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Abstract
Objective: To determine whether cognitive impairment in Parkinson disease (PD) and Alzheimer disease (AD) derives from the same network pathology.
Methods: We analyzed 18F-fluorodeoxyglucose PET scans from 40 patients with AD and 40 age-matched healthy controls from the Alzheimer’s Disease Neuroimaging Initiative and scanned an additional 10 patients with AD and 10 healthy controls at The Feinstein Institute for Medical Research to derive an AD-related metabolic pattern (ADRP) analogous to our previously established PD cognition-related pattern (PDCP) and PD motor-related pattern (PDRP). We computed individual subject expression values for ADRP and PDCP in 89 patients with PD and correlated summary scores for cognitive functioning with network expression. We also evaluated changes in ADRP and PDCP expression in a separate group of 15 patients with PD scanned serially over a 4-year period.
Results: Analysis revealed a significant AD-related metabolic topography characterized by covarying metabolic reductions in the hippocampus, parahippocampal gyrus, and parietal and temporal association regions. Expression of ADRP, but not PDCP, was elevated in both AD groups and correlated with worse cognitive summary scores. Patients with PD showed slight ADRP expression, due to topographic overlap with the network underlying PD motor-related pattern degeneration, but only their PDCP expression values increased as cognitive function and executive performance declined. Longitudinal data in PD disclosed an analogous dissociation of network expression.
Conclusions: Cognitive dysfunction in PD is associated with a specific brain network that is largely spatially and functionally distinct from that seen in relation to AD.
GLOSSARY
- AD=
- Alzheimer disease;
- ADNI=
- Alzheimer’s Disease Neuroimaging Initiative;
- ADRP=
- Alzheimer disease–related pattern;
- ANOVA=
- analysis of variance;
- FDG=
- 18F-fluorodeoxyglucose;
- FIMR=
- Feinstein Institute for Medical Research;
- MCI=
- mild cognitive impairment;
- MCI(−)=
- cognitively intact;
- MCI(m)=
- mild cognitive impairment involving multiple cognitive domains;
- MCI(s)=
- mild cognitive impairment involving a single cognitive domain;
- MMSE=
- Mini-Mental State Examination;
- PD=
- Parkinson disease;
- PDCP=
- Parkinson disease cognition-related pattern;
- PDD=
- Parkinson disease dementia;
- PDRP=
- Parkinson disease motor-related pattern;
- RMANOVA=
- repeated-measures analysis of variance
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf. (also available as supplemental material).
Supplemental data at Neurology.org
- Received March 18, 2016.
- Accepted in final form July 18, 2016.
- © 2016 American Academy of Neurology
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