Sustained attention and positive formal thought disorder in schizophrenia

Formal thought disorder in patients with first-episode schizophrenia: Results of a one-year follow-up study

Formal thought disorder (FTD) refers to abnormal speech patterns that can be characterized by deficiencies in thought organization and direction. The present study aimed to assess the factor structure of FTD and to examine its relationship with cognition and clinical features at first admission in patients with first-episode schizophrenia. We also examined the course of FTD during the twelve months after first admission. We assessed FTD using the alogia items of the Scale for the Assessment of Negative Symptoms and FTD items of the Scale for the Assessment of Positive Symptoms in 160 drug-naïve patients. A three-factor structure as a disorganization factor, poverty factor, and verbosity factor were found in principal component analysis. The poverty factor was correlated negatively with executive functions, attention, and global cognition. The poverty factor was also correlated with global functioning. Admission FTD factor scores were not related to global functioning and work/study status at one year. The positive-FTD score decreased from admission to the third month, but no change occurred from the third to the twelfth month. The negative-FTD score did not differ throughout the follow-up. Our findings showed that FTD had three factors. Each factor had a different relationship with cognition and functioning.

M. Staging of Schizophrenia With the Use of PANSS: An International Multi-Center Study

INTRODUCTION

A specific clinically relevant staging model for schizophrenia has not yet been developed. The aim of the current study was to evaluate the factor structure of the PANSS and develop such a staging method.

METHODS

Twenty-nine centers from 25 countries contributed 2358 patients aged 37.21 ± 11.87 years with schizophrenia. Analysis of covariance, Exploratory Factor Analysis, Discriminant Function Analysis, and inspection of resultant plots were performed.

RESULTS

Exploratory Factor Analysis returned 5 factors explaining 59% of the variance (positive, negative, excitement/hostility, depression/anxiety, and neurocognition). The staging model included 4 main stages with substages that were predominantly characterized by a single domain of symptoms (stage 1: positive; stages 2a and 2b: excitement/hostility; stage 3a and 3b: depression/anxiety; stage 4a and 4b: neurocognition). There were no differences between sexes. The Discriminant Function Analysis developed an algorithm that correctly classified >85% of patients.

DISCUSSION

This study elaborates a 5-factor solution and a clinical staging method for patients with schizophrenia. It is the largest study to address these issues among patients who are more likely to remain affiliated with mental health services for prolonged periods of time.

Neurocognitive and linguistic correlates of positive and negative formal thought disorder: A meta-analysis

Executive dysfunction and language impairment are the most prominent neuropsychological models of formal thought disorder (FTD) in schizophrenia. However, available studies have provided contradictory findings regarding the accuracy of these models. Furthermore, specific neurocognitive underpinnings of positive FTD (PosFTD) and negative FTD (NegFTD) are not clear. Following the systematic review of schizophrenia studies, a random-effects meta-analysis of the relationship between FTD and neurocognition/language in schizophrenia was conducted in 52 reports including 2805 patients. Neurocognition was significantly associated with both PosFTD (r = -0.21, CI = -0.14 to -0.27) and NegFTD (r = -0.24, CI = -0.18 to -0.30). Both PosFTD (r = ranged from -0.18 to -0.27) and NegFTD (r = ranged from -0.19 to -0.23) were significantly correlated with verbal memory, visual memory, attention, and processing speed. In meta-analyses of executive functions, PosFTD was significantly associated with working memory (r = -0.21), planning (r = -0.19), and inhibition (r = -0.21) and NegFTD was significantly associated with planning (r = -0.27), fluency (r = -0.27), and working memory (r = -0.24). In meta-analyses of linguistic variables, PosFTD was associated with deficits in syntactic comprehension (r = -0.27) and semantic processing (r = -0.18). In contrast, NegFTD was associated only with semantic comprehension (r = -0.21). Both PosFTD and NegFTD were significantly associated with executive dysfunction, neurocognitive deficits and semantic dysfunction but syntactic deficits were more specific to PosFTD. There were also some distinct patterns of relationships between the pattern of executive dysfunction and types of FTD. Fluency deficit was associated more strongly with NegFTD and poor inhibition was more specifically related to PosFTD. Current findings suggest that neurocognitive and linguistic correlates of PosFTD and NegFTD might be partly different.

Herpes simplex virus 1 infection and valacyclovir treatment in schizophrenia: Results from the VISTA study

BACKGROUND

Several studies have implicated herpes simplex virus-type 1 (HSV-1) in the pathophysiology of schizophrenia. A recent trial demonstrated that the anti-viral medication valacylovir, which prevents replication of activated HSV-1, improved selected cognitive deficits in people with schizophrenia. In this study, we examined demographic and illness related differences between HSV-1 positive versus HSV-1 negative subjects with early phase schizophrenia and attempted to replicate the previous valacyclovir treatment results in this population.

