Remote Ecological Momentary Testing of Learning and Memory in Adults With Serious Mental Illness

Smartphone-based ecological mobile cognitive tests (EMCTs) can measure cognitive abilities in the real world, complementing traditional neuropsychological assessments. We evaluated the validity of an EMCT of recognition memory designed for use with people with serious mental illness, as well as relevant contextual influences on performance. Participants with schizophrenia (SZ), schizoaffective disorder, and bipolar disorder (BD) completed in-lab assessments of memory (Hopkins Verbal Learning Test, HVLT), other cognitive abilities, functional capacity, and symptoms, followed by 30 days of EMCTs during which they completed our Mobile Variable Difficulty List Memory Test (VLMT) once every other day (3 trials per session). List length on the VLMT altered between 6, 12, and 18 items. On average, participants completed 75.3% of EMCTs. Overall performance on VLMT 12 and 18 items was positively correlated with HVLT (ρ = 0.52, P < .001). People with BD performed better on the VLMT than people with SZ. Intraindividual variability on the VLMT was more specifically associated with HVLT than nonmemory tests and not associated with symptoms. Performance during experienced distraction, low effort, and out of the home location was reduced yet still correlated with the in-lab HVLT. The VLMT converged with in-lab memory assessment, demonstrating variability within person and by different contexts. Ambulatory cognitive testing on participants’ personal mobile devices offers more a cost-effective and “ecologically valid” measurement of real-world cognitive performance.     

Computer-assisted cognitive rehabilitation reduces negative symptoms in the severely mentally ill

Thirty-four-day treatment program clients diagnosed with schizophrenia or schizoaffective disorder were randomly assigned to a computer-assisted cognitive rehabilitation (CACR) group or a wait-list Control group. CACR clients received 16 CACR sessions over an 8-week period. Measures of cognitive functioning, negative symptoms and self-esteem were administered at the beginning and end of this period. CACR clients showed greater improvement in cognitive functioning (verbal memory and attention) and negative symptoms. Symptom reduction was not mediated by raised self-esteem. CACR's effects may go beyond cognitive remediation to include some of the most disabling and refractory clinical features of schizophrenia.     

Cognitive remediation therapy (CRT) for young early onset patients with schizophrenia: an exploratory randomized controlled trial

BACKGROUND: Schizophrenia with an onset in adolescence is known to be associated with a poorer outcome and cognitive difficulties. These impairments have an impact on quality of life and represent treatment targets. Cognitive remediation therapy (CRT) attempts to improve cognitive deficits by teaching information processing strategies through guided mental exercises. The objective of this study is to evaluate the efficacy of CRT in alleviating cognitive deficits compared to treatment as usual and explore the mediating and moderating effects of cognitive improvement. METHOD: Single-blind randomized controlled trial with two groups, one receiving CRT (N21) and the other standard care (N19) assessed at baseline, 3 months (post therapy) and follow-up (3 months post therapy). Participants were recruited from specialist inpatient and community mental health services and were young patients with recent onset schizophrenia (average age of 18) and evidence of cognitive and social behavioural difficulties. The intervention was individual cognitive remediation therapy delivered over a period of 3 months with at least three sessions per week. The main outcome measures were cognition (memory, cognitive flexibility and planning) and secondary outcomes (symptoms, social contacts and self-esteem). RESULTS: Compared to standard care, CRT produced significant additional improvements in cognitive flexibility as measured by the Wisconsin Card Sort Test (WCST). Therapy moderated the effects of improved planning ability on symptoms such that improvements only had a beneficial effect when they were achieved in the context of CRT. Improvements in cognition in all domains had a direct effect on social functioning and improvements in WCST had a direct effect on overall symptom improvement. CONCLUSIONS: Cognitive remediation therapy can contribute to the improvement in WCST even in adolescents. The changes in cognitive outcomes also contributed to improvements in functioning either directly or solely in the context of CRT. Evidence of the mediator and moderator effects of cognitive changes should lead to more effective therapy development.     

