Stability of cognitive functioning early in the course of schizophrenia

Schizophrenia: Communication Disorders and Role of the Speech-Language Pathologist

PURPOSE

This clinical focus article aims to provide a comprehensive overview of schizophrenia and understanding of communication disorders resulting from its psychopathology. Schizophrenia is a spectrum disorder with varying levels of symptom expression. It is characterized by positive and negative symptoms that can cause communication disorders of different severity levels. Communication difficulties manifest as a range of symptoms such as alogia, disorganized speech, and impaired social communication. These challenges may result in receptive and expressive language deficits that lead to misunderstandings, reduced social interactions, and difficulties expressing thoughts and emotions effectively. The purpose of this clinical focus article is to explore the role of the speech-language pathologist (SLP) in assessing and treating communication disorders presented in schizophrenia.

CONCLUSIONS

In order to understand the role of the SLP in assessing and treating communication disorders in schizophrenia, it is imperative to understand the overall course, etiology, assessment, and treatment consideration of this condition. SLPs can provide services in the areas of social skills training and community-based intervention contexts.

Cognitive trajectories following onset of psychosis: a meta-analysis

BACKGROUND

Cognitive impairment is a core feature of schizophrenia, associated with poor functional outcomes. The course of cognitive function in the years following illness onset has remained a subject of debate, with a previous analysis finding no worsening, providing support for the neurodevelopmental model of schizophrenia. Since then, many more studies have reported on longitudinal cognitive performance in early psychosis, with some indicating deterioration, which does not align with this view.

AIMS

This study aims to quantitatively review the literature on the longitudinal trajectory of cognitive deficits in the years following psychosis onset, in comparison with healthy controls. It is the first to also synthesise longitudinal data on social cognition.

METHOD

Electronic databases ('PubMed', 'PsycInfo' and 'Scopus') were searched (to end September 2021). Meta-analyses of 25 longitudinal studies of cognition in early psychosis were conducted (1480 patients, 789 health controls). Unlike previous analyses, randomised controlled trials and those with multiple cognitive testing periods within the first year were excluded to minimise bias (PROSPERO, ID: CRD42021241525).

RESULTS

Small improvements were observed for global cognition (g = 0.25, 95% CI 0.17-0.33) and individual cognitive domains, but these were comparable with healthy controls and likely an artefact of practice effects.

CONCLUSIONS

There is no evidence of continued cognitive decline or improvement in the early years following psychosis onset, with a need for more studies over longer follow-up periods. Practice effects highlight the importance of including control samples in longitudinal and intervention studies. Further data are needed to evaluate the course of social cognition subdomains.

High-intensity interval training and active video gaming improve neurocognition in schizophrenia: a randomized controlled trial

There is a need for treatments targeting neurocognitive dysfunctions in schizophrenia. The aim of this study was to investigate the neurocognitive effect of aerobic high-intensity interval training (HIIT). A comparison group performed sport simulating active video gaming (AVG). We anticipated that HIIT would improve neurocognition beyond any effect of AVG, due to engagement in higher intensity cardiorespiratory demands. Recent research on the beneficial neurocognitive effect of AVG challenges this expectation but added new relevance to comparing the two interventions. This is an observer-blinded randomized controlled trial. Eighty-two outpatients diagnosed with schizophrenia were allocated to HIIT (n = 43) or AVG (n = 39). Both groups received two supervised sessions per week for 12 weeks. The attrition rate was 31%, and 65% of the participants were defined as protocol compliant study completers. Intention-to-treat analyses showed significant improvements in the neurocognitive composite score from baseline to post-intervention and from baseline to 4 months follow-up in the total sample. The same pattern of results was found in several subdomains. Contrary to our hypothesis, we found no interaction effects of time and group, indicating equal effects in both groups. Separate within-group analysis unexpectedly showed trends of differential effects in the learning domain, as HIIT showed post-intervention improvement in verbal but not visual learning, while AVG showed improvement in visual but not verbal learning. HIIT and AVG improve neurocognition equally, suggesting that both interventions may be applied to target neurocognition in schizophrenia. Future research should investigate trends towards possible differential effects of exercise modes on neurocognitive subdomains. NCT02205684, 31.07.14.

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.

Associations between C-reactive protein levels and cognition during the first 6 months after acute psychosis

OBJECTIVE

Inverse relationships between the C-reactive protein (CRP) levels and cognitive performance in acute psychosis have been demonstrated. We aimed to investigate how the serum level and initial change of CRP in acutely admitted patients with psychosis was correlated with cognitive performance during a 6-months follow-up period.

METHODS

The study is part of a pragmatic, randomised trial comparing four different second-generation antipsychotic drugs, and consists of 208 acute phase patients recruited at admittance for psychosis. This study reports data for all groups collectively, and does not compare treatment groups. Measurements of CRP and cognitive performance were conducted at baseline (T1) and after 4 weeks on average after inclusion (T2). Cognition was also assessed after 3 months (T3) and 6 months (T4) of follow-up.

RESULTS

Global cognition improved during the follow-up period of 6 months, especially in the T1-T2 interval. The different cognitive subdomains showed different time-dependent profiles of improvement, with memory and attention improving significantly also in the later phases. Reduction of the CRP level during the initial follow-up interval (T1-T2) was associated with increased overall cognitive performance in the T2-T4 interval, but not in the T1-T2 interval. For the cognitive subdomains, we found an inverse association between change in CRP level and verbal abilities (T2-T4 interval), and attention (T2-T3 interval).

CONCLUSION

These findings indicate that initial changes in the serum level of CRP in the acute phase of psychosis may predict cognitive function in later phases of the disease.

Longitudinal stability of cognitive control in early psychosis: Nondegenerative deficits across diagnoses

Cognitive impairment, particularly in the domain of cognitive control, is characteristic of schizophrenia (SZ) spectrum and bipolar disorders (BDs). The longitudinal trajectory of these impairments, however, remains unclear. Indeed, some studies have observed degeneration and others stability or even improvement over time in these illnesses. Here we examined the longitudinal stability of the AX-Continuous Performance Task (AX-CPT), a cognitive control task, in 52 patients with recent-onset SZ (<2 years from first study measurement), 20 patients with recent-onset BD Type I with psychotic features, and 70 healthy control subjects. Subjects performed the AX-CPT at 2 time points separated by an average of 365 days (range 270-620). Previously identified deficits in cognitive control were replicated in both patient groups. No effects of time or interactions between time and diagnosis were observed. Intraclass correlation coefficients also suggested AX-CPT performance was stable across time for all diagnostic groups. Although performance was stable on average, a positive association was noted between change in cognitive control and change in disorganization symptom severity across patient groups. In conclusion, the present findings suggest that deficits in cognitive control are present in both disorders and stable over the early course of psychotic illness. No evidence was observed for progression or deterioration of cognitive control or differential recovery in SZ compared to BD. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Clinical symptoms predict concurrent social and global functioning in an early psychosis sample

AIM

Although well established in chronic schizophrenia, the key determinants of functioning remain unknown during the early phase of a psychotic disorder. The aim of this study was to comprehensively examine the social cognitive, basic neurocognitive and clinical predictors of concurrent social functioning and global functioning in an early psychosis sample.

