Search

Although meta-analyses suggest that schizophrenia (SZ) is associated with a more severe neurocognitive phenotype than mood disorders such as bipolar disorder, considerable between-subject heterogeneity exists in the phenotypic presentation of these deficits across mental illnesses. Indeed, it is unclear whether the processes that underlie cognitive dysfunction in these disorders are unique to each disease or represent a common neurobiological process that varies in severity. Here we used latent profile analysis (LPA) across 3 distinct cognitive domains (cognitive control, episodic memory, and visual integration; using data from the CNTRACS consortium) to identify distinct profiles of patients across psychotic illnesses. LPA was performed on a sample of 223 psychosis patients (59 with Type I bipolar disorder, 88 with SZ, and 76 with schizoaffective disorder). Seventy-three healthy control participants were included for comparison but were not included in sample LPA. Three latent profiles ("Low," "Moderate," and "High" ability) were identified as the underlying covariance across the 3 domains. The 3-profile solution provided highly similar fit to a single continuous factor extracted by confirmatory factor analysis, supporting a unidimensional structure. Diagnostic ratios did not significantly differ between profiles, suggesting that these profiles cross diagnostic boundaries (an exception being the Low ability profile, which had only one bipolar patient). Profile membership predicted Brief Psychiatric Rating Scale and Young Mania Rating Scale symptom severity as well as everyday communication skills independent of diagnosis. Biological, clinical and methodological implications of these findings are discussed., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Contour integration (CI) refers to the process that represents spatially separated elements as a unified edge or closed shape. Schizophrenia is a psychiatric disorder characterized by symptoms such as hallucinations, delusions, disorganized thinking, inappropriate affect, and social withdrawal. Persons with schizophrenia are impaired at CI, but the specific mechanisms underlying the deficit are still not clear. Here, we explored the hypothesis that poor patient performance owes to reduced feedback or impaired longer-range lateral connectivity within early visual cortex--functionally similar to that found in 5- to 6-year old children. This hypothesis predicts that as target element spacing increases from .7 to 1.4° of visual angle, patient impairments will become more pronounced. As a test of the prediction, 25 healthy controls and 36 clinically stable, asymptomatic persons with schizophrenia completed a CI task that involved determining whether a subset of Gabor elements formed a leftward or rightward pointing shape. Adjacent shape elements were spaced at either .7 or 1.4° of visual angle. Difficulty in each spacing condition depended on the number of noise elements present. Patients performed worse than controls overall, both groups performed worse with the larger spacing, and the magnitude of the between-group difference was not amplified at the larger spacing. These results show that CI deficits in schizophrenia cannot be explained in terms of a reduced spatial range of integration, at least not when the shape elements are spaced within 1.5°. Later-developing, low-level integrative mechanisms of lateral connectivity and feedback appear not to be differentially impaired in the illness.

The goal of the current project was to further develop a measure of gain control--the Contrast-Contrast Effect (CCE)--for use in clinical studies of schizophrenia. The CCE is based on an illusion in which presenting a medium contrast patch surrounded by a high-contrast patch induces individuals to perceive that center patch as having lower contrast than when the patch is presented in isolation. Thus, in the CCE, impaired gain control should lead to more accurate perceptions of the center patch. We tested 132 individuals with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, schizophrenia or schizoaffective disorder and 130 demographically similar healthy controls. The results indicated that the CCE effect can be obtained with standard equipment, simplified scoring, and a short interstimulus interval (100 ms), revealing a robust suppression of perceived contrast of the center patch when surrounded by a high-contrast annulus. Furthermore, we found a significant reduction in the effect of the high-contrast surround among individuals with schizophrenia, though the effect size was smaller than original reported by Dakin. However, when we eliminated subjects who performed poorly on "catch" trials that controlled for off-task performance, the reduced surround effect among patients was no longer significant in the main analyses. Importantly, this suggests that at least part of the reduced surround effect (if not all) in schizophrenia could be attributable to impaired attentional mechanisms that contribute to off-task performance. Additional analyses suggested that the length of the task could be shortened without losing power to detect surround effects in healthy individuals.

Equivalent versions of the Complex Figure Test (CFT) are useful for assessing change over time in constructional skills, planning, spatial organization, and visual-spatial memory while minimizing practice effects. To address the need for an equivalent version of the CFT to the Rey, the present study compared copy and 45 min-delayed recall accuracy scores of the Rey and Mack CFTs obtained from 245 adults involved in a study of the neuropsychological correlates of sleep apnea and its treatment. Accuracy scores did not significantly differ between individuals with and without sleep apnea. Also, there was no significant difference between copy or recall accuracy scores obtained on the Rey and Mack CFTs. Similar correlations were found between relevant demographic factors, estimated IQ, and accuracy scores for both CFTs. These data suggest that the Mack figure may be a useful alternative to the Rey CFT.