METHODS

170 subjects with schizophrenia (HSV-1 positive N = 70; HSV-1 negative N = 96) from 12 US sites participated in the HSV-1 positive versus negative comparisons, and were randomized 1:1 to valacyclovir (1.5 g BID) or placebo for a 16-week, double-blind efficacy trial. The primary endpoints were working and verbal memory.

RESULTS

The HSV-1 positive group, as compared to the HSV-1 negative group, were older (p < 0.001) with fewer males (p = 0.003), and had a longer duration of illness (p = 0.008), more positive symptoms (p = 0.013), poorer quality of life (p = 0.034) and more impairment on the letter-number sequencing test, which is a measure of working memory (p = 0.045). Valacyclovir failed to significantly improve any of the cognitive indices, symptom or functioning measures.

CONCLUSIONS

HSV-1 sero-positivity appears to be a marker of a subgroup with a more severe form of schizophrenia. Valacyclovir was not efficacious in the study, perhaps because the herpes virus was in the dormant, non-activated state and therefore non-responsive to valacyclovir effects. ClinicalTrials.gov Identifier: NCT02008773.

Formal thought disorders: from phenomenology to neurobiology

Formal thought disorder (FTD) is present in most psychiatric disorders and in some healthy individuals. In this Review, we present a comprehensive, integrative, and multilevel account of what is known about FTD, covering genetic, cellular, and neurotransmitter effects, environmental influences, experimental psychology and neuropsychology, brain imaging, phenomenology, linguistics, and treatment. FTD is a dimensional, phenomenologically defined construct, which can be clinically subdivided into positive versus negative and objective versus subjective symptom clusters. Because FTDs have been traditionally linked to schizophrenia, studies in other diagnoses are scarce. Aetiologically, FTD is the only symptom under genetic influence in schizophrenia as shown in linkage studies, but familial communication patterns (allusive thinking) have also been associated with the condition. Positive FTDs are related to synaptic rarefication in the glutamate system of the superior and middle lateral temporal cortices. Cortical volume of the left superior temporal gyrus is decreased in patients with schizophrenia who have positive FTD in structural MRI studies and shows reversed hemispheric (right more than left) activation in functional MRI experiments during speech production. Semantic network dysfunction in positive FTD has been demonstrated in experiments of indirect semantic hyperpriming (reaction time). In acute positive FTD, antipsychotics are effective, but a subgroup of patients have treatment-resistant, chronic, positive or negative FTD. Specific psychotherapy as treatment for FTD has not yet been developed. With this solid data on the pathogenesis of FTD, we can now implement clinical studies to treat this condition.

Could PANSS be a useful tool in the determining of the stages of schizophrenia? A clinically operational approach

Staging in schizophrenia might be an important approach for the better treatment and rehabilitation of patients. The purpose of this study was to empirically devise a staging approach in a sample of stabilized patients with schizophrenia. One hundred and seventy patients aged ≥18 years (mean = 40.7, SD = 11.6) diagnosed by DSM-5 criteria were evaluated with the Positive and Negative Syndrome Scale (PANSS). Principal components analysis (PCA) with varimax rotation was used. The model was examined in the total sample and separately across a hypothesized stage of illness based on three age groups and between the two sexes. The PCA revealed a six factor structure for the total sample: 1) Negative, 2) Positive, 3) Depression and anxiety, 4) Excitement and Hostility, 5) Neurocognition and 6) Disorganization. The separate PCAs by stage of illness and sex revealed different patterns and quality of symptomatology. The Negative and Positive factors were stable across all examined groups. The models corresponding to different stages differed mainly in terms of neurocognition and disorganization and their interplay. Catatonic features appear more prominent in males while in females neurocognition takes two forms; one with disorganization and one with stereotype thinking with delusions. This study suggests that the three arbitrary defined stages of illness (on the basis of age) seem to reflect a progress from a preserved insight and more coherent mental functioning to disorganization and eventually neurocognitive impairment. Sexes differ in terms of the relationship of psychotic features with neurocognition. These results might have significant research and clinical implications.

