Objective: To evaluate the effect of cognitive reserve (CR) in patients with Parkinson’s disease (PD) without dementia.

Background: CR concept is a principal factor explaining the mismatch between preserved cognitive status and neuropathological damage in patients with Alzheimer’s disease: high premorbid education and active stimulating lifestyle provide a buffer against cognitive deficits secondary to neurodegenerative changes. A synergistic action between Aβ and α-synuclein deposition is probably implicated in the origin of cognitive impairment in Parkinson´s disease.

Method: We recruited PD patients, aged 55-79, <10 years of disease duration, without dementia, nor significant depression. A comprehensive neuropsychological assessment was completed. Patients were classified according to their CR (Cognitive Reserve Questionnaire). All patients were evaluated (by MDS-UPDRS III) ON medication and PET-MR-18F-flutemetamol (for brain amyloid assessment). Differences were calculated with Mann-Whitney U test. Voxel wise comparison was performed with SPM12.

Results: We included 46 non-demented PD patients, 12 were female; 18 had a superior CR (≥15) and 28 a low CR (<15). Mean age was 68.2(±5.4) and disease duration 5.5(±2.1) years. MDS-UPDRS III ON scored 21.26(±8.77). Levodopa equivalent daily dose was 628.30(±287.77) mg/24h, GDS scored 7.72(±5.16) and mean CR 13.46(±4.9). Neuropsychological assessment revealed significant poorer performance in test assessing attention, executive function, language, visuospatial function, and memory in the low vs high CR group (p< 0.05). Voxel wise comparison showed higher amyloid burden in the right inferior frontal, right middle temporal, and right anterior cingulate cortex in PD patients with superior vs low CR (p<0.001, uncorrected).

Conclusion: PD patients without dementia with superior CR appear to tolerate higher cerebral amyloid load compared to patients with low CR. Further studies with a higher number of patients are warranted.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-reserve-in-non-demented-patients-with-parkinsons-disease-might-protect-against-amyloid-burden-effect-on-cognition/