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

Abstract

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.

Hippocampal Subfield Volumes in Major Depressive Disorder Adolescents with a History of Suicide Attempt

“…Therefore, the increased bilateral hippocampal fissure volume observed in SA may imply impending whole hippocampus atrophy. This kind of lesion has also been reported in patients with first-episode schizophrenia [42], Alzheimer's disease [43][44][45], and Parkinson's disease [46], which is consistent with disrupted neurodevelopment in this brain region. Longitudinal studies are needed to follow the possible secondary reduction in hippocampal volume caused by hippocampal developmental disruption that happened in early life.…”

Microstructural abnormalities of substantia nigra in Parkinson's disease: A neuromelanin sensitive MRI atlas based study

“…The diagnosis of idiopathic PD was based on the UK Parkinson's Disease Society Brain Bank criteria (Hughes, Daniel, Kilford, & Lees, ) and confirmed by a trained movement disorder specialist (author PKP). Patients included in this study have been part of other studies (Lenka et al, ; Shah et al, ) from this group and all patients and controls provided informed consent prior to recruitment in the original projects. Data usage for this study was reviewed and approved by the review board at NIMHANS.…”

MRI of Motor and Nonmotor Therapy‐Induced Complications in Parkinson's Disease

“…Thus, an integrated model for visual hallucinations occurrence has been proposed, including impaired visual input and visual processing, reduced control on the sleep–wake cycle by the brain stem, cognitive dysfunction, and influence of dopaminergic drugs . In treated PD patients with visual hallucinations, structural MRI studies showed reduced GM volume in the visual associative areas, including the lingual gyrus and superior parietal regions, but also in the hippocampus and temporal cortex . Moreover, in these patients, Bejr‐Kasem and colleagues demonstrated the presence of an aberrant functional connectivity between posterior regions of the default mode network and the visual‐processing area.…”