Distinct Neuropsychological Correlates in Positive and Negative Formal Thought Disorder Syndromes: The Thought and Language Disorder Scale in Endogenous Psychoses

The correlation of formal thought disorder (FTD) symptoms and subsyndromes with neuropsychological dimensions is as yet unclear. Evidence for a dysexecutive syndrome and semantic access impairments has been discussed in positive FTD, albeit focusing mostly on patients with schizophrenia. We investigated the correlation of the full range of positive and negative as well as subjective and objective FTD with neuropsychological domains in different patient groups. Patients with ICD-10 schizophrenia (n = 51), depression (n = 51), and bipolar mania (n = 18), as well as healthy subjects (n = 60), were interviewed with the Rating Scale for the Assessment of Objective and Subjective Formal Thought and Language Disorder (TALD) and assessed using a multidimensional neuropsychological test battery (executive function, semantic and lexical verbal fluency, attention, working memory, and abstract thinking). Partial correlation analysis, controlling for age and word knowledge, revealed significant results for the objective positive FTD dimension and executive dysfunctions. Objective negative FTD was associated with deficits in lexico-semantic retrieval, as well as attention and working memory dysfunctions. The results suggest that different neuropsychological substrates correlate with the multidimensional and phenomenologically different FTD syndromes. FTD is a complex, multidimensional syndrome with a variety of neuropsychological impairments, which should be accounted for in future studies investigating the pathogenesis of FTD.

Paying attention to MMN in schizophrenia

The aim of this review is to explore the phenomenon of reduced mismatch negativity (MMN) in persons with schizophrenia and the possible relationship it has with attention impairments. In doing so we discuss (i) the prediction error account of MMN, (ii) reduced MMN as a faulty predictive processing system in persons with schizophrenia, (iii) the role of these systems in relevance filtering and attentional resource protection, (iv) attentional impairments in persons with schizophrenia, and (v) research that has explored MMN and attention in schizophrenia groups. Our review of the literature suggests that no study has appropriately examined the functional impact of smaller MMN in schizophrenia on the performance of a concurrent attention task. We conclude that future research should explore this notion further in the hope that it might embed MMN findings within outcomes of functional significance to individuals with the illness and those providing treatment. This article is part of a Special Issue entitled SI: Prediction and Attention.

Executive function as predictors of persistent thought disorder in first-episode schizophrenia: a one-year follow-up study

Language disorganization is an important clinical indicator of acute psychosis, yet the longitudinal course and pathogenesis are not well understood. Executive dysfunction has been suggested as a vital contributor to formal thought disorder (FTD) and may serve as a stable predictor of symptomatic risk. The paper reports a one-year prospective study of language disorganization in sixty patients with first-episode schizophrenia-spectrum disorders and investigates executive function as a predictor of persistent FTD one year after illness onset. FTD was captured using the Clinical Language Disorder Rating Scale (CLANG), which segregates language abnormalities into three empirically validated levels: syntactic, semantic, and production. After one year, patients' syntactic and semantic deficits were substantially reduced, but production impairments persisted. Patients' improvement of semantic impairment was associated with reduced disorganized symptoms while production impairment was associated with negative symptoms. We further identified two different patterns of baseline executive function predictors for both residual semantic and production impairment. We found that sustained FTD at the semantic level was predicted by both sustained attention and planning at illness onset, while residual production failure was only predicted by sustained attention. In conclusion, the present paper documents the distinct characteristics of psycholinguistic levels in FTD and isolates two different patterns of executive function predictors for persistent semantic and production language disorganization at follow-up. The findings help to disentangle FTD dimensions at different levels of language production processes, which provide clinical implications for targeting patients at risk for prolonged FTD concordant upon executive dysfunction at illness onset.

Reverse translation of the rodent 5C-CPT reveals that the impaired attention of people with schizophrenia is similar to scopolamine-induced deficits in mice

Attentional dysfunction in schizophrenia (SZ) is a core deficit that contributes to multiple cognitive deficits and the resulting functional disability. However, developing procognitive therapeutics for neuropsychiatric disorders have been limited by a 'translational gap'--a lack of cognitive paradigms having cross-species translational validity and relevance. The present study was designed to perform an initial validation of the cross-species homology of the 5-choice Continuous Performance Test (5C-CPT) in healthy nonpsychiatric comparison subjects (NCS), SZ patients and mice under pharmacologic challenge. The 5C-CPT performance in SZ patients (n=20) was compared with age-matched NCS (n=23). The effects of the general muscarinic receptor antagonist scopolamine on mice (n=21) performing the 5C-CPT were also assessed. SZ subjects exhibited significantly impaired attention in the 5C-CPT, driven by reduced target detection over time and nonsignificantly increased impulsive responding. Similarly, scopolamine significantly impaired attention in mice, driven by reduced target detection and nonsignificantly increased impulsive responding. Scopolamine also negatively affected accuracy and speed of responding in mice, although these measures failed to differentiate SZ vs. NCS. Thus, mice treated with scopolamine exhibited similar impairments in vigilance as seen in SZ, although the differences between the behavioral profiles warrant further study. The availability of rodent and human versions of this paradigm provides an opportunity to: (1) investigate the neuroanatomic, neurochemical and genomic architecture of abnormalities in attention observed in clinical populations such as SZ; (2) develop and refine animal models of cognitive impairments; and (3) improve cross-species translational testing for the development of treatments for these impairments.

