Face and object visual working memory deficits in first-episode schizophrenia correlate with multiple neurocognitive performances

Abstract

Background Working memory (WM) deficit is considered a core feature and cognitive biomarker in patients with schizophrenia. Several studies have reported prominent object WM deficits in patients with schizophrenia, suggesting that visual WM in these patients extends to non-spatial domains. However, whether non-spatial WM is similarly affected remains unclear. Aim This study primarily aimed to identify the processing of visual object WM in patients with first-episode schizophrenia. Methods The study included 36 patients with first-episode schizophrenia and 35 healthy controls. Visual object WM capacity, including face and house WM capacity, was assessed by means of delayed matching-to-sample visual WM tasks, in which participants must distribute memory so that they can discriminate a target sample. We specifically examined their anhedonia experience by the Temporal Experience of Pleasure Scale and the Snaith-Hamilton Pleasure Scale. Cognitive performance was measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Results Both face and house WM capacity was significantly impaired in patients with schizophrenia. For both tasks, the performance of all the subjects was worse under the high-load condition than under the low-load condition. We found that WM capacity was highly positively correlated with the performance on RBANS total scores (r=-0.528, p=0.005), RBANS delayed memory scores (r=-0.470, p=0.013), RBANS attention scores (r=-0.584, p=0.001), RBANS language scores (r=-0.448, p=0.019), Trail-Making Test: Part A raw scores (r=0.465, p=0.015) and simple IQ total scores (r=-0.538, p=0.005), and correlated with scores of the vocabulary test (r=-0.490, p=0.011) and scores of the Block Diagram Test (r=-0.426, p=0.027) in schizophrenia. No significant correlations were observed between WM capacity and Positive and Negative Syndrome Scale symptoms. Conclusions Our research found that visual object WM capacity is dramatically impaired in patients with schizophrenia and is strongly correlated with other measures of cognition, suggesting a mechanism that is critical in explaining a portion of the broad cognitive deficits observed in schizophrenia.