Evaluation of verbal list learning as a predictor of psychosis

A systematic review of premorbid cognitive functioning and its timing of onset in schizophrenia spectrum disorders

Cognitive impairments are core features of established schizophrenia spectrum disorders (SSD). However, it remains unclear whether specific cognitive functions are differentially impaired pre-onset and at what age these impairments can be detected. The purpose of this review was to elucidate these issues through a systematic summary of results from longitudinal studies investigating impairment in specific cognitive domains as antecedents of SSD. Relevant studies were identified by electronic and manual literature searches and included any original study of cognitive domains any time pre-onset of SSDs that included a control group. Effect sizes were calculated by domain for studies comparing high-risk participants who developed SSD with those who did not. The strongest evidence for impairment pre-onset was for mental processing speed, verbal learning and memory, executive function, and social cognition. Some verbal impairments, like language abilities at age 3 and verbal learning and memory at age 7, may develop as static deficits. Conversely, some non-verbal impairments, like mental processing speed, visuospatial abilities, and visual working memory manifest as developmental lag and become significant later in life. Most effect sizes were small to moderate, except for verbal fluency (d' = 0,85), implying this impairment as central in high-risk participants who develop SSD. The present review documents extensive cognitive impairments pre-onset of SSD, and that these impairments start early in life, in line with the neurodevelopmental hypothesis of schizophrenia. Increased knowledge about cognitive impairments preonset can provide a better basis for understanding the complex pathogenesis of SSD as well as informing cognitive remediation programs.

Intersection of verbal memory and expressivity on cortical contrast and thickness in first episode psychosis

BACKGROUND

Longitudinal studies of first episode of psychosis (FEP) patients are critical to understanding the dynamic clinical factors influencing functional outcomes; negative symptoms and verbal memory (VM) deficits are two such factors that remain a therapeutic challenge. This study uses white-gray matter contrast at the inner edge of the cortex, in addition to cortical thickness, to probe changes in microstructure and their relation with negative symptoms and possible intersections with verbal memory.

METHODS

T1-weighted images and clinical data were collected longitudinally for patients (N = 88) over a two-year period. Cognitive data were also collected at baseline. Relationships between baseline VM (immediate/delayed recall) and rate of change in two negative symptom dimensions, amotivation and expressivity, were assessed at the behavioral level, as well as at the level of brain structure.

RESULTS

VM, particularly immediate recall, was significantly and positively associated with a steeper rate of expressivity symptom decline (r = 0.32, q = 0.012). Significant interaction effects between baseline delayed recall and change in expressivity were uncovered in somatomotor regions bilaterally for both white-gray matter contrast and cortical thickness. Furthermore, interaction effects between immediate recall and change in expressivity on cortical thickness rates were uncovered across higher-order regions of the language processing network.

CONCLUSIONS

This study shows common neural correlates of language-related brain areas underlying expressivity and VM in FEP, suggesting deficits in these domains may be more linked to speech production rather than general cognitive capacity. Together, white-gray matter contrast and cortical thickness may optimally inform clinical investigations aiming to capture peri-cortical microstructural changes.

The role of set-shifting in auditory verbal hallucinations

BACKGROUND

Auditory verbal hallucinations (AVHs) are a cardinal characteristic of psychosis. Recent research on the neuropsychological mechanism of AVHs has focused on source monitoring failure, but a few studies have suggested the involvement of attention, working memory, processing speed, verbal learning, memory, and executive functions. In this study we examined the neuropsychological profile of patients with AVHs, assuming that the mechanism underlying this symptom could be a dysfunction of specific cognitive domains.

METHODS

A large neuropsychological battery including set-shifting, working memory, processing speed, attention, fluency, verbal learning and memory, and executive functions was administered to 90 patients with psychotic disorders and 44 healthy controls. The group of patients was divided into two groups: 46 patients with AVHs in the current episode and 44 who denied auditory hallucinations or other modalities in the current episode. AVHs were assessed with the Psychotic Symptom Rating Scales (PSYRATS); the Launay-Slade Hallucination Scale was used to measure long-term propensity to auditory verbal hallucination-like experiences (HLEs) in the sample.

RESULTS

Patients showed poorer performances on all neuropsychological measures compared to the healthy controls' group. In the original dataset without missing data (n=58), patients with AVHs (n=29) presented poorer set shifting and verbal learning, higher levels of visual attention, and marginally significant poorer semantic fluency compared to patients without AVHs (n=29). In the logistic model on the multiple imputed dataset (n=90, 100 imputed datasets), lower capacity of set shifting and semantic fluency distinguished patients with AVHs from those without them.

CONCLUSIONS

Patients experiencing persistent AVHs might fail to shift their attention away from the voices; poorer semantic fluency could be a secondary deficit of set-shifting failure.