Automatic affective processing impairments in patients with deficit syndrome schizophrenia

Affective impairments were examined in patients with and without deficit syndrome schizophrenia. Two Emotional Stroop tasks designed to measure automatic processing of emotional information were administered to deficit (n=15) and non-deficit syndrome (n=26) schizophrenia patients classified according to the Schedule for the Deficit Syndrome, and matched non-patient control subjects (n=22). In comparison to non-deficit patients and controls, deficit syndrome patients demonstrated a lack of attention bias for positive information, and an elevated attentional lingering effect for negative information. These findings suggest that positive information fails to automatically capture attention of deficit syndrome patients, and that when negative information captures attention, it produces difficulty in disengagement Attentional abnormalities were significantly correlated with negative symptoms, such that more severe symptoms were associated with less attention bias for positive emotion and a greater lingering effect for negative information. Results are generally consistent with a mood-congruent processing abnormality and suggest that impaired automatic processing may be core to diminished emotional experience symptoms exhibited in deficit syndrome patients.     

Memory and executive function impairments in deficit syndrome schizophrenia

The relationship between deficit syndrome schizophrenia, as determined by the Schedule for the Deficit Syndrome, and impairments in memory and executive function was investigated by administering the Wisconsin Card Sorting Test, the Wechsler Adult Intelligence Test, and the Wechsler Memory Scales to outpatients with deficit (n=33) and non-deficit (n=57) syndrome. A factor analysis of test variables revealed three factors: executive functioning; simple verbal memory; and semantic verbal memory. Results indicated that the deficit group performed significantly worse on the executive functioning factor, but not on either of the verbal memory factors. These findings support the hypothesis that deficit syndrome schizophrenia represents a specific cognitive impairment in executive processing and not necessarily graver global cognitive impairment.     

Neuropsychological impairments predict the clinical course in schizophrenia

To add to the open question whether cognitive impairments predict clinical outcome in schizophrenia, a sample of 125 first episode patients was assessed at the onset and over one year of controlled long-term treatment within a study of the German Research Network on Schizophrenia. No relapse according to predefined criteria occurred within the first year, but a total of 29 patients fulfilled post-hoc criteria of “clinical deterioration”. Impairments in cognitive functioning assessed by the Trail-Making Test B at the onset of long-term treatment differentiated between patients with vs. without later clinical deterioration and proved to be a significant predictor of the clinical course in a regression analysis outperforming initial clinical status as predictor. However, low sensitivity (72%) and specificity (51%) limit possibilities of a transfer to individual predictions. As a linear combination of neuropsychological and psychopathological variables obtained highest predictive validity, such a combination may improve the prediction of the course of schizophrenic disorders and may ultimately lead to a more efficient and comprehensive treatment planning.

     

Theory of mind impairments in patients with deficit schizophrenia

The deficit syndrome, a subgroup within schizophrenia, is characterized by enduring, idiopathic negative symptoms. Theory of mind (ToM), a domain of social cognition, is the ability of attributing mental states to ourselves and other people. ToM impairments have not been investigated earlier in deficit schizophrenia.     

Psychopathology and neuropsychological impairments in deficit and nondeficit schizophrenia of Chinese origin

Deficit schizophrenia is a relatively homogeneous subtype of patients which is considered helpful to explore the pathogenesis of schizophrenia. The aim of the present study was to reexamine the clinical characteristics of deficit (n=30) and nondeficit schizophrenia (n=93) in a Chinese sample and investigate the differences of neurocognitive function among the two subtypes of schizophrenia and the normal controls (n=103). Schizophrenia patients completed the Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Negative Symptoms (SANS) and Scale for the Assessment of Positive Symptoms (SAPS). Additionally, all participants completed an abbreviated version of the Wechsler Adult Intelligence Scale (WAIS-RC) and a neuropsychological test battery examining the executive functions, visuospatial abilities and explicit memory related to the frontal, parietal, and temporal lobe functions. The deficit group received higher scores than the nondeficit group on the BPRS anergia factor and SANS affective flattening, alogia, avolition-apathy, anhedonia-asociality subscales, but not on the SAPS. Both two schizophrenia subgroups performed more poorly on the WAIS-RC and neuropsychological tests than the normal controls. Moreover, deficit patients performed worse than nondeficit patients on the prorated IQ, the Trail Making Test, Wisconsin Card Sorting test and Block Design test. The present study replicated symptom profiles in deficit vs. nondeficit schizophrenia in the Chinese sample. Furthermore, this study suggested that deficit schizophrenia is associated with frontal and parietal lobe impairment, and that temporal lobe dysfunction may be a common basis for cognitive impairment in schizophrenia as a whole.     

