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Hippocampal subfield atrophy in patients with Parkinson’s disease and psychosis


Psychosis, manifested through formed visual hallucinations or minor hallucinations, is a common non-motor symptom of Parkinson’s disease (PD). The pathogenesis of psychosis in PD remains unclear; however, is possibly linked to structural and functional alterations in the hippocampus. To explore the role of hippocampus in psychosis, a detailed hippocampal subfield analysis was performed on PD patients with (PD-P) and without psychosis (PD-NP), and healthy controls (HC). An automated subfield parcellation was performed on T1 MRI images of 141 subjects (PD-P:42, PD-NP:51, and HC:48). The volumes of 12 subfields on each side were estimated and analyzed between the three groups and were corrected for multiple comparisons using false discovery rates. The volumes were also correlated to psychosis severity and specific neuropsychological tests and finally were employed to predict the psychosis severity in PD-P using a support vector regression (SVR) model. Compared to controls, PD-NP group did not demonstrate any significant differences; however, the PD-P group had significantly lower total hippocampal volume. Bilateral molecular layer, granule cell-dentate gyrus, left subiculum, and hippocampal tail and right CA3, CA4, and HATA illustrated significantly lower volumes, while bilateral hippocampal fissure demonstrated a significant widening. Compared to PD-NP, the PD-P group had higher volume of the bilateral hippocampal fissures. Finally, SVR could significantly predict the psychosis severity from all the subfield volumes. Our findings indicate a higher degeneration of specific hippocampal subfields in PD-P compared to controls and a trend of higher volume of hippocampal fissures in PD-P group than in PD-NP.

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This study is part of a project funded by the Indian Council of Medical research (ICMR). [ICMR/003/304/2013/00694]. Symbiosis International University has received partial support from DST SERB (ECR/2016/000808) for setting up the computing facility. We would like to thank CDAC BRAF for providing their parallel computing facility.

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Correspondence to Pramod Kumar Pal.

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None of the authors have any financial disclosure to make or have any conflict of interest.

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: Correlation of the volumes of hippocampal subfields with scores of neuropsychological tests and psychosis severity (results with p < 0.05). (TIFF 588 KB)

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Lenka, A., Ingalhalikar, M., Shah, A. et al. Hippocampal subfield atrophy in patients with Parkinson’s disease and psychosis. J Neural Transm 125, 1361–1372 (2018).

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  • Parkinson’s disease
  • Psychosis
  • Visual hallucinations
  • Hippocampus