dementia Progression

Elizabeth R. Wallace, Suzanne C. Segerstrom, Craig G. van Horne, Frederick A. Schmitt, Lisa M. Koehl

Research output: Contribution to journalReview articlepeer-review

18 Scopus citations


Mild cognitive changes, including executive dysfunction, are seen in Parkinson’s Disease (PD). Approximately 30% of individuals with PD develop Parkinson’s disease dementia (PDD). Mild cognitive impairment (MCI) has been identified as a transitional state between normal cognition and dementia. Although PD-MCI and its cognitive correlates have been increasingly studied as a risk indicator for development of PDD, investigations into the PD-MCI construct have yielded heterogeneous findings. Thus, a typical PD-MCI cognitive profile remains undefined. The present meta-analysis examined published cross-sectional studies of PD-MCI and cognitively normal PD (PD-CN) groups to provide aggregated effect sizes of group test performance by cognitive domain. Subsequently, longitudinal studies examining PD-MCI to PDD progression were meta-analyzed. Ninety-two cross-sectional articles of PD-MCI vs. PD-CN were included; 5 longitudinal studies of PD-MCI conversion to PDD were included. Random effects meta-analytic models were constructed resulting in effect sizes (Hedges’ g) for cognitive domains. Overall performance across all measures produced a large effect size (g = 0.83, 95% CI [0.79, 0.86], t2 = 0.18) in cross-sectional analyses, with cognitive screeners producing the largest effect (g = 1.09, 95% CI [1.00, 1.17], t2 = 0.19). Longitudinally, overall measures produced a moderate effect (g = 0.47, 95% CI [0.40, 0.53], t2 = 0.01), with measures of executive functioning exhibiting the largest effect (g = 0.70, 95% CI [0.51, 0.89], t2 = 0.01). Longitudinal effects were made more robust by low heterogeneity. This report provides the first comprehensive meta-analysis of PD-MCI cognitive outcomes and predictors in PD-MCI conversion to PDD. Limitations include heterogeneity of cross-sectional effect sizes and the potential impact of small-study effects. Areas for continued research include visuospatial skills and visual memory in PD-MCI and longitudinal examination of executive dysfunction in PD-MCI.

Original languageEnglish
Pages (from-to)149-160
Number of pages12
JournalNeuropsychology Review
Issue number1
StatePublished - Mar 2022

Bibliographical note

Funding Information:
The authors would like to thank Dr. Jordan P. Harp and Dr. Ian A. Boggero for their assistance with statistical analyses and Kullen C. Balthrop for his role as an independent data cross-coder.

Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.


  • Cognition
  • Dementia
  • Mild cognitive impairment
  • Parkinson’s disease

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology


Dive into the research topics of 'Meta-Analysis of Cognition in Parkinson’s Disease Mild Cognitive Impairment and Dementia Progression'. Together they form a unique fingerprint.

Cite this