Preschool impairments in auditory processing and speech perception uniquely predict future reading problems

Developmental dyslexia is characterized by severe reading and spelling difficulties that are persistent and resistant to the usual didactic measures and remedial efforts. It is well established that a major cause of these problems lies in poorly specified phonological representations. Many individuals with dyslexia also present impairments in auditory temporal processing and speech perception, but it remains debated whether these more basic perceptual impairments play a role in causing the reading problem. Longitudinal studies may help clarifying this issue by assessing preschool children before they receive reading instruction and by following them up through literacy development. The current longitudinal study shows impairments in auditory frequency modulation (FM) detection, speech perception and phonological awareness in kindergarten and in grade 1 in children who receive a dyslexia diagnosis in grade 3. FM sensitivity and speech-in-noise perception in kindergarten uniquely contribute to growth in reading ability, even after controlling for letter knowledge and phonological awareness. These findings indicate that impairments in auditory processing and speech perception are not merely an epiphenomenon of reading failure. Although no specific directional relations were observed between auditory processing, speech perception and phonological awareness, the highly significant concurrent and predictive correlations between all these variables suggest a reciprocal association and corroborate the evidence for the auditory deficit theory of dyslexia.     

Global-local visual processing in schizophrenia: evidence for an early visual processing deficit.

BACKGROUND: Abnormalities in early-stage visual processing might contribute to observed higher neurocognitive deficits in schizophrenia, but to date no clear link has been established. Schizophrenia has been associated with deficits in the magnocellular visual pathway, suggesting a relative bias for processing elemental (local) as opposed to configural (global) aspects of a hierarchical stimulus; however, global-local paradigm studies in schizophrenia have yielded mixed results. METHODS: In the current study, global-local and event-related potential (ERP) procedures were concomitantly used to assess temporal and spatial characteristics of hierarchical visual stimulus processing abnormalities. RESULTS: Patients (n = 24) had slower and less accurate responses to global stimuli than a healthy comparison group (n = 29). They exhibited a marked decrement in N150 ERP amplitude, which correlated with speed of response to global stimuli. They also failed to show an augmented P300 response to local stimuli. CONCLUSIONS: Behavioral and physiological data are consistent and support a global visual processing deficit in schizophrenia. This is manifest at a relatively early stage of visual processing and might relate to physiological disturbances in areas V3/V3a of the extrastriate cortex.     

Reward processing in schizophrenia: a deficit in the representation of value

Patients with schizophrenia demonstrate deficits in motivation and learning that suggest impairment in different aspects of the reward system. In this article, we present the results of 8 converging experiments that address subjective reward experience, the impact of rewards on decision making, and the role of rewards in guiding both rapid and long-term learning. All experiments compared the performance of stably treated outpatients with schizophrenia and demographically matched healthy volunteers. Results to date suggest (1) that patients have surprisingly normal experiences of positive emotion when presented with evocative stimuli, (2) that patients show reduced correlation, compared with controls, between their own subjective valuation of stimuli and action selection, (3) that decision making in patients appears to be compromised by deficits in the ability to fully represent the value of different choices and response options, and (4) that rapid learning on the basis of trial-to-trial feedback is severely impaired whereas more gradual learning may be surprisingly preserved in many paradigms. The overall pattern of findings suggests compromises in the orbital and dorsal prefrontal structures that play a critical role in the ability to represent the value of outcomes and plans. In contrast, patients often (but not always) approach normal performance levels on the slow learning achieved by the integration of reinforcement signals over many trials, thought to be mediated by the basal ganglia.     

Both processing speed and semantic memory organization predict verbal fluency in schizophrenia

We systematically examined the relationship of both lexical retrieval and semantic memory organization to categorical verbal fluency performance in 40 outpatient schizophrenic subjects and 16 healthy controls. Mean choice reaction time (RT) on a lexical decision task was used as a measure of lexical retrieval efficiency. The complexity of semantic memory organization was measured using a Pathfinder semantic network analysis (calculated as the number of inter-node links obtained from a similarity rating task). In the schizophrenia group only, RT and semantic network links were each significantly negatively correlated with fluency and, together, accounted for 23% of the variance in fluency. RT and links were not significantly correlated with one another. Findings were unrelated to age, sex, education, or medication dose. Controlling for IQ reduced but did not abolish the relationship between fluency and network links. We conclude that the restricted verbal output of schizophrenic subjects is related both to impaired lexical retrieval and to variation in semantic memory organization, which partly reflects general intelligence. The statistical independence of the retrieval speed and organizational factors suggests that individuals with schizophrenia differ in the underlying processes that contribute to their reduced verbal fluency.     