METHODS

This study examined the relationship between social cognition, basic neurocognition and clinical symptoms with concurrent functioning in 51 early psychosis individuals. Assessments included a range of self-report, observational and clinician-rated measures of cognitive, symptom severity and functioning domains.

RESULTS

Results revealed a significant association between self-reported social function and lower levels of both social interaction anxiety and negative psychotic symptoms. A significant association was also observed between lower levels of negative psychotic symptoms and observed social functioning. Lastly, results demonstrated a significant association between reduced negative psychotic symptoms and clinician-rated global functioning.

CONCLUSIONS

Clinical domains such as negative symptoms and social interaction anxiety significantly contribute to an optimal model predicting outcome during the early phase of a psychotic disorder. These clinical features may also provide useful markers of an individual's capacity for social participation. Clinical implications include the need for early targeted intervention to address social anxiety and negative psychotic symptoms to facilitate optimum patient outcome.

Measuring stability of cognitive impairment in inpatients with schizophrenia with alternate forms of the Montreal Cognitive Assessment during acute hospitalization

Cognitive impairment is a core feature of schizophrenia. Measuring the stability of cognitive impairment is important for further understanding of this disorder. The Montreal Cognitive Assessment (MoCA) has been demonstrated to be a brief and effective screening tool in detecting cognitive impairment in patients with schizophrenia. It has alternative versions designed for longitudinal settings. The current study retrospectively analyzed the total and subscores of two versions of the MoCA, administered to a group of inpatients with severe schizophrenia at admission and discharge, to measure their cognitive stability during hospitalization. The results revealed that the test-retest reliability coefficient of the MoCA had good reliability, suggesting the two alternative versions of the MoCA are reliable measurements for assessing cognitive impairment repeatedly in patients with schizophrenia. The paired-samples t-test showed that the overall cognitive impairment of patients measured by two forms of the MoCA remained stable during acute hospital stay and across symptom changes. Furthermore, the results showed that patients' cognitive stability was not related to their symptom/illness severity improvement, age, education, or length of stay.

The course of cognitive functioning after first-episode of psychosis: A six month follow-up study

Our aim with the present study was to evaluate rank-order and mean-level cognitive functioning stability among first-episode psychosis (FEP) patients, measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB), over a six month period. We also aimed to examine longitudinal measurement invariance and identify factors-such as age, gender, educational level, treatment and psychopathological change scores-potentially linked to cognitive change among patients. In addition, correlations between objectively measured and subjectively evaluated cognitive functioning were estimated. Neuropsychological assessments were administered to 85 patients after the initial stabilisation of their psychosis; 82 of the patients were retested. Subjectively perceived cognitive functioning was measured using a subscale derived from the Estonian version of the Subjective Well-Being Under Neuroleptic Scale (SWN-K-E). On average, executive functioning and processing speed improved significantly, while memory test scores decreased significantly, over time. Very high rank-order stability (r=0.80 to 0.94, p<0.001) was observed with all measured ability scores. Confirmatory factor analysis revealed the loadings of a single (broad ability) factor model were equal across both measurement occasions, but the lack of intercept invariance suggested that mean-level comparisons are more appropriately carried out at a subtest level. On average psychopathology scores and antipsychotics doses declined over time, with the latter also significantly correlating with better executive functioning. Gender was a significant moderator of some domains of cognitive performance, and decline tended to be somewhat more pronounced for women. The results also indicated the lack of any relationship between objective and subjective measurements of cognitive functioning.

Performance in multiple domains of social cognition in parents of patients with schizophrenia

Social cognition refers to a set of cognitive abilities that allow us to perceive and interpret social stimuli. Social cognition is affected in schizophrenia and impairments have also been documented in unaffected relatives, suggesting that social cognition may be related to a genetic vulnerability to the disease. This study aims to investigate potential impairments in four domains of social cognition (mentalizing, emotion recognition, social knowledge and empathy) in the same group of relatives in order to gather a more complete picture of social cognition difficulties in this population. The Batterie Intégrée de Cognition Sociale (BICS) (mentalizing, emotion recognition, and social knowledge) and the Interpersonal Reactivity Index (IRI) (empathy) were administered to 31 parents of patients with a psychotic disorder and 38 healthy controls. Parents of patients performed significantly worse than controls on the mentalizing test but significantly better on the social knowledge test. No significant between-group differences were observed for emotion recognition and empathy. This study is the first to evaluate four social cognition domains in this population. The results precise which social cognition processes may be impaired or preserved in unaffected relatives of patients and lead us to propose an hypothesis about a mechanism that could underlie the mentalizing difficulties observed in this population.

Meta-analysis of cognitive deficits in ultra-high risk to psychosis and first-episode psychosis: do the cognitive deficits progress over, or after, the onset of psychosis?

Cognitive dysfunction is a well-established feature of schizophrenia, and there is evidence suggesting that cognitive deficits are secondary to abnormal neurodevelopment leading to problems in acquiring such abilities. However, it is not clear whether there is also a decline in cognitive performance over, or after, the onset of psychosis. Our objective was to quantitatively examine the longitudinal changes in cognitive function in patients who presented with first-episode psychosis (FEP), ultra-high risk (UHR) for psychosis, and controls. Electronic databases were searched for the studies published between January 1987 and February 2013. All studies reporting longitudinal cognitive data in FEP and UHR subjects were retrieved. We conducted meta-analyses of 25 studies including 905 patients with FEP, 560 patients at UHR, and 405 healthy controls. The cognitive performances of FEP, UHR, and healthy controls all significantly improved over time. There was no publication bias, and distributions of effect sizes were very homogenous. In FEP, the degree of improvement in verbal working memory and executive functions was significantly associated with reduction in negative symptoms. There was no evidence of cognitive decline in patients with UHR and FEP. In contrast, the cognitive performances of both groups improved at follow-up. These findings suggest that cognitive deficits are already established before the prodromal phases of psychosis. These data support the neurodevelopmental model rather than neurodegenerative and related staging models of schizophrenia.

Developing a Cognitive Training Strategy for First-Episode Schizophrenia: Integrating Bottom-Up and Top-Down Approaches

It is clear that people with schizophrenia typically have cognitive problems in multiple domains as part of their illness. The cognitive deficits are among the main contributors to limitations in their everyday functioning, including their work recovery. Cognitive remediation has been applied successfully to help people with long-term, persistent schizophrenia to improve their cognitive functioning, but it is only beginning to be applied with individuals who have recently had a first episode of psychosis. Several different approaches to cognitive training have been developed. Some approaches emphasize extensive systematic practice with lower-level cognitive processes and building toward higher-level processes ("bottom-up"), while others emphasize greater focus on high-level cognitive processes that normally integrate and organize lower-level processes ("top-down"). Each approach has advantages and disadvantages for a disorder like schizophrenia, with its multiple levels of cognitive dysfunction. In addition, approaches to cognitive remediation differ in the extent to which they systematically facilitate transfer of learning to everyday functioning. We describe in this article the cognitive training approach that was developed for a UCLA study of people with a recent first episode of schizophrenia, a group that may benefit greatly from early intervention that focuses on cognition and recovery of work functioning. This approach integrated bottom-up and top-down computerized cognitive training and incorporated an additional weekly group session to bridge between computerized training and application to everyday work and school functioning.