Kraepelin and Bleuler had it right: people with schizophrenia have deficits sustaining attention over time

An inability to sustain attention was noted in the original clinical descriptions of schizophrenia, but the vast majority of experimental studies have failed to report a performance decrement over time, calling this observation into question. To test for such deficits when task conditions conform to basic science taxonomy for the validity of sustained attention tasks, a dynamic stimulus array was presented in which targets, differing subtly from standard stimuli, were presented infrequently and unpredictably. Both people with schizophrenia (PSZ, n=40) and healthy control subjects (HCS, n=29) displayed a reduction in hit rate and an increase in reaction time (RT) from the first to the second 5-min period. Thereafter, the hit rate of HCS recovered and remained stable, while that of PSZ continued to decline. When performance at task onset was equated between groups, the decrement over time in PSZ remained of the same robust magnitude. Thus, when the nature of the task challenges sustaining attention over time, PSZ display a clear deficit in this ability.

Suppression of Prepotent Motor Responses Implicate Frontostriatal Dysfunction in Schizophrenia and Its Subtypes

Schizophrenia has been identified as a disorder of the frontostriatal system with impairments in both sustained and selective attention (Bradshaw, 2001). The Sustained Attention to Response Task (SART), which required occasional withholding of an ongoing frequent response when a specified digit occurred, was completed by patients with a clinical diagnosis of schizophrenia (N = 52) and matched controls (N = 46). Relative to controls, participants with schizophrenia responded less frequently and made more impulsive errors. Their correct responses were slower on average, with greater variability in timing. Speed of response was unrelated to neuroleptic medication dosage. The slow responses exhibited by patients with schizophrenia were interpreted as reflecting primarily motor frontostriatal circuit dysfunction, and dysfunction of the lateral orbitofrontal/anterior cingulate circuit is implicated in poor impulse control. To address the heterogeneity of symptoms in schizophrenia, symptom dimension scores (positive, negative and disorganised) were used to determine whether symptom dimensions were associated with differential performance on the SART. Higher negative symptoms were related to increased miss errors on the SART whereas higher disorganised and positive symptom scores were unrelated to performance on this measure. An association between negative symptoms and increased miss errors may be considered indicative of dysfunction of the anterior cingulate circuit, considered to be linked to response inattention, apathy, reduced initiative and focused attention. Implications of this research for understanding the neuroanatomical basis for schizophrenia and its subtypes are discussed.

Disorganization and reality distortion in schizophrenia: a meta-analysis of the relationship between positive symptoms and neurocognitive deficits

BACKGROUND

Factor analytic studies have shown that in schizophrenia patients, disorganization (e.g., conceptual disorganization and bizarre behavior) is a separate dimension from other types of positive symptoms such as reality distortion (delusions and hallucinations). Although some studies have found that disorganization is more strongly linked to neurocognitive deficits and poor functional outcomes than reality distortion, the findings are not always consistent.

METHODS

A meta-analysis of 104 studies (combined n=8015) was conducted to determine the magnitude of the relationship between neurocognition and disorganization as compared to reality distortion. Additional analyses were conducted to determine whether the strength of these relationships differed depending on the neurocognitive domain under investigation.

RESULTS

The relationship between reality distortion and neurocognition was weak (r=-.04; p=.03) as compared to the moderate association between disorganization and neurocognition (r=-.23; p<.01). In each of the six neurocognitive domains that were examined, disorganization was more strongly related to neurocognition (r's range from -.20 to -.26) than to reality distortion (r's range from .01 to -.12).

CONCLUSIONS

The effect size of the relationship between neurocognition and disorganization was significantly larger than the effect size of the relationship between neurocognition and reality distortion. These results hold across several neurocognitive domains. These findings support a dimensional view of positive symptoms distinguishing disorganization from reality distortion.

Preattentional processes and disorganization in schizophrenia: Influence of a 6-week risperidone treatment

INTRODUCTION

Visual orientation and attention are impaired in schizophrenia. Engagement and disengagement of attention and the ability to prompt responses to a stimulus in patients before and after six weeks of risperidone were compared to controls.