首发精神分裂症的认知功能与阴,阳性症状和抗精神病药物效应的关系

目的 探讨首发精神分裂症认知功能与阴、阳性症状和抗精神病药物效应的关系。方法 对７８例精神分裂症患者给予氯丙嗪或氯氮平治疗,于治疗前及治疗１２周末各作一次Ｗｉｓｃｏｎｓｉｎ卡片分类测验（ＷＣＳＴ）、韦氏成人智力量表（ＷＡＩＳＲ）、韦氏记忆量表（ＷＭＳ）、语言流利性测验等。另外,４５例正常人也做了上述测验。结果 首发精神分裂症患者存在广泛的认知功能障碍,上述则查结果均较正常对照组差,尤以ＷＣＳＴ明显     

The effect of treatment with risperidone,olanzapine or phenothiazines on cognitive functions in patients with schizophrenia

INTRODUCTION: Theaimofthestudywastocomparetheeffectsofrisperidone, olanzapine and phenothiazines on cognitive functions in schizophrenia during short-term (4 &#45 6 weeks) and long-term (3 &#45 4 months) treatment. METHOD: Seventy patients with schizophrenia were investigated: 30 treated with risperidone, 20 with olanzapine and 20 with phenothiazines, in standard doses. Psychometric measurements were made with the Positive and Negative Syndrome Scale (PANSS), and neuropsychological tests included the Trail Making Test (TMT), the Stroop Test and the Wisconsin Card Sorting Test (WCST). RESULTS: PANSS negative symptoms decreased significantly after risperidone and olanzapine, did not change after short-term, and improved marginally after long-term, phenothiazine treatment. Risperidone treatment resulted in significant amelioration of performance on all neuropsychological tests after both short- and long-term treatment. Olanzapine gave benefit on five out of seven subtests, although in most instances this effect was noted only after long-term treatment. Olanzapine was inferior to risperidone in improving WCST performance. Treatment with phenothiazines brought about improvement on two subtests while the results on three showed significant deterioration. CONCLUSION: The results obtained suggest that novel antipsychotics show differential effect on cognition, with risperidone especially improving working memory; however, their effect on negative symptoms and cognitive functions is better than that of typical neuroleptics.     

Risperidone,negative symptoms and cognitive deficit in schizophrenia: an open study

The aim of this study was to evaluate the effects of a new antipsychotic compound on negative symptoms and cognitive deficit in schizophrenia. Psychiatric symptoms and cognition were assessed in 25 patients with schizophrenia, at baseline and after they had taken risperidone for 4 weeks. The Positive and Negative Symptoms Scale (PANSS), the Wisconsin Card Sorting Test (WCST) and two WAIS sub-tests were used to assess the patients. After the study period, both negative and positive symptoms and also measures of cognitive performance improved significantly. The WCST results correlated with negative symptom scores before and after treatment. This suggests that negative symptoms and cognitive deficit have a common underlying substrate which is the target of the risperidone treatment. Our data show that risperidone may have a substantial effect on complex cognitive functions in schizophrenia, and they suggest that certain cognitive deficits are relatively dependent on the negative symptoms of this disorder.     

A comparison of remediation techniques on the Wisconsin Card Sorting Test in schizophrenia

A wealth of evidence has revealed that deficits on a commonly used measure of executive-function, the Wisconsin Card Sorting Test (WCST), can be improved through a variety of methods of instruction in patients with schizophrenia. Relatively little is known however, which of these remediation methods produce strongest and most durable effects and whether these effects generalize to other, untrained executive-function measures. Two of the most commonly studied methods for remediation on the WCST, step-by-step didactic instruction on the task and utilization of self-monitoring strategies, have both been shown to improve WCST performance, yet have never been directly compared. Thirty-four participants with schizophrenia were randomly assigned to one of three experimental conditions: Condition A consisted of didactic training which incorporated a detailed account of changing sorting principles throughout the test; Condition B consisted of a self-monitoring strategy that required that participants verbalize their strategies out loud after each card sort; Condition C was a non-trained control group that received the same outcome assessments as the two training groups at identical time intervals without intervening training. Patients were assessed with the WCST and two other executive-function tests immediately prior to training, immediately after training and at a 1-month follow-up. Results revealed: (1) participants assigned to the didactic and self-monitoring conditions made significant gains on the WCST relative to a no-intervention control condition; (2) the effects of self-monitoring, but not didactic training, were evident at a one-month follow-up; and (3) only participants assigned to the self-monitoring condition showed generalization to a second, non-trained measure of executive-function. The significance of these results for implementation of strategies for comprehensive and sustained programs of remediation are discussed.     