Changes in aspects of cognitive functioning in young patients with schizophrenia during group psychodynamic psychotherapy: a preliminary study

BACKGROUND

The "Sveti Ivan" psychiatric hospital in Zagreb, Croatia, offers an outpatient Early Intervention Program for psychotic patients. This program consists of psycho-educational workshops and group psychodynamic psychotherapy. Two important objectives of the program are improving and maintaining adequate cognitive functioning.

AIMS

The current study examined changes in aspects of cognitive functioning in young patients with schizophrenia after 18 months and after 3 years of psychodynamic group psychotherapy.

METHODS

The study included 28 patients who attended the Early Intervention Program for young patients with psychotic disorders; 10 patients had completed only the psycho-educational part of the program (comparative group), and 18 patients continued with group psychodynamic psychotherapy (experimental group). All patients completed the Revised Beta Examination.

RESULTS

We observed a trend in the experimental group to achieve higher scores than the comparative group. The results for both groups tended to increase with time, and this increase was greater in the experimental group.

CONCLUSIONS

While acknowledging the limitations of this preliminary study, we conclude that participating in psychodynamic group psychotherapy is related to increases in the cognitive functioning of patients with schizophrenia, and our results provide a sound basis for future research.

Quetiapine and flupentixol differentially improve anterior cingulate cortex function in schizophrenia patients: an event-related potential study

Atypical antipsychotic agents are a frequently and effectively used treatment in schizophrenia and psychotic disorders. Other than conventional antipsychotics, which mainly exert their pharmacological effect in subcortical dopaminergic systems, atypical antipsychotics additionally affect partly serotonergically innervated structures within prefrontal areas, such as the anterior cingulate cortex (ACC). However, only few controlled, randomized studies have so far investigated direct and indirect effects of atypical antipsychotics on the ACC and, up until now, no clinical investigation has exclusively addressed the specific effects of quetiapine on ACC function. The present study assessed ACC function in 18 quetiapine-medicated patients and 13 flupentixol-treated patients suffering from schizophrenia by means of the error-related negativity (ERN), a neurophysiological marker of ACC function, in a pre-post design. Between-group comparisons revealed different effects of quetiapine and flupentixol on ACC function despite similar improvement in psychopathology, cognitive performance and quality of life. Whereas atypical treatment was associated with an increase in amplitudes over time, there were prolonged ERN peak latencies in patients treated with the typical agent. Moreover, treatment effects depended on baseline prefrontal cortex function in both groups. We conclude that both flupentixol and quetiapine improve prefrontal function especially in patients with weak initial ACC function which might be due to their shared affinity for serotonin receptors in frontal brain regions. However, since this affinity is more pronounced for quetiapine, patients treated with quetiapine seemed to profit more evidently concerning their prefrontal cortex function compared to patients of the flupentixol group, who exhibited a compensatory prolongation of processes.

Neurocognitive predictors of work outcome in recent-onset schizophrenia

While the role of neurocognitive impairment in predicting functional outcome in chronic schizophrenia is now widely accepted, the results that have examined this relationship in the early phase of psychosis are surprisingly rather mixed. The predictive role of cognitive impairment early in the illness is of particular interest because interventions during this initial period may help to prevent the development of chronic disability. In a University of California, Los Angeles (UCLA) longitudinal study, we assessed schizophrenia patients with a recent first episode of psychosis using a neurocognitive battery at an initial clinically stabilized outpatient point and then followed them during continuous treatment over the next 9 months. Three orthogonal cognitive factors were derived through principal components analysis: working memory, attention and early perceptual processing, and verbal memory and processing speed. All patients were provided a combination of maintenance antipsychotic medication, case management, group skills training, and family education in a UCLA research clinic. A modified version of the Social Adjustment Scale was used to assess work outcome. Multiple regression analyses indicate that the combination of the 3 neurocognitive factors predicts 52% of the variance in return to work or school by 9 months after outpatient clinical stabilization. These data strongly support the critical role of neurocognitive factors in recovery of work functioning after an onset of schizophrenia. Cognitive remediation and other interventions targeting these early cognitive deficits are of major importance to attempts to prevent chronic disability.

Cognition at illness onset as a predictor of later functional outcome in early psychosis: systematic review and methodological critique

BACKGROUND

Cognitive deficits occur early in the course of psychosis, are mostly stable, and have been identified as potential functional prognostic markers. Previous reviews of chronic schizophrenia have concluded that specific cognitive deficits are strongly associated with poorer functional outcomes. However, results of schizophrenia studies may be influenced by the effects of long-term illness or treatment or be biased toward individuals with poorer outcomes and may not be relevant to early psychosis (EP). This review aimed to systematically examine the evidence regarding general and social cognitive predictors of later functional outcome in EP and critique the methodology of the studies reviewed. A final aim was to conduct a meta-analysis of the studies reviewed, but methodological reasons precluded this.

METHOD

A comprehensive search of PsycINFO and MEDLINE databases identified 15 relevant articles and 7 further articles following a reference list search, totaling 22 included articles.

RESULTS

Most studies found at least one cognitive domain predicted functional outcome, but examination of separate cognitive domains revealed there were more null than significant associations between cognition and functional outcome across every cognitive domain. No study examined social cognition as a predictor of outcome. The frequency with which different cognitive domains predicted outcome varied depending on study methodology and this was most noticeable when studies with short-term follow-up were compared with longer-term follow-up studies.

CONCLUSIONS

Due to the methodological variability and limitations of the studies reviewed, firm conclusions regarding the relationship between cognition and functional outcomes in EP cannot be made. Tentatively, cognition may be prognostic in EP, especially for longer-term outcomes. However, further research that addresses the methodological issues identified, including examination of social cognition and other non-cognitive predictors, is needed.

Longitudinal studies of cognition in first episode psychosis: a systematic review of the literature

Although cognitive deficits are recognized as a core feature in schizophrenia, their evolution over the course of the illness is still debated. Longitudinal studies of cognition in patients after a first episode of psychosis (FEP) provide extremely useful information, in that they include an adequate and realistic baseline measure of cognitive performance, while at the same time minimizing the effect of confounding variables associated with chronicity. The aim of this systematic review was to summarize findings of studies assessing the longitudinal course of neuropsychological deficits in patients with FEP for durations of at least one year. Overall, the neuropsychological deficits that are present following a first episode of psychosis appeared to remain stable over time for periods of up to ten years, the only possible exception being verbal memory deficits, where there is some evidence of further deterioration over the long term. However, further studies are needed to confirm this conclusion, especially in the (somewhat inconsistently defined) domain of executive function. Improvements in psychopathology appear to positively influence the course of cognitive deficits, although the effects of antipsychotic medication are not as clear.