METHODS

Ten unmedicated (nine naïve) schizophrenic patients, and eleven controls performed 1) A visual orienting task, the Cued Target Detection task (CTD), with the detection of a visual stimulus in valid, invalid, no cue and double cue trials, two conditions for fixation offset for a modulation of visual fixation: Gap: 200 ms before target; No Gap: simultaneous with target, 2) Choice Reaction Time (CRT 0.5 and 2 s delays).

RESULTS

At baseline, patients showed longer RT than controls in CRT, but not in CTD, with in CTD, no facilitation of RT with the gap procedure. The alertness index was almost null in CTD-Gap and comparable to controls in CTD-No Gap. Efficiency to detect attended stimuli (CTD-No Gap) and warning effect (CRT 0.5 s) were negatively correlated to disorganization. After treatment, readiness to act in CRT had decreased. In CTD-No Gap, change in PANSS disorganization was correlated to an increased validity index, change in negative sub-score was correlated to decreased attention cost.

CONCLUSION

Untreated patients displayed a deficit of Gap effect and a slowing in sustained attention. Disorganization interfered with warning and visual detection. After treatment, its improvement and negative symptoms improvement were associated with better visual detection. These alterations in visual orienting provide new evidence for an oculomotor dysregulation of attentional engagement in schizophrenia.

The head-centered meridian effect: Auditory attention orienting in conditions of impaired visuo-spatial information

This paper examines the characteristics of spatial attention orienting in situations of visual impairment. Two groups of subjects, respectively schizophrenic and blind, with different degrees of visual spatial information impairment, were tested. In Experiment 1, the schizophrenic subjects were instructed to detect an auditory target, which was preceded by a visual cue. The cue could appear in the same location as the target, separated from it respectively by the vertical visual meridian (VM), the vertical head-centered meridian (HCM) or another meridian. Similarly to normal subjects tested with the same paradigm (Ferlazzo, Couyoumdjian, Padovani, and Olivetti Belardinelli, 2002), schizophrenic subjects showed slower reactions times (RTs) when cued, and when the target locations were on the opposite sides of the HCM. This HCM effect strengthens the assumption that different auditory and visual spatial maps underlie the representation of attention orienting mechanisms. In Experiment 2, blind subjects were asked to detect an auditory target, which had been preceded by an auditory cue, while staring at an imaginary point. The point was located either to the left or to the right, in order to control for ocular movements and maintain the dissociation between the HCM and the VM. Differences between crossing and no-crossing conditions of HCM were not found. Therefore it is possible to consider the HCM effect as a consequence of the interaction between visual and auditory modalities. Related theoretical issues are also discussed.

Two new scales of formal thought disorder in schizophrenia

Information provided by patients and respective carers may help to understand formal thought disorder (FTD) in schizophrenia. Two scales, one for patients (FTD-patient) and one for carers (FTD-carer), were constructed to assess pragmatics, cognitive, paralinguistic, and non-verbal aspects of communication. In the first scale the patients themselves assess their verbal communication; in the second scale the carer assesses the speech of the respective patient. Both scales exhibited internal reliability and evidence of good test-retest reliability. Higher total scores on both scales (FTD-patient and FTD-carer) were significantly associated with positive FTD, but not with negative FTD. Principal component analysis of the scales yielded a multidimensional structure. It is suggested that FTD in schizophrenia may be associated with a range of deficits (e.g. pragmatics, lexical activation, working memory, sustained attention). These scales, in conjunction with the clinician's assessment, can provide a more comprehensive picture of FTD in schizophrenia, revealing its dimensions and making it possible to establish associations between symptoms of FTD and neuropsychological, neurophysiologic, and neuroimaging data. In addition, they provide service users' and carers' perspectives for the assessment of communication in schizophrenia.

Effect of schizotypy on cognitive performance and its tuning by COMT val158 met genotype variations in a large population of young men

BACKGROUND

Mirroring schizophrenia, specific dimensions of schizotypy are related to cognitive dysfunction. The relation of schizotypy and state psychopathology to cognitive performance and its link to catechol-O-methyltransferase (COMT) val(158) met genotype variations was studied in a large sample of young men.

METHODS

State psychopathology and schizotypy were assessed with self-rated questionnaires. Cognitive performance was assessed with tests of reasoning ability, sustained attention, and verbal and spatial working memory. Subjects were genotyped for the val(158) met polymorphism of the gene for COMT (low enzymatic activity met/met, intermediate met/val, and high val/val).

