Longitudinal changes in prospective memory and their clinical correlates at 1-year follow-up in first-episode schizophrenia

Abstract

This study aimed to investigate prospective memory (PM) and the association with clinical factors at 1-year follow-up in first-episode schizophrenia (FES). Thirty-two FES patients recruited from a university-affiliated psychiatric hospital in Beijing and 17 healthy community controls (HCs) were included. Time- and event-based PM (TBPM and EBPM) performances were measured with the Chinese version of the Cambridge Prospective Memory Test (C-CAMPROMPT) at baseline and at one-year follow-up. A number of other neurocognitive tests were also administered. Remission was determined at the endpoint according to the PANSS score ≤ 3 for selected items. Repeated measures analysis of variance revealed a significant interaction between time (baseline vs. endpoint) and group (FES vs. HCs) for EBPM (F(1, 44) = 8.8, p = 0.005) and for all neurocognitive components. Paired samples t-tests showed significant improvement in EBPM in FES (13.1±3.7 vs. 10.3±4.8; t = 3.065, p = 0.004), compared to HCs (15.7±3.6 vs. 16.5±2.3; t = -1.248, p = 0.230). A remission rate of 59.4% was found in the FES group. Analysis of covariance revealed that remitters performed significantly better on EBPM (14.9±2.6 vs. 10.4±3.6; F(1, 25) = 12.2, p = 0.002) than non-remitters at study endpoint. The association between EBPM and 12-month clinical improvement in FES suggests that EBPM may be a potential neurocognitive marker for the effectiveness of standard pharmacotherapy. Furthermore, the findings also imply that PM may not be strictly a trait-related endophenotype as indicated in previous studies.

Prospective memory in individuals with first‐episode schizophrenia: A two‐year longitudinal study

“…Consistent with Cheung et al () and Zhou et al ()'s earlier studies, our findings suggest that the 2 pm types have different trajectories, with time‐based PM improving initially and then plateauing, whereas event‐based PM slowly but progressively improves. We propose several possible reasons for the different trajectories.…”

“…Findings of previous familial studies are inconsistent, with two studies (Wang et al, ; Zhou et al, ) suggesting familial association of PM impairments, but one (Lui et al, ) reporting negative results. On the other hand, previous longitudinal studies (Cheung et al, ; Zhou et al, ) have consistently suggested that time‐based PM is more temporally stable than event‐based PM, even when practice effect was controlled for, using parallel assessments of PM in the control group (Zhou et al, ). Compared with previous studies (Cheung et al, ; Zhou et al, ), our investigation has a longer follow‐up period and more sequential assessments.…”

“…On the other hand, previous longitudinal studies (Cheung et al, ; Zhou et al, ) have consistently suggested that time‐based PM is more temporally stable than event‐based PM, even when practice effect was controlled for, using parallel assessments of PM in the control group (Zhou et al, ). Compared with previous studies (Cheung et al, ; Zhou et al, ), our investigation has a longer follow‐up period and more sequential assessments. The naturalistic trajectory of PM impairment in first‐episode schizophrenia found in our study contributes to the growing body of knowledge on the evolution of PM function in first‐episode schizophrenia.…”

“…There is ample empirical evidence for the existence of PM impairments in patients with both first-episode and chronic schizophrenia (Ordemann et al, 2014). Despite strong evidence supporting that PM satisfies the illness association criterion for a putative trait marker (Gottesman & Gould, 2003), relatively few studies have investigated the other criteria for a putative trait marker, such as familial association (Lui et al, 2011b;Wang et al, 2010;Zhou et al, 2014) and state independence (Cheung et al, 2015;Zhou et al, 2017) of PM. Findings of previous familial studies are inconsistent, with two studies (Wang et al, 2010;Zhou et al, 2014) suggesting familial association of PM impairments, but one (Lui et al, 2011b) reporting negative results.…”

“…In this longitudinal study, we followed up a cohort of first-episode schizophrenia patients for 24 months to clarify the long-term trajectory of PM deficit. Based on earlier findings (Cheung et al, 2015;Zhou et al, 2017), we hypothesized that time-based but not eventbased PM deficits would persist 2 years after schizophrenia onset.…”