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.     

Relationship of psychopathological symptoms and cognitive function to subjective quality of life in patients with chronic schizophrenia

Aims:  The purpose of the present study was to examine the extent of the effects of psychopathological symptoms and cognitive function on quality of life (QOL) in patients with chronic schizophrenia.
Methods:  Data were obtained using the Japanese Schizophrenia Quality of Life Scale (JSQLS), Positive and Negative Syndrome Scale (PANSS), Wisconsin Card-Sorting Test (WCST) Keio version, and Continuous Performance Test (CPT) for 52 schizophrenia patients.
Results:  Stepwise regression analysis showed that PANSS depression/anxiety factors predicted JSQLS psychosocial conditions and motivation/energy, and that WCST Categories Achieved predicted JSQLS symptoms/side-effects.
Conclusions:  Psychopathological symptoms and cognitive function affect subjective QOL in patients with schizophrenia. If the final goal is treatment that improves QOL in a manner that patients themselves are aware of, clinicians probably need to consider a treatment strategy that improves depression/anxiety symptom.     

Effects of Attention Process Training on cognitive functioning of schizophrenic patients

The goal of this study was to investigate the impact of Attention Process Training (APT) on cognitive functioning in schizophrenia. Twenty-four patients with schizophrenia were randomly assigned to one of the two following conditions: training by means of APT or no training. The dependent variables included measures of attention, memory and executive functions derived from a cancellation task, dichotic listening, dual task, Trail Making Test, Paced Auditory Serial Addition Task, Everyday Attention Questionnaire, Spain-Complutense Verbal Learning Test and Wisconsin Card Sorting Test (WCST). All participants were also rated on measures of positive and negative symptoms. The tasks were administrated to all participants at baseline. Participants in the training group received individual intensive APT twice a week, whereas the control group did not receive training. All participants were subsequently retested on the same tests. Although, contrary to expectations, neither group improved on clinical and information-processing measures of attention and memory, patients in the trained group had a significantly higher performance on executive function (as measured by the WCST) than did the control group. We conclude that it is feasible to use practice in attention to remediate executive function deficits in schizophrenia.     

A Meta-analysis of Cognitive Remediation for Schizophrenia: Efficacy and the Role of Participant and Treatment Factors

The number of randomized, controlled studies of cognitive remediation (CR) for schizophrenia, a therapeutic approach designed to improve cognitive skills and function, has grown substantially over the past 20 years. Active elements of CR treatment, however, remain unknown. The current meta-analysis investigated treatment, study, and participant factors in the size of observed treatment effects. Electronic databases were searched up to May 2020 using variants of the key words “cognitive remediation,” “clinical trials,” and “schizophrenia.” This search produced 73 unique, randomized, controlled trials. Data were independently extracted by 3 reviewers with excellent reliability. Random-effects models were used to assess primary cognitive and secondary symptom and functional outcomes. Moderator analyses investigated the role of a variety of treatment, study, and participant factors. The meta-analysis (4594 participants) revealed that CR produced significant small-to-moderate size improvements in all domains of cognition studied (Hedge’s gs = .19–.33). and a significant small improvement in function (Hedge’s g = .21). CR programs that included a discussion (“bridging”) group to help apply acquired cognitive skills to everyday life produced larger effects on global cognition and verbal memory. CR programs with strategy-coaching produced larger effects on episodic memory. Sample age, gender, positive, negative, and overall symptoms, and medication dose did not serve as barriers to treatment gains. CR produces small-to-moderate improvements in cognition and function in schizophrenia. Programs of CR that utilize bridging groups and strategy-coaching are more cognitively potent. Future research should focus on ways to modify CR to bolster generalization of cognitive improvements to function.     

