Objective: To determine whether hippocampal subfield volumes in non-demented Parkinson’s Disease (PD) are primarily predicted by cognition or CSF β-amyloid 1–42 (Aβ42) levels.

Background: The role of Alzheimer’s Disease pathology in PD patients is still unclear. PD patients with dementia (PDD) have greater hippocampal atrophy compared to patients without dementia, but results are controversial. Similarly, lowered CSF Aβ42 levels in PD patients have been shown to be associated with a rapid cognitive decline compared to controls, but not all studies confirm this finding. While both hippocampal atrophy and CSF Aβ42 levels have been implicated in cognitive decline in PD, the relationship between these factors has been sparsely studied.

Method: Data of 45 non-demented PD patients was examined. All patients underwent CSF, MRI, motor, and neuropsychological assessments. Freesurfer 6.0 was used to segment the hippocampus into 12 distinct subfields. Hippocampal subfield volumes were compared between cognitive groups (mild cognitive impairment, PD-MCI vs. no cognitive impairment) and Aβ42 groups (cut-off 600 pg/mL) using regression models. Partial correlations correcting for intra-cranial volume (ICV) were used for analysis of exploratory associations between variables.

Results: Of all 45 patients, 16 (35.6%) had PD-MCI; 26 (57.8%) had abnormal Aβ42 burden. Nine patients (56.3%) with PD-MCI had pathological Aβ42. The hippocampal–amygdaloid transition area (β= −0.28, 95% CI −0.56 to −0.02) and the CA1 region (β= −0.23, 95% CI −0.44 to −0.02) were both significantly predicted by cognitive group status, independent of ICV and disease duration [1]. Aβ42 levels did not significantly predict any hippocampal subfields. Impaired cognition on memory, spatial working memory, executive functioning, and language, domains was associated with smaller volumes of hippocampal subfields. An additional negative correlations between the subiculum and total tau levels (r= −0.37, 95% CI −0.60 to −0.09) was found.

Conclusion: Cognitive diagnosis significantly predicted hippocampal volumes in PD, while no associations were found with Aβ42. The cognitive profile associated with hippocampal volume loss is heterogenic. Our results confirmed previous data showing smaller volumes of the right hippocampal–amygdaloid transition area and CA1 regions in PD patients with mild cognitive impairment compared to those without cognitive deficits.

References: [1] Becker, S., Granert, O., Timmers, M., Pilotto, A., Van Nueten, L., Roeben, B., Salvadore, G., Galpern, W.R., Streffer, J., Scheffler, K., Maetzler, W., Berg, D., & Liepelt-Scarfone, I. Association of Hippocampal Subfields, CSF Biomarkers and Cognition in Non-Demented Parkinson’s Disease Patients. (2021). Neurology, 96(6), e904–e915. doi: 10.1212/WNL.0000000000011224

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MDS Abstracts - https://www.mdsabstracts.org/abstract/association-between-hippocampal-subfields-csf-biomarkers-and-cognition-in-non-demented-parkinsons-patients/