RESULTS

The val/val group had higher scores in measures of state psychopathology as well as negative and disorganized schizotypy dimensions, whereas there was no effect of COMT genotype on cognitive performance measures. Structural equation modeling showed that cognitive performance accuracy but not speed decreased with increasing negative schizotypy, increased with increasing paranoid schizotypy, and was not affected by state psychopathology. Increasing val loading resulted in a dose-dependent increase in the factor loading for the relation between negative schizotypy and cognitive performance accuracy.

CONCLUSIONS

Different schizotypal phenotypes had opposing relations to cognitive performance in the population. COMT genotype modulated the relation between the negative schizotypal phenotype and cognitive performance.

Attention deficits in bipolar disorder: a comparison based on the Continuous Performance Test

Although attentional deficits measured by Continuous Performance Tests (CPTs) have been observed in patients with bipolar disorder, their relationship with clinical state is not well understood. The identical pairs Continuous Performance Test (CPT-IP) shows particular promise as a measure sensitive to trait abnormalities in attentional function. In this study, the CPT-IP was administered to 27 patients with bipolar disorder (22 type I, 5 type II) and 25 demographically matched healthy comparison subjects, in order to assess the presence and nature of attentional deficits as a function of mood symptoms. Results showed significantly impaired CPT performance in bipolar patients compared with healthy subjects. Patients made fewer hits (p < 0.01), were slower to respond (p < 0.007), and had poorer discrimination (p < 0.05) and bias (p < 0.006) than comparison subjects. Severity of mania and depression was not correlated with any of the CPT measures. Our findings suggest that attentional dysfunction may be a trait deficit associated with bipolar illness. However, within-subjects longitudinal studies examining fluctuations in performance over time are needed.

Attention disorders in schizophrenia

In order to clarify the feature of attention disorders in schizophrenia, two tasks (X and AX) of the Continuous Performance Test (CPT) were given to 36 schizophrenic patients and 25 healthy controls. The schizophrenic patients performed considerably less well than normal controls. Performances were expressed in indices such as omission and commission errors, reaction time and discriminability. Among errors, omission in both the X and AX tasks was found to be an index that varied in reaction time, indicating difficulty in sustaining attention. Omission was found to act as a state-dependent index of schizophrenia in relation to inattentiveness in clinical settings and emotional disturbance in interpersonal situations. Commission, in contrast, differed between the two tasks, acting as an index of disinhibition of reaction in the X task, and of disturbance of the capacity and allocation of attention in the AX task. Commission was also thought to be an index related to thought disorder during episodes of acute schizophrenia, that is, it reflects an essential pathology in schizophrenia.

Sustained attention deficits as markers of genetic susceptibility to schizophrenia

This article reviews recent evidence regarding the potential of the visual sustained attention deficits as measured by the Continuous Performance Test (CPT) as an endophenotype of the genetic susceptibility to schizophrenia. Findings in community subjects indicate that sustained attention develops during the primary school ages, reaches its maximum around early adolescence, and declines with age after adulthood. The assertion that CPT performance deficits, and especially on the more difficult versions, are reliable and valid genetic susceptibility indicators of schizophrenia is supported by the following results: 1) CPT deficits are present in schizophrenic patients, are particularly associated with negative and disorganized symptoms, and deficits on the more difficult CPT versions are not amenable to neuroleptic treatment; 2) subjects with schizotypal personality features also exhibit CPT deficits, which are specifically associated with the negative factor of schizotypy; 3) a substantial proportion of nonpsychotic relatives of schizophrenic patients (19-34%) have CPT deficits, which can also be predicted from their probands' CPT performance. Thus, using a CPT deficits as an endophenotype of schizophrenia would not only provide a valuable measure of genetic risk, but would also greatly enhance our understanding of etiology, and may help identify susceptibility genes for schizophrenia.

Written but not oral verbal production is preserved in young schizophrenic patients

The aim of this study is to discover whether the language capabilities of young schizophrenic patients are more affected in speaking than in writing or whether the disorders are equivalent in the two modes. To do this, we compared spoken and written descriptions of pictures obtained from 10 schizophrenic patients with those produced by 10 control subjects. These productions were analysed on the basis of objective indices. The syntax and coherence of the productions were evaluated by judges. The comparison of the performances of the controls and schizophrenic patients supports the hypothesis that the latter suffer from a language disorder affecting the oral mode but impacting less frequently and less severely on the written mode. These results are discussed in the light of the cognitive mechanisms which may provide an explanation of these language disorders.