Study of positive and negative feedback sensitivity in psychosis using the Wisconsin Card Sorting Test

BackgroundSchizophrenia involves marked motivational and learning deficits that may reflect abnormalities in reward processing. The purpose of this study was to examine positive and negative feedback sensitivity in schizophrenia using computational modeling derived from the Wisconsin Card Sorting Test (WCST). We also aimed to explore feedback sensitivity in a sample with bipolar disorder.MethodsEighty-three individuals with schizophrenia and 27 with bipolar disorder were included. Demographic, clinical and cognitive outcomes, together with the WCST, were considered in both samples. Computational modeling was performed using the R syntax to calculate 3 parameters based on trial-by-trial execution on the WCST: reward sensitivity (R), punishment sensitivity (P), and choice consistency (D). The associations between outcome variables and the parameters were investigated.ResultsPositive and negative sensitivity showed deficits, but P parameter was clearly diminished in schizophrenia. Cognitive variables, age, and symptoms were associated with R, P, and D parameters in schizophrenia. The sample with bipolar disorder would show cognitive deficits and feedback abnormalities to a lesser extent than individuals with schizophrenia.ConclusionNegative feedback sensitivity demonstrated greater deficit in both samples. Idiosyncratic cognitive requirements in the WCST might introduce confusion when supposing model-free reinforcement learning. Negative symptoms of schizophrenia were related to lower feedback sensitivity and less goal-directed patterns of choice.     

Effects of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism on executive function in schizophrenia

BACKGROUND: The methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism has been associated with both overall schizophrenia risk and severity of negative symptoms. This study examined whether schizophrenia patients homozygous for the risk allele (T/T) exhibit greater impairment in executive function, and determined the extent to which MTHFR's effects on negative symptoms underlie this relationship. METHODS: 200 outpatients with chronic schizophrenia were evaluated with the Verbal Fluency Test (VFT), Wisconsin Card Sort Test (WCST), and California Verbal Learning Test (CVLT). Performance was stratified by MTHFR C667T genotype. Path analysis determined the extent to which MTHFR effects on negative symptoms mediated the relationship between genotype and cognitive measures. RESULTS: T/T subjects exhibited significantly greater deficits on the VFT and had more difficulty achieving the first category on the WCST. Genotype groups did not differ in CVLT performance. C677T effects on negative symptoms contributed to, but did not fully account for, genotype effects on VFT. Negative symptoms did not mediate WCST performance. CONCLUSIONS: MTHFR C677T genotype contributes to certain executive function deficits in schizophrenia. These deficits remained significant when taking into account mediating effects of negative symptoms. Although the intermediate mechanisms for C677T effects remain uncertain, these results suggest that MTHFR-related cognitive impairment and negative symptoms reflect differing neural substrates.     

Identifying Cognitive Remediation Change Through Computational Modelling—Effects on Reinforcement Learning in Schizophrenia

Objective: Converging research suggests that individuals with schizophrenia show a marked impairment in reinforcement learning, particularly in tasks requiring flexibility and adaptation. The problem has been associated with dopamine reward systems. This study explores, for the first time, the characteristics of this impairment and how it is affected by a behavioral intervention—cognitive remediation. Method: Using computational modelling, 3 reinforcement learning parameters based on the Wisconsin Card Sorting Test (WCST) trial-by-trial performance were estimated: R (reward sensitivity), P (punishment sensitivity), and D (choice consistency). In Study 1 the parameters were compared between a group of individuals with schizophrenia (n = 100) and a healthy control group (n = 50). In Study 2 the effect of cognitive remediation therapy (CRT) on these parameters was assessed in 2 groups of individuals with schizophrenia, one receiving CRT (n = 37) and the other receiving treatment as usual (TAU, n = 34). Results: In Study 1 individuals with schizophrenia showed impairment in the R and P parameters compared with healthy controls. Study 2 demonstrated that sensitivity to negative feedback (P) and reward (R) improved in the CRT group after therapy compared with the TAU group. R and P parameter change correlated with WCST outputs. Improvements in R and P after CRT were associated with working memory gains and reduction of negative symptoms, respectively. Conclusion: Schizophrenia reinforcement learning difficulties negatively influence performance in shift learning tasks. CRT can improve sensitivity to reward and punishment. Identifying parameters that show change may be useful in experimental medicine studies to identify cognitive domains susceptible to improvement.Key words: reward systems, cognitive remediation, therapy, sensitivity, Wisconsin Card Sorting test, reward sensitivity, dopamine     