Cognitive functioning in subjects with recent-onset psychosis from a low-middle-income environment: multiple-domain deficits and longitudinal evaluation

Cognitive deficits are a key feature of recent-onset psychosis, but there is no consensus on whether such deficits are generalized or confined to specific domains. Besides, it is unclear whether cognitive deficits: a) are found in psychotic patients in samples from outside high-income countries; and b) whether they progress uniformly over time in schizophrenia and affective psychoses. We applied 12 tests organized into eight cognitive domains, comparing psychosis patients (n = 56, time from initial contact = 677.95+/-183.27 days) versus healthy controls (n=70) recruited from the same area of São Paulo, Brazil. Longitudinal comparisons (digit span and verbal fluency) were conducted between a previous assessment of the subjects carried out at their psychosis onset, and the current follow-up evaluation. Psychosis patients differed significantly from controls on five domains, most prominently on verbal memory. Cognitive deficits remained detectable in separate comparisons of the schizophrenia subgroup and, to a lesser extent, the affective psychosis subjects against controls. Longitudinal comparisons indicated significant improvement in schizophrenia, affective psychoses, and control subjects, with no significant group-by-time interactions. Our results reinforce the view that there are generalized cognitive deficits in association with recent-onset psychoses, particularly of non-affective nature, which persist over time.

Effects of add-on mirtazapine on neurocognition in schizophrenia: a double-blind, randomized, placebo-controlled study

Mirtazapine added to antipsychotics appears to improve the clinical picture of schizophrenia, including both negative and positive symptoms. This study explored the effect of adjunctive mirtazapine on neurocognition in patients with schizophrenia who had shown an insufficient response to first-generation antipsychotics (FGAs). Thirty-seven schizophrenia patients, who were at least moderately ill despite their FGA treatment, received add-on mirtazapine (n=19) or placebo (n=18) in a 6-wk double-blind, randomized trial. Widely used neuropsychological tests were performed to explore visual-spatial functions, verbal and visual memory, executive functions, verbal fluency and general mental and psychomotor speed. The data were analysed on the modified intent-to-treat basis with last observation carried forward. False discovery rate was applied to correct for multiple testing. Mirtazapine outperformed placebo in the domains of visual-spatial ability and general mental speed/attentional control as assessed by, correspondingly, Block Design and Stroop dots. The difference in the degree of change (i.e. change while on mirtazapine minus that on placebo) was 18.6% (p=0.044) and 11.1% (p=0.044), respectively. Adjunctive mirtazapine might offer a safe, effective and cost-saving option as a neurocognitive enhancer for FGA-treated schizophrenia patients. Mirtazapine+FGA combinations may become especially useful in light of the currently increasing attention towards FGAs. Larger and longer studies that incorporate functional outcomes, as well as comparisons with second-generation antipsychotics are, however, still needed for more definite conclusions.

Course of neurocognitive deficits in the prodrome and first episode of schizophrenia

Understanding the trajectory of cognitive changes in the development of schizophrenia may shed light on the neurodevelopmental processes in the beginning stage of illness. Subjects at risk for psychosis (AR, n = 48), patients in their first episode of schizophrenia (FE, n = 20), and normal comparison subjects (n = 29) were assessed on a neurocognitive battery at baseline and at a 6-month follow-up. There were significant group differences across all cognitive domains as well as a significant group by time interaction in the verbal learning domain. After statistically controlling for practice effects and regression to the mean, a high proportion of FE subjects showed an improvement in verbal learning, and a significant number of AR subjects improved in general intelligence. Moreover, a higher than expected percentage of FE subjects, as well as AR subjects who later converted to psychosis, showed a deterioration in working memory and processing speed. These inconsistent trajectories suggest that some domains may improve with stabilization in the early stages of psychosis, whereas others may decline with progression of the illness, indicating possible targets for cognitive remediation strategies and candidate vulnerability markers for future psychosis.

Cognitive markers of short-term clinical outcome in first-episode psychosis

BACKGROUND

Outcome from psychotic disorders is heterogeneous with poorer outcomes frequently identified too late to be influenced. Symptomatic ratings at 1 or more years following initiation of treatment have been related to cognition in first-episode psychosis. However, the relationship between cognition and early outcome remains unclear.

AIMS

To determine whether specific cognitive domains could identify poor short-term outcome among individuals with first-episode psychosis.

METHOD

One hundred and fifty-one individuals with first-episode psychosis were divided into two groups based on 6-month clinical data after the initiation of treatment. Six cognitive domains were compared among 78 participants with poor outcomes, 73 with good outcomes and 31 healthy controls.

RESULTS

Lower performance on verbal memory (z-scores: poor outcome=-1.3 (s.d.=1.1); good outcome=-0.8 (s.d.=0.9); P=0.001) and working memory (poor outcome=-1.0 (s.d.=1.2); good outcome=-0.4 (s.d.=0.9); P=0.003) identified individuals with first-episode psychosis with a poor outcome after 6 months of treatment.

CONCLUSIONS

The early identification of those individuals with first-episode psychosis with a poor clinical outcome may encourage clinicians to pay special attention to them in the form of alternative pharmacological and psychological treatments for a more favourable outcome in the long term.

1-year follow-up study of cognitive function in first-episode non-affective psychosis

The longitudinal course of primary cognitive dysfunction seen in schizophrenia has yet to be fully clarified. Whereas some studies in chronic patients have revealed a progressive decline in cognitive abilities, those studies with first-episode patients have indicated that initial cognitive deficits might remain stable over time. The aim of this study was to examine the longitudinal course of cognitive functioning in patients with a first episode of schizophrenia. 112 patients with a first episode of schizophrenia-spectrum disorders and 22 healthy controls completed clinical and cognitive evaluations at baseline and again after 1 year. An extensive neuropsychological battery that comprised seven cognitive domains was used. Patients and controls improved their cognitive performance in virtually all the cognitive domains after one year. However, patients continued to show marked cognitive deficits after one year, unlike healthy volunteers. The longitudinal cognitive changes were similar in patients and controls in all domains except Verbal Memory (F = 11.67; df = 1; P = 0.001). The increase in cognitive scores found during early phases of the illness seems to be associated to practice-related changes and would not reflect a real cognitive enhancement but rather stability of deficit. Patients' deficits remained stable over time in all cognitive domains except Verbal Memory, in which less performance improvement was found. Further investigations are warranted to discern the variability in patterns of specific cognitive deficits over time.

Cognitive factors for predicting treatment response in schizophrenic patients: one-year follow-up study

OBJECTIVE

This study was conducted to investigate the cognitive factors that can longitudinally predict the response to treatment in patients with schizophrenia.

METHODS

The subjects were 49 patients with schizophrenia who were newly hospitalized in an acute psychiatry ward and had not been treated with medication for at least 8 weeks prior to the study. The symptoms and cognitive functions of the patients were evaluated at baseline before treatment (T0), at eight weeks after treatment (T1), and one year after treatment (T2). Clinical symptoms were assessed using the PANSS, and cognitive functions were estimated using the Vigilance Test, Cognitrone Test, Wisconsin Card Sorting Test (WCST), and the Korean version of the Memory Assessment Scales (K-MAS).