Visual object processing in schizophrenia: evidence for an associative agnosic deficit

Early studies suggested visual form perception impairment in schizophrenia. To re-examine this claim and characterise the deficit neuropsychologically, 41 schizophrenic patients were administered tests sensitive to different levels of visual object perception and recognition. Intellectually well-preserved patients were examined separately on these and additional tests. Single case analysis was also applied to four patients showing varying degrees of general intellectual impairment. As a group, the patients showed little impairment on tests of early visual object perception, but greater impairment on higher-level visual processing tests, in particular object recognition and naming. This held true for patients with preserved general intellectual function. Single case analysis suggested that patients with schizophrenia have a selective deficit affecting object recognition and identification, with a pattern similar to visual associative agnosia in neurological patients.     

Working memory constrains abstraction in schizophrenia.

BACKGROUND: Abstraction has long been considered an area of differential cognitive deficit in schizophrenia, primarily because of patients' poor performance on the Wisconsin Card Sorting Test (WCST). Yet, the complexity and multidimensional nature of the WCST increases the likelihood that several different cognitive processes, perhaps mediated by different neural systems, are being tapped. METHODS: In the current study, the Abstraction and Working Memory (AIM) task was designed to disentangle abstraction and working memory so that the effects of each cognitive domain could be independently analyzed. The AIM task and a battery of neuropsychological tests were administered to 62 patients with schizophrenia and 62 matched healthy volunteers. RESULTS: Whereas patients with schizophrenia demonstrated deficits in simple abstraction, they were disproportionately impaired with the addition of a minimal memory requirement. CONCLUSIONS: Group differences on WCST performance appear to be attributable to patients' inability to maintain information over a short delay, before that information is used for more complex cognitive operations.     

A specific deficit in context processing in the unaffected siblings of patients with schizophrenia

BACKGROUND: Understanding the biological basis of complex, heritable illnesses such as schizophrenia is facilitated by sensitive and functionally specific measures of intermediate processes. Context processing is a theoretically motivated construct associated with executive function. Impairments in this process have been associated with dysfunction of the prefrontal cortex. In the present study, we evaluated whether a specific deficit in context processing could be associated with the unexpressed genetic liability to schizophrenia. METHODS: Twenty-four patients with schizophrenia, 24 unaffected siblings and 36 control subjects completed a version of the AX task with (1) a condition that required context processing and (2) an expectancy condition in which intact context processing could lead to errors. RESULTS: Patients and unaffected siblings performed relatively worse in the context processing condition, whereas controls performed relatively worse in the expectancy condition. A double dissociation between siblings and controls (F = 9.5, P<.005) constituted strong evidence of a specific deficit in context processing associated with a familial or genetic liability to schizophrenia. Preliminary evidence of high diagnostic efficiency was also noted (specificity, 38%; and sensitivity, 100%). CONCLUSIONS: Context processing deficits have been associated with dorsolateral prefrontal cortex dysfunctions in schizophrenia. Such a dysfunction may occur even when genetic liability to schizophrenia is unexpressed clinically. The present method of demonstrating a double dissociation may be a useful approach to exploring endophenotypes related to specific cognitive and neural processes that can be measured in ways sensitive to subtle group differences.     

Visual perceptual and working memory impairments in schizophrenia

BACKGROUND: Impairments in working memory have been proposed to underlie a broad range of cognitive deficits seen in schizophrenia. Visual working memory impairments are frequently reported in schizophrenia. Investigations of visual working memory generally assume intact visual information processing, despite evidence of visual perceptual impairments in schizophrenia. In this study, we evaluated the integrity of the perceptual system for object and spatial visual information and the relevant working memory system, after adjusting for individual perceptual performance differences. METHODS: Thirty patients with schizophrenia and 20 healthy control subjects underwent testing using a task of perceptual discrimination of spatial and object visual stimuli. For testing visual working memory, a delay was introduced to the perceptual discrimination task. A thresholding procedure was used so that each subject adequately perceived the information during the working memory test. RESULTS: Subjects with schizophrenia exhibited impaired performance relative to controls for object and spatial visual perceptual discrimination. The extent of impairment was greater for the object than for the spatial test. After controlling for perceptual impairments, the subjects with schizophrenia exhibited impaired performance relative to controls for the spatial working memory test but not the object working memory test. CONCLUSIONS: Findings implicate dysfunction of posterior brain areas that mediate visual perceptual processing and the prefrontal areas involved in the active maintenance of information during delay intervals. However, the systems that govern object and spatial visual perception and working memory appear to be affected differentially by schizophrenia.     