Is there a gender difference in a factorial structure of the positive and negative syndrome scale? A test by structural equation modeling

By means of the multisample structured means strategy, we examined gender differences in a five-factorial structure model of Positive and Negative Syndrome Scale (PANSS) ratings of 308 patients of both sexes with DSM-IV schizophrenia with comparable age at investigation and overall symptomatic severity across sex. The test indicated that the factors and component symptoms were common across sex, whereas the factor loadings might be different. However, the model that incorporated the difference in the factor loadings did not improve model fit indices. Therefore, it is concluded that this investigation elicited only minimal gender differences, and on the whole confirmed the PANSS five-factor structure for both sexes.

Comparison of the continuous performance test with and without working memory demands in healthy controls and patients with schizophrenia

The Penn Continuous Performance Test (PCPT), a measure of sustained visual attention developed for use in functional neuroimaging studies, was compared with a standard CPT developed by Gordon Diagnostic Systems (GDS; Vigilance subtest). The PCPT and the GDS CPT were administered with a standard neuropsychological battery to 68 healthy adults to assess reliability and construct validity. The test had adequate internal consistency, and convergent validity was established through significant correlations between measures of efficiency on the PCPT and the GDS CPT. With the exception of a significant correlation between efficiency measures on the GDS CPT and a measure of auditory sustained attention, neither version of the CPT correlated significantly with other measures in the battery. Factor analysis showed that the PCPT loaded with the GDS CPT. In 39 patients with schizophrenia and 39 matched, healthy controls, equivalent impairment was evident on the two CPT tasks. Neither version correlated significantly with symptom measurements. These results support previous conclusions that sustained visual attention in schizophrenia is a core information processing deficit, not directly related to symptomatology.

Sustained and selective attention as measures of genetic liability to schizophrenia

We tested for a relationship between attention and genetic liability to schizophrenia. Samples of probands with DSM-IV schizophrenia (n=20), their well first-degree relatives (n=40) and healthy controls (n=82) were tested using measures of sustained attention (degraded-stimulus continuous performance test: DS-CPT) and selective attention (spatial negative priming task). Assuming a liability-threshold model, we predicted that probands would display greater attentional decrements than controls and that the relatives would show intermediate levels of decrement. We did not observe the predicted pattern of effect using either measure, although the probands showed a trend towards less negative priming. However, our results may have been affected by self-selection bias in probands and relatives and clinical heterogeneity among probands, which could have reduced our power to detect effects.

Vigilance in schizophrenia and its disruption by impaired pre-attentive selection: a dysintegration hypothesis

INTRODUCTION

The study determined, simultaneously, whether major deficits of schizophrenia (sustained and selective attention, slow information processing, slow motor responding) are independent or related to each other.

METHODS

An auditory vigilance task (Pigache Attention Task, PAT) required a button-press to targets during four 5-minute subtests (slow diotic, fast diotic, slow dichotic, fast dichotic, analogous to four versions of the continuous performance test). Twenty schizophrenics on the first test-occasion of a double-blind, placebo controlled, crossover study were compared to 11 healthy subjects. Also, all 28 fortnightly test occasions were analysed to quantify the schizophrenia deficits more precisely and the PAT was evaluated in a larger group of 86 healthy subjects.

RESULTS

Schizophrenics were significantly impaired on all task parameters versus healthy subjects. The patients' errors were independent and additive (grand mean components: basic task 36%, including a 9% time-on-task component; speed increment 26%; dichotic increment 38%). Errors, latencies, and psychosis severity were mutually correlated.

CONCLUSIONS

The performance of all subjects confirmed a quantitative Vigilance Decision Model. The PAT impairments in schizophrenia suggested that rival options (e.g. thoughts) redeployed or suppressed attention away from the task , indicating a dysfunction of pre-attentive selection processes. Brain mechanisms are discussed and a new dys integration hypothesis of schizophrenia is proposed.

Event-related potentials in schizophrenic patients during a degraded stimulus version of the visual continuous performance task

Previous studies of the auditory P300 event-related potential (ERP) have reported smaller amplitudes in chronic schizophrenics but similar consistencies have not been observed with visual P300s. This study examined P300s in symptomatically stable, medicated, chronic schizophrenics (n = 14) and normal controls (n = 14) performing a visual continuous performance task utilizing degraded stimuli to burden encoding processes. Performance analysis found slower response times, fewer target detections and more false alarms in patients than in controls. Analysis of ERPs showed P300 amplitudes of schizophrenics to be significantly smaller than those of controls and, unlike controls, schizophrenics failed to exhibit significant target vs. non-target P300 amplitude differences. Discriminant analysis indicated target and non-target midline (Fz, Cz, Pz) P300 amplitudes together correctly classified all patients and controls. Exploratory topographic analysis indicated that P300 amplitudes were not asymmetrical in patients, as has been observed with auditory P300s, and, unlike the performance measures, the P300s did not correlate with the patient's positive or negative symptom ratings. The implications of these findings are described in relation to attentional disturbances and trait versus state issues in schizophrenics.