RESULTS

The patient group showed marked impairments in cognitive function when compared to the normal group, but the patients' clinical symptoms and cognitive functions improved after drug treatment. The patients also showed consistent improvement in verbal and nonverbal memory function as time progressed. Furthermore, there was a significant correlation between clinical symptoms and cognitive functions in the patient group. The cognitive variables that best predicted treatment response and prognosis were total errors on the WCST and immediate list recall component of the K-MAS. It was also shown that the number of total errors on the WCST was a better cognitive predictor than the number of errors in immediate recall.

CONCLUSION

The results of the present study show that the neurocognitive functions of patients with schizophrenia can be stabilized with treatment intervention, that treatment response is related to improvement in cognitive function, and that cognitive domains, especially executive function, can predict treatment response and prognosis in patients with schizophrenia.

Longitudinal studies of cognition in schizophrenia: meta-analysis

BACKGROUND

A wide range of cognitive deficits have been demonstrated in schizophrenia, but their longitudinal course remains unclear.

AIMS

To bring together all the available information from longitudinal studies of cognitive performance in people with schizophrenia.

METHOD

We carried out a meta-analysis of 53 studies. Unlike previous reviewers, we included all studies (regardless of the type of medication), analysed each variable separately and compared results with data from controls.

RESULTS

Participants with schizophrenia showed a significant improvement in most cognitive tasks. The available data for controls showed, with one exception (the Stroop test), a similar or greater improvement. Performance in semantic verbal fluency remained stable in both individuals with schizophrenia and controls.

CONCLUSIONS

Participants with schizophrenia displayed improvement in most cognitive tasks, but practice was more likely than cognitive remediation to account for most of the improvements observed. Semantic verbal fluency may be the best candidate cognitive endophenotype.

Course of cognitive functioning during the stabilization phase of schizophrenia

The present study aimed at examining the longitudinal course of neuropsychological impairments in schizophrenia patients during the stabilization phase of the illness. Cognitive functioning of 151 schizophrenia patients was assessed at baseline, 9-month, and 15-month follow-up with a comprehensive battery of cognitive tests. Cognitive performance of 40 matched controls was also examined at baseline and follow-up in order to control for effects of repeated testing. We found significant improvements in memory, attention, and global cognitive functioning from baseline to 9-month follow-up. Abstraction was stable at a relatively normal level. Global cognitive functioning remained at 9-month follow-up one standard deviation below normative level. Improvements in patients' cognitive performance between the 9-month and the 15-month follow-up were fewer and less pronounced. The present study implies that schizophrenia is a static encephalopathy with trait and state dependent cognitive components particularly in the attention and memory domain. The statistically and clinically significant cognitive improvements should be ground for clinical optimism.

Neurophysiological characteristics of cognitive functions in patients with first episodes of endogenous psychosis

This report presents studies of the neurophysiological correlates of the characteristics of cognitive disorders in patients with first psychotic episodes of endogenous psychosis at juvenile age. Three groups of patients were studied: those with a predominance of catatonic symptomatology (22 patients), those with a predominance of hallucinatory-delusional symptomatology (22 patients), and those with a predominance of affective-delusional symptomatology (24 patients), along with a group of psychologically healthy subjects (15 subjects). Parameters of auditory evoked potentials were analyzed using the oddball paradigm. The group with a predominance of catatonic disorders showed the greatest differences in the latent periods (LP) of the N200 and P300 components as compared with the other groups; patients with a predominance of hallucinatory-delusional symptomatology showed the most localized anomalies in the latent period of the P300 component; the group of patients dominated by affective-delusional symptomatology showed almost no increase in the latent period of the N200 component, though the extents of anomalies in the N100 component in responses to non-target signals and deviations in the P300 component were more marked than in the other groups. These characteristics of the neurophysiological correlates of cognitive functions in each group of patients supported the significance of evaluating the psychopathological structure of manifest psychotic episodes for determining the clinical typology.

Improvement and decline of cognitive function in schizophrenia over one year: a longitudinal investigation using latent growth modelling

BACKGROUND

Long-term follow-up studies of people with schizophrenia report stability of cognitive performance; less is known about any shorter-term changes in cognitive function.

METHODS

This longitudinal study aimed to establish whether there was stability, improvement or decline in memory and executive functions over four assessments undertaken prospectively in one year. Cognitive performance was assessed during randomized controlled trials of first- and second-generation antipsychotic medication. Analyses used a latent growth modeling approach, so that individuals who missed some testing occasions could be included and trajectories of cognitive change explored despite missing data.

RESULTS

Over the year there was significant decline in spatial recognition but no change in pattern recognition or motor speed. Improvement was seen in planning and spatial working memory tasks; this may reflect improved strategy use with practice. There were significant individual differences in the initial level of performance on all tasks but not in rate of change; the latter may have been due to sample size limitations. Age, sex, premorbid IQ and drug class allocation explained significant variation in level of performance but could not predict change. Patients randomized to first-generation drugs improved more quickly than other groups on the planning task.

CONCLUSION

We conclude that cognitive change is present in schizophrenia but the magnitude of change is small when compared with the large differences in cognitive function that exist between patients. Analyses that retain patients who drop out of longitudinal studies, as well as those who complete testing protocols, are important to our understanding of cognition in schizophrenia.

Effects of acute antipsychotic treatment on brain activation in first episode psychosis: an fMRI study

This study aimed to assess the neurophysiological effects of acute atypical antipsychotic treatment on cognitive functioning in subjects presenting with a first episode of psychosis. We used functional MRI to examine the modulatory effects of acute psychopharmacological intervention on brain activation during four different cognitive tasks: overt verbal fluency, random movement generation, n-back and a spatial object memory task. Treatment with atypical antipsychotics was associated with alterations in regional activation during each task and also when task demands were manipulated within paradigms. The initial treatment of psychosis with atypical antipsychotics thus appears to be associated with modifications of the neurofunctional correlates of executive and mnemonic functions. These effects need to be considered when interpreting group differences in activation between medicated patients and controls.

Associations between olfactory identification and verbal memory in patients with schizophrenia, first-degree relatives, and non-psychiatric controls

OBJECTIVE

Olfactory identification deficits and verbal memory impairments may represent trait markers for schizophrenia. The aims of this study were to: (1) assess olfactory identification in patients, first-degree relatives, and non-psychiatric controls, (2) determine differences in verbal memory functioning in these three groups, and (3) study correlations between olfactory identification and three specific verbal memory domains.

METHOD

A total of 106 participants-41 patients with schizophrenia or related disorders, 27 relatives, and 38 controls-were assessed with the University of Pennsylvania Smell Identification Test (UPSIT) and the Wechsler Memory Scale-Third Edition. Linear mixed models, accounting for clustering within families and relevant covariates, were used to compare scores across groups and to examine associations between olfactory identification ability and the three verbal memory domains.

RESULTS

A group effect was apparent for all four measures, and relatives scored midway between patients and controls on all three memory domains. UPSIT scores were significantly correlated with all three forms of verbal memory. Age, verbal working memory, and auditory recognition delayed memory were independently predictive of UPSIT scores.

CONCLUSIONS

Impairments in olfactory identification and verbal memory appear to represent two correlated risk markers for schizophrenia, and frontal-temporal deficits likely account for both impairments.