The effects of aging on visuospatial attention were investigated with event-related brain potentials (ERPs). A central arrow pointed towards (75% valid cues) or away from (25% invalid cues) the location of upcoming visual targets to which subjects made two choice discriminations. Young and older adults responded faster following valid than invalid cues. The absolute magnitude of the cueing effect was larger for older than young subjects, but cueing effects were similar between groups when estimated proportionally to overall response time. Under the present conditions, the electrophysiological manifestations of visuospatial attention were similar for young and older adults. Early ERP components following the target stimulus (P1, N1, Nd1) were slower for older than young subjects, but amplitude was similarly affected by cueing in each group. The temporal correspondence between component latencies and the observed cueing effects are consistent with theories positing that attention amplifies the sensory gain of early perceptual processes. The observation that aging slowed latency of the ipsilateral but not the contralateral P1, is consistent with age differences in interhemispheric transfer times. A broadly distributed 200-400 ms validity effect on ERP amplitude was similar between groups in timing, spatial distribution, and magnitude. The 200-400 ms attention effect appeared to be a modulation of the P3 in younger subjects, as earlier observed. However, the present study dissociated the 200-400 ms attention effects from the P3 component because the P3 did not peak until 526 ms in older subjects.

Twenty-four depressed and twenty-three nondepressed male patients rated pleasantness of slides varying in hedonic content. Depressed patients rated positive slides as less pleasant and less arousing but did not differ from nondepressed patients in subjective response to normatively unpleasant images. Analysis of videotapes of facial expressions while watching the slide images showed that depressives exhibited more negative expressions than nondepressives to negative slides. Groups did not differ in facial expression to positive stimuli, but neither group displayed much affect to those stimuli. These data suggest a possible dissociation between self-reported and observable responsivity to emotional stimuli in depression and that diminished subjective emotional response in depression is restricted to hedonically positive stimuli and does not reflect generalized diminished emotional responsivity. These results also imply that clinical assessment of emotional responsivity in depression should be made using modalities in addition to observer evaluation of expressed emotion.

Objective: Previous studies of attention/information processing impairments in schizophrenia suggest that patients with the deficit syndrome should be characterized by impaired performance on measures of visual information processing. Therefore, the authors examined whether two measures of visual information processing, a degraded stimulus version of the continuous performance test and a forced choice span of apprehension task, were uniquely related to the deficit syndrome., Method: Performance on the continuous performance test and span of apprehension task was examined in 20 deficit and 56 nondeficit patients with schizophrenia and in 27 subjects in a normal comparison group., Results: Deficit patients performed significantly less well than both nondeficit patients and the normal comparison group on the continuous performance test and span of apprehension task. There were no significant differences between the nondeficit patients and the normal group on the continuous performance test, but nondeficit patients performed significantly less well on the span of apprehension task than the normal group. Differences between the deficit and nondeficit patients in performance on the continuous performance test and span of apprehension task were not related to total scores on the Brief Psychiatric Rating Scale factor 1 or on the Thought, Language, and Communication scale or to neuroleptic level., Conclusions: The results suggest that deficit patients are uniquely characterized by impaired performance on the continuous performance test. The deficit patients' differential performance on the continuous performance test may be related to either an inability to activate and allocate attention or an impairment in the perceptual organization of visual information.

Schizophrenic and control subjects were tested on two-flash fusion (TFF) and visual backward masking (VBM) tasks in a repeated measures design. Each subject was tested in a single session. Both tasks used the same equipment and stimuli. There was no difference between the groups in their ability to detect the presence of two separate stimuli in the TFF task. Schizophrenic subjects did require longer interstimulus intervals (ISI) than control subjects to accurately report one of the two targets in the VBM task. Analysis of individual targets reveals that the VBM deficit is a function of the similarity of the target and mask. The more feature detail discrimination necessary, the longer an ISI is required in VBM. The data are interpreted as supporting the conclusion that since the groups did not differ in their performance of the TFF task, which would also have been affected by a sensory abnormality, the deficit in VBM must be explained by reference to a higher level of information processing. The VBM deficit is a failure to decode the target stimulus, and is not simply a function of abnormalities due to an overactive transient channel system.