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Longitudinal study of normal cognition in Parkinson disease
Pigott K, Rick J, Xie SX, Hurtig H, Chen-Plotkin A, Duda JE, Morley JF, Chahine LM et al.. Neurology, 2015-09-11
Topic: Risk, prevention and care in population studies
Objective To report the rates and predictors of progression from normal cognition to either mild cognitive impairment (MCI) or dementia using standardized neuropsychological methods. Methods A prospective cohort of patients diagnosed with Parkinson disease (PD) and baseline normal cognition was assessed for cognitive decline, performance, and function for a minimum of 2 years, and up to 6. A panel of movement disorders experts classified patients as having normal cognition, MCI, or dementia, with 55/68 (80.9%) of eligible patients seen at year 6. Kaplan-Meier curves and Cox proportional hazard models were used to examine cognitive decline and its predictors. Results We enrolled 141 patients, who averaged 68.8 years of age, 63% men, who had PD on average for 5 years. The cumulative incidence of cognitive impairment was 8.5% at year 1, increasing to 47.4% by year 6. All incident MCI cases had progressed to dementia by year 5. In a multivariate analysis, predictors of future decline were male sex (p = 0.02), higher Unified Parkinson's Disease Rating Scale motor score (p ≤ 0.001), and worse global cognitive score (p Conclusions Approximately half of patients with PD with normal cognition at baseline develop cognitive impairment within 6 years and all new MCI cases progress to dementia within 5 years. Our results show that the transition from normal cognition to cognitive impairment, including dementia, occurs frequently and quickly. Certain clinical and cognitive variables may be useful in predicting progression to cognitive impairment in PD.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Pigott, K., Rick, J., Xie, S. X., Hurtig, H., Chen-Plotkin, A., Duda, J. E., et al. (2015). Longitudinal study of normal cognition in Parkinson disease. Neurology. https://doi.org/10.1212/wnl.0000000000002001
Vancouver
Pigott K, Rick J, Xie SX, Hurtig H, Chen-Plotkin A, Duda JE, et al. Longitudinal study of normal cognition in Parkinson disease. Neurology. 2015. doi:10.1212/wnl.0000000000002001. PMID: 26362285.
BibTeX
@article{pigott2015-26362285,
author = {Pigott, K. and Rick, J. and Xie, S. X. and Hurtig, H. and Chen-Plotkin, A. and Duda, J. E. and Morley, J. F. and Chahine, L. M. and others},
title = {{Longitudinal study of normal cognition in Parkinson disease}},
journal = {Neurology},
year = {2015},
doi = {10.1212/wnl.0000000000002001},
pmid = {26362285},
url = {https://doi.org/10.1212/wnl.0000000000002001}
}
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Key findings
- Results We enrolled 141 patients, who averaged 68.8 years of age, 63% men, who had PD on average for 5 years.
- Our results show that the transition from normal cognition to cognitive impairment, including dementia, occurs frequently and quickly.
Why it matters
In 141 people with Parkinson disease who started with normal thinking, 8.5% had cognitive impairment after one year and 47.4% by year six, and every new case of mild cognitive impairment had become dementia by year five. Men, people with worse movement scores and people with lower baseline cognitive scores were more likely to decline. That is an association, not a cause. This is a natural-history study of Parkinson disease: it tests no treatment, and its rates should not be applied to Alzheimer's disease.
Study details
- Study designprospective cohort
- Participants141
- Effect size80.9%; 8.5%; 47.4%
- Evidence strengthModerate
How this study scored 68/100
Published in a leading specialty journal, and it is a prospective cohort study, followed forward from enrollment. Scored zero for randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| Study design | 7 / 12 | A prospective cohort study, followed forward from enrollment |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2015 — within 20 year(s) of the newest study here |
| Sample size | 2 / 4 | 141 participants |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 5 / 7 | Cited 253 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 19.5 citations a year over 13 year(s) since 2015 |
| Impact for its field and year | 4 / 6 | Cited 17.7× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 9 other studies in this library |
| Still being cited | 3 / 4 | Cited 56 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Daniel A. Weintraub: h-index 115 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University of Pennsylvania: institution h-index 1,859 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 4 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 26362285) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 68 / 100 | — |
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