Generalized and specific cognitive performance in clinical high-risk cohorts: a review highlighting potential vulnerability markers for psychosis

Cognitive deficits are a core feature of established psychotic illnesses. However, the association between cognition and emerging psychosis is less understood. While there is some evidence that cognitive deficits are present prior to the onset of psychosis, findings are not consistent. In this article we provide an overview of the more general cognitive findings available from genetic high-risk studies, retrospective studies, and birth cohort studies. We then focus the review on neuropsychological performance in clinically "at-risk" groups. Overall, general cognitive ability as assessed by established batteries appears to remain relatively intact in these ultra-high risk cohorts and is a poor predictor close to illness onset relative to other vulnerability factors. Further decline may occur with illness progression, more consistent with state relative to trait factors. In addition, most established cognitive tasks involve several relatively discrete cognitive subprocesses, where findings from general batteries of subtests may mask specific deficits. In this context, our review suggests that relatively specific olfactory identification and spatial working memory deficits exist prior to illness onset and may be more potent trait markers for psychosis than cognitively dense tasks such as verbal memory. Suggestions for further research address the importance of standardization of inclusion criteria and the maintenance of basic neuropsychological assessment to allow better comparison of findings across centers. Further, in order to better understand the aetiopathology of cognitive dysfunction in psychosis, more experimental, hypothesis-driven measures of discrete cognitive processes are required. Delineation of the relationship between specific cognitive ability and symptoms from data-driven approaches may improve our understanding of the role of cognition during psychosis onset.

Premorbid intellectual functioning and risk of schizophrenia and spectrum disorders

Evidence from longitudinal studies indicates that lower IQ score in childhood and early adolescence increases risk of schizophrenia and schizophrenia spectrum disorders (SSD). This study investigated the association between premorbid IQ and risk of SSD in a population-based cohort of 17-year-old conscripts. Fifty four thousand males assessed by the Israeli Draft Board during two consecutive years were followed by means of the Israeli National Psychiatric Hospitalization Case Registry for up to 11 years. Tests of verbal and non-verbal reasoning, mathematical knowledge and instructions comprehension and several psychosocial variables were recorded by the Draft Board. Risk for SSD increased with decreasing IQ score. Only poorer non-verbal reasoning conferred a significant increased risk for SSD after taking into account general intellectual ability. IQ was not associated with age of onset. These results confirm the importance of low intellectual functioning as a risk factor for SSD. This is unlikely to be due to prodrome.

Cognitive impairment as a risk factor for psychosis

Since the time of Kraepelin and Bleuler, it has been recognized that schizophrenia is associated with a profound and persistent cognitive impairment. This paper reviews the major clinical and epidemiological studies of cognitive functioning in schizophrenia and other psychotic disorders, and presents several possible models to explain the association between cognitive impairment and psychosis. Cognitive impairment is present in the majority of patients with schizophrenia, and, in some, it is already evident in the premorbid stages of the disorder. This cognitive impairment is not secondary to psychotic symptoms, negative symptoms, or socioeconomic status. Cognitive impairment can also be observed in nonpsychotic family members of psychotic patients. On the basis of this evidence, it has been proposed that abnormal cognitive functioning can be considered as a possible causal risk û chosis. Recent studies assessing the relations genetic background, cognition, brain functic ophrenia are presented here as an outline for future research.

Ten year longitudinal study of neuropsychological functioning subsequent to a first episode of schizophrenia

We previously reported relative stability in neuropsychological functions over a 4- to 5-year period after the onset of a first episode of schizophrenia, with patients demonstrating less improvement than controls on some functions [Hoff, A.L., Sakuma, M., Wieneke, M., Horon, R., Kushner, M., DeLisi, L.E., 1999. A longitudinal follow-up study of neuropsychological functioning subsequent to a first-episode of schizophrenia. American Journal of Psychiatry 156, 1336-1341.]. The current study was conducted to extend follow-up evaluations through 10 years of illness to determine whether neuropsychological functions remain stable or deteriorate over a longer time period. Twenty-one first episode patients and 8 controls were re-evaluated 10 years after an initial evaluation on neuropsychological and clinical measures. Repeated measures analyses demonstrated no differences between patients and controls in degree of change over this time period nor was change in symptoms reliably associated with improvement or deterioration in cognitive abilities. However, baseline level of cognitive functioning was correlated with the degree of change. Thus, when the baseline level of functioning was controlled for in the analyses, less or lack of improvement was seen in the patients compared with controls in verbal intellectual functioning, delayed verbal and nonverbal recall, and cognitive inhibition (Stroop Color Word Test). In no test did patients deteriorate significantly more than controls. We conclude that most first episode patients have had considerable cognitive decline by the time of their first hospitalization and that it remains relatively stable through at least 10 years of illness. Most cognitive change takes place early in this illness, prior to the first hospitalization, but its exact timing still remains unknown.

IQ stabilization in childhood-onset schizophrenia

OBJECTIVE

To examine the long term IQ trajectory for childhood-onset schizophrenia (COS) in an expanded, prospective longitudinal study.

METHODS

Seventy children meeting DSM criteria for schizophrenia were tested at 2 year intervals with age appropriate Wechsler intelligence tests and repeated administration of information and comprehension WISC subtests even after age 18. For a subgroup with 31 patients, pre-NIH IQ test administrations were available including 18 pre-psychotic and 13 post-psychotic subjects. The pattern of IQ performance over time was determined using mixed model regression analysis.

RESULTS

No progressive cognitive decline was seen up to 13+ years post psychosis onset. For the subgroup of subjects with pre-illness scores, there had been an initial steep decline in IQ, from about 2 years prior to 1.7 years after onset of psychotic symptoms, as reported for adult patients.

CONCLUSIONS

The level long-term trajectory of IQ measures in COS appears stable, similar to that reported for adult onset patients. For COS, level cognitive functioning extends up to 13+ years post psychosis onset, in spite of chronic illness and concomitant, progressive loss of cortical gray matter.

Cognition in schizophrenia: impairments, determinants, and functional importance

Recent findings support and add to earlier findings of cognitive dysfunction in schizophrenia. Deficits across neurocognitive domains such as attention, working memory, language skills, and executive functioning tend to be moderate, with the most pronounced deficits found in verbal learning and memory. All these neurocognitive domains are related to adaptive and social skills, with executive functions and verbal learning and memory showing more variance across more domains than other neuro-cognitive variables. Negative symptoms and neurocognitive domains, although correlated, are distinct and have differential pathways of change with treatment. General psychopathology symptoms, such as depression and anxiety, may become important treatment targets as strategies are developed for translating cognitive enhancement to real-world functional performance.

