title: Regional vulnerability of hippocampal subfields and memory deficits in Parkinson's disease.
abstract: Neuropathological studies show the hippocampus is affected in Parkinson's disease (PD), with the second subfield of the cornu armonis (CA2) being the most involved. Our aims were to assess in vivo volumes of different hippocampal subfields in patients with PD with and without visual hallucinations using MRI and test their association with verbal learning and long-term recall. A total of 18 nondemented PD patients, 18 nondemented PD patients with visual hallucinations and 18 neurologically unimpaired elderly controls matched by age and gender were enrolled in this study. We assessed the volumes of seven hippocampal subfields on MRI, including the cornu armonis (CA) sectors, subiculum, presubiculum, and the dentate gyrus (DG) using a novel technique that enables automated volumetry. The CA2-3 and CA4-DG subfields were significantly smaller in both groups of patients, while the subiculum was only reduced in PD patients with visual hallucinations, compared to controls. Significant correlations were found between learning performance and CA2-3 as well as CA4-DG volumes in the whole patient sample. These data show there is regional atrophy of specific hippocampal subfields in PD, which is more severe and further extends to the subiculum in patients with visual hallucinations. Our findings indicate that learning deficits are associated with volume loss in subfields that act as input regions in the hippocampal circuit, suggesting that degeneration in these regions could be responsible for cognitive dysfunction in PD.
authors.affiliation: Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Barcelona, Spain.
authors.forename: Joana B
authors.initials: JB
authors.lastname: Pereira
authors.forename: Carme
authors.initials: C
authors.lastname: Junqué
authors.forename: David
authors.initials: D
authors.lastname: Bartrés-Faz
authors.forename: Blanca
authors.initials: B
authors.lastname: Ramírez-Ruiz
authors.forename: Maria-Jose
authors.initials: MJ
authors.lastname: Marti
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tolosa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006212:Hallucinations / Q000209:etiology; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000473:pathology*; D012720:Severity of Illness Index; D013223:Statistics as Topic
keywords: CA2-3; CA4-DG; Parkinson's disease; learning; subiculum