Symptom correlates of attentional improvement following hospitalization for a first episode of affective psychosis

BACKGROUND

This study examined patients with a first-episode of affective psychosis during acute and compensated states in order to determine whether changes in attentional functioning over time were accompanied by changes in the severity of psychotic or affective symptoms.

METHODS

Attentional performance was measured in patients (n = 27) using the degraded-stimulus continuous Performance Test (CPT) and symptoms were assessed at the time of index hospitalization, and 2 months after discharge. A comparison group of normal volunteers (n = 31) also performed the CPT two months apart.

RESULTS

Patients performed significantly worse than controls at the initial testing but not at follow-up. The improvement in attentional performance significantly correlated with decreased severity of manic symptoms.

CONCLUSIONS

Results suggest attentional dysfunction is a state-dependent characteristic of mania, and may provide an additional measure of clinical improvement following treatment.

Neuropsychological correlates of negative, disorganized and psychotic symptoms in schizophrenia

Recent studies suggest that three dimensions (negative, disorganized and psychotic) categorize schizophrenic symptoms. A developing literature indicates distinct cerebral correlates of each symptom cluster, but few investigations have determined their neuropsychological correlates. In the present study, the Schedules of Negative and Positive Symptoms measured symptom severity in 62 schizophrenics, and a subsequent principal components analysis revealed three symptom dimensions. Factor scores, age and parental socio-economic status were simultaneously entered into regression equations to explain variance across a broad neuropsychological test battery. Negative symptoms were associated with deficits involving intelligence, executive function, memory, sustained-attention and sensory-motor function, whereas disorganized symptoms correlated with decreased intelligence, attention-span and sensory-motor function. Psychotic symptoms were unrelated to deficits. These data are consistent with hypotheses that these three symptom dimensions have distinct neurobehavioral correlates.

Attention and clinical symptoms in schizophrenia

Attentional deficits, long established to characterize patients with schizophrenia spectrum disorders, have traditionally been regarded as part of the disorder's clinical syndrome. In this paper we provide evidence to indicate that: a) impaired attention is a dimension of schizophrenia that is independent of clinical state, and b) that attention does not appear to respond to the medication (i.e. standard neuroleptics) most typically used to treat clinical symptoms. Since intact attention and other cognitive processes appear critical to successful functioning in the community after hospital discharge, these findings have major implications for treatment.

The categorization of thought disorder

We describe the development of a new system for categorizing thought disorder. In the development phase (Study 1), we examined the degree to which speech samples and definitions of thought disorder subtypes taken from: (1) the Scale for the Assessment of Thought, Language, and Communication (TLC); (2) the Thought Disorder Index (TDI); and (3) the Assessment of Bizarre-Idiosyncratic Thinking (BIT), reflected disturbances in form versus disturbances in content. Ratings were provided by naive judges, experienced clinicians, and linguistic experts. The results contributed to the development of a new system dividing thought disorder into disturbances in (1) fluency, (2) discourse coherence, (3) content, and (4) social convention. In the validation phase (Study 2), 21 schizophrenic and 19 manic subjects were interviewed, interpreted proverbs, and responded to Rorschach cards. Subjects' speech was rated using the TLC, TDI, and BIT. We also measured hallucinations, delusions, and digit span performance. The results of Study 2 provided evidence supporting the validity of our new categorization system.

Slow-wave sleep and symptomatology in schizophrenia and related psychotic disorders

Deficits in slow-wave sleep (SWS), or delta sleep, are frequently seen in schizophrenia, but their relationship with schizophrenic symptomatology remains unclear. We examined the association between visually scored and automated measures of SWS and positive and negative symptoms in a series of unmedicated patients with schizophrenia and related psychotic disorders. Total and average automated delta wave counts were significantly inversely associated with negative symptoms overall, and the psychomotor poverty syndrome in particular. Total delta counts were also inversely related to the disorganization syndrome. No relation was seen between reality distortion or the Brief Psychiatric Rating Scale (BPRS) positive symptoms and SWS. These findings support the view that SWS deficits may be related to negative symptoms of schizophrenia and may perhaps be mediated by impaired functioning of frontothalamic neural circuits.