A longitudinal analysis of memory in patients with schizophrenia

Memory deficits are widely reported in patients with schizophrenia, but uncertainties remain about the extent and the longitudinal course of these deficits. Twenty-eight patients with a DSM-IV diagnosis of schizophrenia were tested on multiple aspects of memory at baseline, 9- and 18-month follow-up. Measures included: digit span, the Rivermead Behavioural Memory test (RBMT) battery, the Graded Naming Test (GNT) and several computerized memory tests from the Cambridge Automated Neuropsychological Testing Battery (CANTAB). A group of healthy controls (N=17) was tested on the CANTAB battery at baseline and 9-month follow up. The patients performed significantly poorer than controls on all CANTAB measures; however, there was no difference in change between groups over a 9-month period. Within-group patient comparisons revealed that symptoms reduced significantly over the study period, but had no association with memory. Significant improvements were observed for patients on two verbal memory tasks: the GNT and digit span, but not on any other measure. Interestingly, these were the only two tests on which patients were within normal limits at baseline. This study shows that patients with schizophrenia have deficits in multiple aspects of memory which remain stable over long periods of time. In addition, patients showed a tendency to improve on memory tasks which contained a verbal component.

Executive control of working memory in schizophrenia

There is considerable evidence that working memory impairment is a common feature of schizophrenia. The present study assessed working memory and executive function in 54 participants with schizophrenia, and a group of 54 normal controls matched to the patients on age, gender and estimated premorbid IQ, using traditional and newer measures of executive function and two dual tasks-Telephone Search with Counting and the Memory Span and Tracking Task. Results indicated that participants with schizophrenia were significantly impaired on all standardised measures of executive function with the exception of a composite measure of the Trail Making Test. Results for the dual task measures demonstrated that while the participants with schizophrenia were unimpaired on immediate digit span recall over a 2-min period, they recalled fewer digit strings and performed more poorly on a tracking task (box-crossing task) compared with controls. In addition, participants with schizophrenia performed more poorly on the tracking task when they were required to simultaneously recall digits strings than when they performed this task alone. Contrary to expectation, results of the telephone search task under dual conditions were not significantly different between groups. These results may reflect the insufficient complexity of the tone-counting task as an interference task. Overall, the present study showed that participants with schizophrenia appear to have a restricted impairment of their working memory system that is evident in tasks in which the visuospatial sketchpad slave system requires central executive control.

Environmental cognitive remediation in schizophrenia: ethical implications of "smart home" technology

OBJECTIVE

In light of the advent of new technologies, we proposed to reexamine certain challenges posed by cognitive remediation and social reintegration (that is, deinstitutionalization) of patients with severe and persistent mental disorders.

METHOD

We reviewed literature on cognition, remediation, smart homes, as well as on objects and utilities, using medical and computer science electronic library and Internet searches.

RESULTS

These technologies provide solutions for disabled persons with respect to care delivery, workload reduction, and socialization. Examples include home support, video conferencing, remote monitoring of medical parameters through sensors, teledetection of critical situations (for example, a fall or malaise), measures of daily living activities, and help with tasks of daily living. One of the key concepts unifying all these technologies is the health-smart home. We present the notion of the health-smart home in general and then examine it more specifically in relation to schizophrenia.

CONCLUSION

Management of people with schizophrenia with cognitive deficits who are being rehabilitated in the community can be improved with the use of technology; however, such technology has ethical ramifications.

Confusing thoughts and speech: source monitoring and psychosis

To explore the idea that deficits in source monitoring may underlie positive symptoms of schizophrenia, the current study compared schizophrenic patients' performance (n=15) on an internal source-monitoring task with that of normal controls (n=15). On the basis of a source-monitoring task in which participants had to recall whether they had verbalized answers or merely thought about these answers, overall source monitoring performance, discrimination index, and response bias were calculated. In addition, participants completed cognitive tests and symptomatology questionnaires. Relative to controls, patients had significantly more difficulties with monitoring their own actions and showed a tendency towards misclassifying imagined thoughts as verbalized thoughts. Source-monitoring performance was related to selective attention, but not to other cognitive domains. No relationship was found between source-monitoring and symptomatology. Failures in internal source monitoring are a prominent feature of schizophrenia, and our results suggest that they form a more enduring characteristic of this disorder than has previously been assumed.

Secondary verbal memory: a potential endophenotype of schizophrenia

This study aimed at identifying neuropsychological endophenotypes of schizophrenia which met the criteria of stability and sensitivity. Twenty-six non-schizophrenic first-degree relatives together with their affected family members (all simplex-families) underwent assessment with a comprehensive neuropsychological test battery both at baseline and 13 months follow-up. Follow-up patients were in a state of stable remission. Further, 21 unrelated, demographically balanced, non-vulnerable controls were tested one at a time. A principal components analysis of our test battery resulted in four factors: (1) Vigilance, attention, and psychomotor, (2) secondary verbal memory, (3) immediate and working memory, and (3) abstraction and problem solving. At baseline testing our study revealed a pattern of selective cognitive deficits in the relative group that is less pronounced, yet qualitatively similar, to that found in the patient sample. The most severe deficits displayed both the patients and their relatives in the secondary verbal memory domain. The dysfunctions in secondary verbal memory at baseline testing significantly correlated with negative symptoms only. Secondary verbal memory deficits proved to be relatively independent of age at onset of illness, illness duration, and neuroleptic dosage. Longitudinally, dysfunctions in the patients' secondary verbal memory fluctuated over time and with negative symptoms, and persisted in remitted patients at the same level as in their relatives. In conclusion, the secondary verbal memory met the criteria of relative stability and sensitivity in our sample of simplex-families. Thus, the secondary verbal memory seems to be a potential endophenotypic marker of schizophrenia, even for cases with a hypothetically lower genetic loading.

Neuropsychological functioning in first-break, never-medicated adolescents with psychosis

The purpose of the current study was to examine neuropsychological functioning in a group of never-medicated first-break adolescents with psychosis. It is the first report of cognition in a sample of adolescents with psychosis in which all patients were drug-naive. Twenty-nine adolescent patients (mean age = 16.07; SD = 2.00; 15 male and 14 female patients) experiencing their first psychotic episode and 17 age-matched and sex-matched normal volunteers (mean age = 16.88; SD = 2.39; 9 male and 8 female subjects) were recruited and assessed with a neuropsychological battery. Measures of attention, memory, language, executive functioning, perceptual motor processing, and motor speed were obtained. Psychiatric symptomatology, estimated verbal IQ, and parental socioeconomic status were also determined. Patients with psychosis were significantly more impaired than normal volunteers; effect sizes were greatest in the areas of executive functioning, attention, and memory, and significantly smaller in areas of language, perceptual motor processing, and motor speed. The pattern was not altered when differences in verbal IQ and parental socioeconomic status were controlled. Sex and age interactions indicated that younger male patients were particularly impaired. The findings demonstrate neuropsychological deficits in adolescents with psychosis and suggest that cognitive deficits are core symptoms in psychotic disorders.

Schizophrenia and the stroop effect

Conflict between irrelevant words and relevant colors in the Stroop task creates interference, long considered a measure of how well individuals focus attention. In the traditional card version of the Stroop task, schizophrenia patients exhibit increased interference, consistent with the distractibility they exhibit in everyday life. In contrast, on other versions of the Stroop task they show augmented facilitation (faster responding to congruent than to neutral trials). We suggest that schizophrenia patients possess adequate attentional resources to avoid interference when each letter string is presented individually but face difficulty when delays are imposed and multiple attentional demands appear. Although psychiatric symptomatology may contribute to different patterns of performance, there is no evidence that medication modulates this.

