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. 2015 Aug;21(8):899-904.
doi: 10.1016/j.parkreldis.2015.05.020. Epub 2015 May 27.

Cognitive reserve and β-amyloid pathology in Parkinson disease

Carolyn Lucero  1 , Meghan C Campbell  2 , Hubert Flores  3 , Baijayanta Maiti  4 , Joel S Perlmutter  5 , Erin R Foster  6
Affiliations

Cognitive reserve and β-amyloid pathology in Parkinson disease

Carolyn Lucero et al. Parkinsonism Relat Disord. 2015 Aug.

Abstract

Introduction: Dementia in Parkinson disease (PD) is associated with abnormal accumulation of proteins, including β-amyloid, in cortical regions. High cognitive reserve capacity may protect cognition from β-amyloid and delay the onset of dementia. We tested the cognitive reserve theory in PD by determining whether educational attainment, a proxy for cognitive reserve, modifies the correlation between cortical β-amyloid accumulation and cognitive impairment.

Methods: PD participants (N = 155) underwent MRI to quantify brain volume and [(11)C] PiB PET imaging to quantify fibrillar β-amyloid deposition. Mean cortical binding potentials (MCBP) were calculated for each participant, with higher scores indicating more fibrillar β-amyloid. Global cognitive function was assessed using the Clinical Dementia Rating (CDR) and Mini-Mental State Examination (MMSE). Multiple linear regression analysis was used to determine whether education modified the relationship between MCBP and cognitive function after controlling for brain volume.

Results: MCBP interacted with educational attainment to predict scores on each of the cognitive outcome measures (ps ≤ 0.02). Post-hoc analysis revealed that the effect of MCBP on cognitive function changed once the level of education reached 16 years. For participants with less than 16 years of education (n = 68), higher MCBP correlated with worse cognitive function, with MCBP accounting for 8-30% of the variance in MMSE and CDR scores (ps ≤ 0.02). For participants with at least 16 years of education (n = 87), MCBP did not correlate with MMSE or CDR scores (R(2)s < 0.02, ps ≥ 0.17).

Conclusion: These findings provide support for the cognitive reserve theory in PD and suggest that education may protect PD patients' cognition against cortical β-amyloid pathology.

Keywords: Cognition; Cognitive reserve; Dementia; Education; Parkinson's disease.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Predicted relation between MCBP and (A) MMSE, (B) CDR, (C) CDR-SB for participants with M ± 2.5 SD). MCBP = Mean cortical binding potential; MMSE = Mini-Mental State Examination; CDR = Clinical Dementia Rating global score; CDR-SB = Clinical Dementia Rating sum of boxes score
See this image and copyright information in PMC

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