Differential patterns of contextual organization of memory in first-episode psychosis

Abstract

Contextual information is used to support and organize episodic memory. Prior research has reliably shown memory deficits in psychosis; however, little research has characterized how this population uses contextual information during memory recall. We employed an approach founded in a computational framework of free recall to quantify how individuals with first episode of psychosis (FEP, N = 97) and controls (CON, N = 55) use temporal and semantic context to organize memory recall. Free recall was characterized using the Hopkins Verbal Learning Test-Revised (HVLT-R). We compared FEP and CON on three measures of free recall: proportion recalled, temporal clustering, and semantic clustering. Measures of temporal/semantic clustering quantified how individuals use contextual information to organize memory recall. We also assessed to what extent these measures relate to antipsychotic use and differentiated between different types of psychosis. We also explored the relationship between these measures and intelligence. In comparison to CON, FEP had reduced recall and less temporal clustering during free recall (p < 0.05, Bonferroni-corrected), and showed a trend towards greater semantic clustering (p = 0.10, Bonferroni-corrected). Within FEP, antipsychotic use and diagnoses did not differentiate between free recall accuracy or contextual organization of memory. IQ was related to free recall accuracy, but not the use of contextual information during recall in either group (p < 0.05, Bonferroni-corrected). These results show that in addition to deficits in memory recall, FEP differed in how they organize memories compared to CON.

Fig. 1

Contextual influences on Memory Recall Organization. CON use temporal context to a greater extent during free recall than FEP (Left). FEP use semantic context to a greater extent during free recall then CON (Right). In the box-and-whisker plots the horizontal line represents the median, the edges of the box indicate the upper and lower quartiles, and the median is represented by the solid horizontal lines, the edges of box indicate the upper and lower quartiles, and the vertical lines represent the range (excluding outliers which are indicated by a dot). Asterisks (**) indicates significance of p < 0.001, Bonferroni-corrected; ~ indicates a trend of p ≤ 0.10, Bonferroni-corrected

Fig. 2

IQ relates to free recall accuracy but not use of temporal or semantic context in FEP. There was a significant relationship between IQ (left) and free recall accuracy in FEP. However, there was no relationship with IQ (middle/right) and the use of temporal or semantic context during free recall. The solid line indicates the best linear fit and the shaded area represents the 95% confidence interval. Asterisks (**) indicates significance of p < 0.001, Bonferonni-corrected; n.s indicates p > 0.10, uncorrected