Cognitive functioning in young people with first episode psychosis: relationship to diagnosis and clinical characteristics

OBJECTIVE

To examine the extent and nature of neuropsychological deficits in adolescents and young people with first episode psychosis (FEP), and to determine whether the pattern and extent of neuropsychological deficits varied according to diagnosis.

METHOD

A total of 83 FEP subjects aged 13-25 years, and 31 healthy controls completed a comprehensive battery of neuropsychological tests, grouped into 10 cognitive domains. First episode psychosis subjects were stratified into three diagnostic groups (schizophrenia, affective disorders, substance-induced psychosis) and differences in cognitive profiles were examined. The contribution of demographic and clinical characteristics to cognitive performance was also explored.

RESULTS

The schizophrenia group demonstrated significantly worse performance on tasks of verbal learning and memory than the affective disorders group. Compared to healthy controls, the schizophrenia group also demonstrated global impairment across the majority of cognitive domains. The substance-induced group's performance lay between that of the schizophrenia and affective disorders groups. Analyses of differential deficits revealed that verbal learning, verbal memory and current intellectual functioning were selectively impaired in the schizophrenia group, whereas the affective disorders group demonstrated a selective deficit in speeded processing. Premorbid intellectual functioning, negative symptomatology and medication levels were the strongest predictors of cognitive performance in FEP subjects.

CONCLUSIONS

Verbal memory deficits differentiate individuals with schizophrenia from those with psychotic affective disorders. Although significant cognitive deficits are evident across all diagnostic FEP groups, individuals with schizophrenia appear to have more generalized impairment across a broad array of cognitive functions than other psychotic diagnoses. Lower premorbid intellectual functioning does not appear to contribute to greater cognitive deterioration following onset of psychosis, but severity of illness may be a more important factor than levels of mood disturbance.

Review of cognition and brain structure in schizophrenia: profiles, longitudinal course, and effects of treatment

Research on the cognitive and brain structural correlates of schizophrenia has seen tremendous progress over the past decade. It has become increasingly clear that there is no pathognomic neuropsychological or structural neuroanatomic profile in schizophrenia, likely due in part to etiological heterogeneity within the disorder. Nonetheless, several studies have indicated that verbal episodic memory and vigilance deficits are particularly prominent, and are observed even in untreated patients in their first episode of the disorder. The course of schizophrenia appears to be somewhat variable, and factors that contribute to the development of the illness, and in some patients, deterioration of cognitive functioning, have not been elucidated clearly. Neurodevelopmental factors, however, likely play an important role in the diathesis of the disorder, while neuropathological processes contribute to deterioration and progression. At this time, there are relatively few controlled comparisons of the cognitive effects of atypical and conventional antipsychotic medications. Additional studies of the potential effects of antipsychotic medications on structural brain abnormalities are warranted. It is hoped that newer innovative psychopharmacological approaches and neuropsychological remediation programs will, in the not-too-distant future, provide clinicians with a variety of means to improve the cognitive and social functioning of their patients.

Neuropsychological Deficits and Concomitant Clinical Symptoms in Schizophrenia

The most frequently reported neuropsychological deficits in schizophrenia are those of attention, executive function, and verbal memory. Whereas the former appear to be related to negative symptoms of schizophrenia, there is little agreement about which clinical symptoms are related to the verbal memory deficit. The aim of the present study was to delineate further the pattern of neuropsychological deficits in schizophrenia—especially those of verbal memory—and their relationship to clinical symptoms. One hundred patients with chronic schizophrenia and 62 healthy control subjects took part in the study. Assessments of patients took place within the first 3 weeks after admission to hospital. Nine neuropsychological tests, mainly measuring executive and memory function and attention, were administered to all subjects, and clinical symptoms, such as psychotic and negative symptoms and conceptual disorganization, were assessed in patients by means of the Positive and Negative Syndrome Scale (PANSS). Patients showed widespread cognitive deficits with verbal memory impairment best discriminating patients and controls. Conceptual disorganization was partly accounted for by poor verbal memory and a low IQ estimate, and negative symptoms by deficient word fluency; positive symptoms were not significantly related to cognitive deficits. The results indicate that there is a specific relationship between neuropsychological deficits and the more chronic of the clinical symptoms.

Episodic memory in schizophrenic patients and their relatives

BACKGROUND

Memory dysfunction among healthy relatives of patients with schizophrenia suggests that genetic liability to the disorder can also be manifested as cognitive impairment. This study was designed to further elucidate the nature of the memory dysfunction being transmitted.

METHOD

Memory function was assessed in 62 schizophrenic patients, 98 of their healthy relatives and 66 controls. Material-specific immediate/delayed recall and percentage retention were investigated using the Logical Memory and Visual Reproduction tests of the Wechsler Memory Scale (WMS). A third subtest of the WMS, the Associate Learning and a visual analogue of it, the Abstract Paired Associates, were used to measure verbal and visual learning. Current general intellectual function was assessed using a five-subtest short-form of the Wechsler Adult Intelligence scale-Revised (WAIS-R).

RESULTS

Schizophrenic patients performed significantly worse than controls on nearly all measures. Their relatives also showed significant deficit on the immediate and delayed recall of the Logical Memory, immediate recall of the Visual Reproduction, and the Abstract Paired Associates tests. Logical memory was substantially more impaired than the other measures for both patients and relatives. The deficit in immediate recall of the Logical Memory remained significant even after excluding those relatives with an Axis I diagnosis and schizotypal personality disorder. These findings were despite the relatives having an equivalent level of general intellectual function to that of controls.

CONCLUSION

Familial, presumed genetic, liability to schizophrenia may be expressed as dysfunction in verbal memory.

Verbal declarative memory dysfunction in schizophrenia: from clinical assessment to genetics and brain mechanisms

The recent literature on the neuropsychology of schizophrenia has emphasized memory deficits as a key area of impairment. Abnormalities in the medial temporal lobe, a brain region crucial for long-term memory formation, have also consistently been reported. We conducted a comprehensive review of verbal declarative memory (VDM) in schizophrenia with the aim of systematically addressing the nature of this impairment. We conclude that verbal declarative memory is significantly impaired in schizophrenia and is largely accounted for by deficits in the encoding stage. Subtle impairments in increased rates of forgetting are present, but are mild compared with those in amnestic disorders. Impairment in other cognitive domains studied thus far (e.g., attention), medication effects, or fluctuations in symptoms do not completely account for the deficit. VDM is among the most impaired neurocognitive domains in schizophrenia (along with attention and executive functions). Milder encoding deficits are present in high-risk subjects and non-psychotic relatives of individuals with schizophrenia suggesting that components of the deficit are associated with a genetic vulnerability to the illness, and are independent of the frank psychotic illness. Furthermore, VDM is observed in individuals experiencing their first-psychotic episode and it remains fairly consistent over time. Preliminary imaging studies and other work suggest abnormalities in prefrontal-hippocampal processing networks. Future work should emphasize delineating specific information processing components contributing to the deficit. This would allow imaging studies to determine which brain regions contribute to specific information processing deficits in schizophrenia.