Cognitive predictors of skill acquisition on social problem solving in patients with schizophrenia

The aim of the study was to evaluate the relationship between social problem solving ability, clinical features and cognitive functions, and determine the predictors of benefit from social problem solving training in 63 patients with schizophrenia. We administered Brief Psychiatric Rating Scale (BPRS), Wisconsin Card Sorting Test (WCST), Digit Span Test, Continuous Performance Test (CPT) and the Assessment of Interpersonal Problem Solving Skills (AIPSS). Only BPRS-positive symptoms subscale was negatively related to AIPSS on linear regression analysis. After the completion of the pretest, the patients were randomized to either problem solving training (n = 32) or control groups (n = 31). Patients in training group received 6 weeks problem solving training in-group modality, and those in control group were treated as usual. We readministered AIPSS at the end of 6 weeks. There were significant changes from pretest to posttest on AIPSS-total, AIPSS-receiving skills, and AIPSS-processing skills score in training group but not in control group. The number of correct answers in WCST and CPT hit rate were the predictors of post-training AIPSS scores in training group. Our findings suggest that skill acquisition on social problem solving is related with cognitive flexibility and sustained attention.     

Report From the Working Group Conference on Multisite Trial Design for Cognitive Remediation in Schizophrenia

The National Institute of Mental Health (NIMH)-Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Project and related efforts have stimulated the initiation of several studies of pharmacologic treatments for cognitive impairment in schizophrenia. Cognitive remediation may provide an excellent platform for the provision of new learning opportunities and the acquisition of new skills for patients who are engaged in pharmacologic trials to improve cognition. However, it is not clear how a cognitive remediation intervention would be employed in multisite clinical trials. A meeting of experts on cognitive remediation and related methodological topics was convened to address the feasibility and study design issues for the development of a multisite trial of cognitive remediation in schizophrenia called the Cognitive Remediation in the Schizophrenia Trials Network study. This report details the findings from this meeting, which included the following 4 conclusions. (1) A multisite trial of a cognitive remediation intervention using a network of diverse research sites would be of great scientific value. (2) Various interventions could be employed for this multisite trial. (3) Programs that do not address key motivational and interpersonal aspects of cognitive remediation may benefit from supplementation with “bridging groups” that allows patients to meet with others and to apply their newly acquired cognitive skills to everyday life. (4) Before a multisite efficacy trial is initiated, a pilot study could demonstrate the feasibility of conducting a trial using a cognitive remediation intervention.     

精神分裂症认知障碍及其与阴性阳性症状的关系

目的 探索精神分裂症认知障碍特点及其与阴性阳性症状之间的关系。方法 比较32例从未用过抗精神病药或停药2周以上的精神分裂症患者以及15例健康受试者的事件相关电位(ERPs)和威斯康星卡片分类测验成绩(WCST),并进行相关分析。结果 与正常受试者比较,多个位点N2和P3波潜伏期延长,P3波幅降低。WCST中分类完成数偏少,持续错误数和总错误数增加。N2潜伏期和波幅与PANSS阳性症状分呈负相关,而WCST总错误数与PANSS总分和阴性症状总分正相关。结论精神分裂症病人存在中枢信息处理障碍,认知障碍与阴性阳性症状之间具有一定的内在联系。     

Genetic and state variables of neurocognitive dysfunction in schizophrenia: a twin study

