Altered pattern of parahippocampal activation during verbal learning in individuals at ultra-high risk of psychosis

Poster B48, Friday, October 21, 11:30 am - 1:00 pm, Le Baron

Cathy Davies1, Robin Wilson1, Elizabeth Appiah-Kusi1, Matthijs Bossong1, Paul Allen1, Philip McGuire1, Sagnik Bhattacharyya1; 1Institute of Psychiatry, King's College London

Background: Impairments of verbal learning and memory are key neuropsychological deficits in those at ultra-high risk of psychosis (UHR). Previous functional magnetic resonance imaging (fMRI) studies have focused on verbal recognition memory, finding functional alterations in the medial temporal lobes. No studies to date have investigated the pattern of neural activation in response to repeated associative encoding and recall trials (verbal learning). Our objective was to test whether individuals at UHR show an altered pattern of brain activation in the neural substrates of verbal associative learning using fMRI. Methods: We studied 17 UHR individuals and 19 healthy controls using fMRI whilst performing a verbal paired associates learning task. The outcome measures of interest were brain activation (blood-oxygen-level-dependent response) over repeated encoding and recall conditions of the task, recall performance and severity of positive psychotic symptoms. Results: In healthy controls, we observed a linear increase in engagement of the right parahippocampal gyrus over repeated recall trials. This trend was directly reversed in those at UHR of psychosis (P= 0.02). Severity of psychotic symptoms in the UHR individuals were negatively correlated with recall task performance (r = -0.77, P= 0.001). Functional differences occurred in the absence of difference in recall performance between the groups. Conclusion: These results suggest that impairments of verbal associative learning in those at UHR are associated with an aberrant pattern of activation in the parahippocampal gyrus over repeated recall trials. These findings complement existing studies that have shown altered engagement of the parahippocampal gyrus during verbal memory recognition.

Topic Area: Neuroimaging

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