Neuropsychological frontal impairments and negative symptoms in schizophrenia

Negative symptoms have been associated with frontal lobe dysfunction in schizophrenia. However, neuropsychological studies that evaluated the correlation between performance in tests sensitive to the dorsolateral prefrontal cortex (DLPFC) and negative symptoms have shown inconsistent results. Growing evidence has appeared that not only the DLPFC but other prefrontal regions could be involved in schizophrenia. We evaluated schizophrenic patients and healthy controls using three "frontal tests": the Wisconsin Card Sorting Test (WCST), the Iowa Gambling Task (GT) and a Theory of Mind test (Faux Pas), and studied the relationship between performance in these tests and negative symptomatology. Schizophrenic patients had worse performance than normal controls on the WCST, GT and Faux Pas test. The severity of the negative symptoms showed a moderate to high correlation with performance in the Faux Pas test. Our findings support the idea that different prefrontal regions could be affected in people with schizophrenia and that the damage to each of these regions could be, at least in part, independent of the damage to the others. Some negative symptoms could be associated with frontal medial cortex dysfunction.     

Facial emotion processing in schizophrenia: no evidence for a deficit specific to negative emotions in a differential deficit design

People with schizophrenia perform poorly when recognising facial expressions of emotion, particularly negative emotions such as fear. This finding has been taken as evidence of a "negative emotion specific deficit", putatively associated with a dysfunction in the limbic system, particularly the amygdala. An alternative explanation is that greater difficulty in recognising negative emotions may reflect a priori differences in task difficulty. The present study uses a differential deficit design to test the above argument. Facial emotion recognition accuracy for seven emotion categories was compared across three groups. Eighteen schizophrenia patients and one group of healthy age- and gender-matched controls viewed identical sets of stimuli. A second group of 18 age- and gender-matched controls viewed a degraded version of the same stimuli. The level of stimulus degradation was chosen so as to equate overall level of accuracy to the schizophrenia patients. Both the schizophrenia group and the degraded image control group showed reduced overall recognition accuracy and reduced recognition accuracy for fearful and sad facial stimuli compared with the intact-image control group. There were no differences in recognition accuracy for any emotion category between the schizophrenia group and the degraded image control group. These findings argue against a negative emotion specific deficit in schizophrenia.     

Tardive dyskinesia and deficit schizophrenia

Telfer S, Shivashankar S, Krishnadas R, McCreadie RG, Kirkpatrick B. Tardive dyskinesia and deficit schizophrenia. Objective: Despite comparable antipsychotic exposure, some patients experience involuntary movements yet others do not. Negative symptoms have been associated with tardive dyskinesia (TD), but it is not certain whether this is an association with primary negative symptoms or the effects of medications. The aim of the present study was to determine whether patients with deficit schizophrenia (who have primary negative symptoms) are more likely to experience TD than those with non‐deficit schizophrenia. Method: In 2006, all the people with a clinical diagnosis of schizophrenia in Nithsdale, Southwest Scotland, were identified using the ‘key informant’ method. These patients were categorized into those with and without the deficit syndrome and assessed for the presence of TD. Patients were also assessed for akathisia and extrapyramidal side effects. Results: Of the 131 people assessed, 31 were categorized as having deficit schizophrenia (23.7%) and 100 people (76.3%) as non‐deficit. There was no difference between the two groups with regard to age, antipsychotic exposure, and duration of illness. There was a significant association between deficit features and TD with an odds ratio = 2.97 [95% CI 1.128–6.88, P = 0.009]. Conclusion: Our findings support the proposal that the pathological process underlying deficit schizophrenia can predispose to the development of TD.     

Decision-making impairments in adolescents with early-onset schizophrenia

Adolescence is a time of vulnerability for risk-taking behaviors. This is particularly true of adolescents with schizophrenia who present with high rates of substance use as compared to the general population. Using the Iowa Gambling Task (IGT), the authors compared decision-making processes in adolescents with early-onset schizophrenia (onset of psychosis by age 18) to that of healthy volunteers. Fifteen adolescents with schizophrenia (aged 12-21 years) and 25 demographically similar healthy volunteers were administered the IGT. Overall, adolescents with schizophrenia performed significantly worse on the IGT than healthy adolescents as measured by a significant group by block interaction. Post-hoc testing revealed that adolescents with schizophrenia performed more poorly than healthy adolescents during the last two blocks of the task. Mathematical modeling further indicated that adolescents with schizophrenia allocated significantly more attention to monetary gains than losses encountered during the task, suggesting a hypersensitivity to rewards and relative insensitivity to future consequences. This is similar to what has been reported for adults with externalizing forms of psychopathology, such as those who abuse substances. These findings have potential implications for understanding the increased vulnerability for the development of substance abuse in adolescents with schizophrenia.