title: Associative reinstatement memory measures hippocampal function in Parkinson's Disease.
abstract: In Parkinson's Disease (PD), hippocampal atrophy is associated with rapid cognitive decline. Hippocampal function is typically assessed using memory tests but current clinical tools (e.g., free recall) also rely on executive functions or use material that is not optimally engaging hippocampal memory networks. Because of the ubiquity of executive dysfunction in PD, our ability to detect true memory deficits is suboptimal. Our previous behavioural and neuroimaging work in other populations suggests that an experimental memory task - Associative Reinstatement Memory (ARM) - may prove useful in investigating hippocampal function in PD. In this study, we investigated whether ARM is compromised in PD and we assessed its convergent and divergent validity by comparing it to standardized measures of memory and of attention and executive functioning in PD, respectively. Using fMRI, we also investigated whether performance in PD relates to degree of hippocampal engagement. Fifteen participants with PD and 13 age-matched healthy controls completed neuropsychological testing as well as an ARM fMRI recognition paradigm in which they were instructed to identify word pairs comprised of two studied words (intact or rearranged pairs) and those containing at least one new word (new or half new pairs). ARM is measured by the differences in hit rates between intact and rearranged pairs. Behaviourally, ARM was poorer in PD relative to controls and was correlated with verbal memory measures, but not with attention or executive functioning in the PD group. Hippocampal activation associated with ARM was reduced in PD relative to controls and covaried with ARM scores in both groups. To conclude, ARM is a sensitive measure of hippocampal memory function that is unaffected by attention or executive dysfunction in PD. Our study highlights the benefit of integrating cognitive neuroscience frameworks and novel experimental tasks to improve the practice of clinical neuropsychology in PD.
authors.affiliation: Toronto Western Hospital UHN, 399 Bathurst Street, Toronto, Canada M5T 2S8; Dept. of Psychology, University of Toronto, 100 St. George Street, Toronto, Canada. Electronic address: melanie.cohn@uhn.ca.
authors.forename: Melanie
authors.initials: M
authors.lastname: Cohn
authors.affiliation: Krembil Research Institute, 399 Bathurst Street, Toronto, Canada M5T 2S8.
authors.forename: Irene
authors.initials: I
authors.lastname: Giannoylis
authors.affiliation: Dept. of Experimental Psychology, Ghent University, Henri Dunantlaan 2, Ghent, Belgium.
authors.forename: Maya
authors.initials: M
authors.lastname: De Belder
authors.affiliation: Toronto Western Hospital UHN, 399 Bathurst Street, Toronto, Canada M5T 2S8.
authors.forename: Jean A
authors.initials: JA
authors.lastname: Saint-Cyr
authors.affiliation: Toronto Western Hospital UHN, 399 Bathurst Street, Toronto, Canada M5T 2S8; Krembil Research Institute, 399 Bathurst Street, Toronto, Canada M5T 2S8; Dept. of Psychology, University of Toronto, 100 St. George Street, Toronto, Canada.
authors.forename: Mary Pat
authors.initials: MP
authors.lastname: McAndrews
mesh_terms: D000368:Aged; D001245:Association Learning / Q000502:physiology*; D001288:Attention / Q000502:physiology; D056344:Executive Function; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000000981:diagnostic imaging / Q000209:etiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology*; D021641:Recognition, Psychology; D018709:Statistics, Nonparametric; D014796:Visual Perception
keywords: Associative memory; FMRI; Hippocampus; Parkinson's Disease; Recognition