To characterize the familiality of cognitive dysfunction in schizophrenia, we studied performance on three tasks (visuospatial attention; visuolinguistic conflict, arrow-word; and Wisconsin Card Sorting Test [WCST]) by monozygotic (MZ) and dizygotic (DZ) twin pairs discordant for schizophrenia. The subject sample consisted of six MZ twin pairs, nine DZ twin pairs, and one MZ and one DZ nonschizophrenia cotwin of a patient with schizophrenia. There were two sources of cognitive dysfunction: a nonheritable, state component and a heritable, trait component. Deficits surfaced during the WCST in nonschizophrenia MZ cotwins; this impairment resolved following training in nonschizophrenia MZ cotwins, but not in the probands with schizophrenia, who performed abnormally in all tasks. The results suggest that nonheritable protective factors modulate the specific, plastic, and sometimes subtle neurocognitive deficits related to the schizophrenia genotype.     

When Top-Down Meets Bottom-Up: Auditory Training Enhances Verbal Memory in Schizophrenia

A critical research priority for our field is to develop treatments that enhance cognitive functioning in schizophrenia and thereby attenuate the functional losses associated with the illness. In this article, we describe such a treatment method that is grounded in emerging research on the widespread sensory processing impairments of schizophrenia, as described elsewhere in this special issue. We first present the rationale for this treatment approach, which consists of cognitive training exercises that make use of principles derived from the past 2 decades of basic science research in learning-induced neuroplasticity; these exercises explicitly target not only the higher order or “top-down” processes of cognition but also the content building blocks of accurate and efficient sensory representations to simultaneously achieve “bottom-up” remediation. We then summarize our experience to date and briefly review our behavioral and serum biomarker findings from a randomized controlled trial of this method in outpatients with long-term symptoms of schizophrenia. Finally, we present promising early psychophysiological evidence that supports the hypothesis that this cognitive training method induces changes in aspects of impaired bottom-up sensory processing in schizophrenia. We conclude with the observation that neuroplasticity-based cognitive training brings patients closer to physiological patterns seen in healthy participants, suggesting that it changes the brain in an adaptive manner in schizophrenia.     

Comorbid substance abuse and neurocognitive function in recent-onset schizophrenia

Despite the high prevalence of comorbid substance use disorder (SUD) up to 65% in schizophrenia there is still few knowledge about the influence of substance abuse on neurocognitive function. In a prospective design we recruited 68 patients (aged 18–40 years) diagnosed as recent-onset schizophrenia or schizoaffective disorder consecutively admitted to hospital. The patients received standardized psychopathological evaluation of schizophrenic symptoms [Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Negative Symptoms (SANS)], depressive symptoms [Montgomery Asberg Depression Rating Scale, (MADRS)] and global ratings [Clinical Global Impressions Scale (CGI), Global Assessment of Functioning Scale (GAF)]. Out of this sample 44 subjects underwent after stabilization (4–6 weeks after admission) neuropsychological investigation focusing on early information processing (Trail-Making-Test A, Digit Span), visuo-spatial ability (Corsi Block Tapping), verbal fluency (Verbal Fluency Test, semantic and letter category), and executive functioning and cognitive flexibility [Trail-Making-Test B, Wisconsin Card Sorting Test (WCST)]. About 36% of patients reported drug abuse [European Addiction Severity Index (EuropASI)] with a high prevalence for cannabis. Compared with nonabusers the sample of substance abusers was younger, predominantly male and had lower socioeconomic status. Attentional impairment according to the SANS subscale was less in abusers than in nonabusers on admission, no other psychopathological differences could be detected. Schizophrenic patients without substance abuse demonstrated significantly better performance only in a few neurocognitive tasks (Verbal Fluency, letter category and at trend level Digit Span, backwards), while there tended to be an advantage for substance abusers in executive functioning (WCST, not significant). These results are consistent with other studies of first-episode patients. The lack of higher cognitive disturbance in young schizophrenic patients with comorbid substance abuse may encourage clinicians to develop integrated treatment programmes using cognitive strategies of drug therapy.