ERP study of pre-attentive auditory processing in treatment-refractory schizophrenia

Event-related potential (ERP) studies have demonstrated impaired auditory sensory processing in patients with schizophrenia, as reflected in abnormal mismatch negativity (MMN). We sought to extend this finding by evaluating MMN in 13 treatment-refractory patients with schizophrenia, and 14 age- and gender-matched healthy controls. Subjects responded to infrequent visual stimulation while ignoring binaurally presented auditory tones. The amplitude and topographical pattern of the MMN were analyzed. The control group presented the expected reduction in the amplitude of the MMN from frontal to central and parietal locations. In comparison, the MMN amplitude was not reduced in the treatment-refractory patients, and was largest at the central-posterior electrode location. In addition, patients displayed larger negativities at left frontal, and left- and right-temporal electrode locations than the control subjects. These findings are consistent with pre-attentive abnormalities in treatment-refractory patients with schizophrenia.

Cognitive function and depression in symptom resolution in schizophrenia patients treated with an atypical antipsychotic

OBJECTIVE

To investigate which cognitive and affective features contribute most to responder/non-responder group separation during a switching trial with atypical antipsychotic.

DESIGN

A prospective open trial with an atypical antipsychotic (olanzapine).

PATIENTS

One hundred and thirty-four patients meeting diagnostic criteria for schizophrenia, schizophreniform or schizoaffective disorder began an 8-week open-label olanzapine treatment at a dose of 5 mg/day which was increased to 10 mg/day after one week.

INTERVENTIONS

Olanzapine during 8 weeks. Patients were considered as responders if their BPRS score decreased of at least 20% (n = 96) and non-responders if it did not (n = 38). Neuropsychological assessments were carried out at baseline, at four and at eight weeks.

RESULTS

Neurocognitive measures were analyzed for discriminate factors between responder and non-responder groups. A regression analysis was applied to explain the effects of depression on each cognitive variable. Depression was found to be a weak discriminant factor, however this finding could not firmly establish that depression is a potential factor in explaining deficits and improvements in cognition.

Assessment of executive dysfunction during activities of daily living in schizophrenia

Many neuropsychological studies have described deficits of memory and executive functions in patients with schizophrenia, and the severity of these deficits seems to be determinant in predicting the community outcome of these patients [Schizophr. Bull. 26 (2000) 119]. However, neuropsychological evaluation does not provide valuable information about how the cognitive deficits directly affect daily living, that is, which cognitive deficit affects which behavior. The present study aimed at determining whether executive dysfunction in schizophrenia could be directly measured by analyzing three activities of daily living (ADL), in addition to assessing the ecological validity of commonly used neuropsychological tests. Within specific ADL (choosing a menu, shopping the ingredients, cooking a meal), the sequences of behaviors that have been performed by 27 control subjects and 27 patients with schizophrenia were both analyzed by using a preset optimal sequence of behavior. When compared with control subjects, patients with schizophrenia showed more omissions when choosing the menu, more sequencing and repetitions errors during the shopping task, and more planning, sequencing, repetition and omission errors during the cooking task. These behavioral errors correlated significantly with negative, but not with positive symptoms of the patients. Furthermore, they also correlated with the poor performances on executive neuropsychological tests, especially those sensitive to shifting and sequencing abilities, but not with memory tests. These results suggest that executive deficits in schizophrenia may specifically affect ADL and that such deficits can be quantitatively assessed with a behavioral scale of action sequences.

Procedural learning in schizophrenia can reflect the pharmacologic properties of the antipsychotic treatments

BACKGROUND

Conventional and atypical antipsychotics have different affinities for D2 receptors, and these receptors are principally located in the striatum. Given that this cerebral structure was previously found to play a major role in procedural learning, the antipsychotic treatment in schizophrenia may be determinant for the procedural learning profile of these patients.

OBJECTIVE

The current study was aimed at verifying whether procedural learning differs in patients with schizophrenia treated with conventional antipsychotics and patients treated with atypical antipsychotics.

METHOD

Forty-five patients with schizophrenia were divided into 3 different groups according to their pharmacologic treatment: (1) haloperidol, a classical neuroleptic with high D2 receptor affinity; (2) clozapine, an atypical neuroleptic with practically no D2 receptor affinity; and (3) risperidone, an atypical neuroleptic that nevertheless shows high D2 receptor affinity. Patients were compared to 35 control subjects on a visuomotor procedural learning task (mirror drawing).

RESULTS

All patients were able to learn the task. However, those treated with haloperidol showed some degree of learning impairment, while those treated with clozapine or risperidone did not show this impairment. In addition, performance per se, regardless of the learning, was found to be affected in the haloperidol and risperidone, but not in the clozapine groups.

CONCLUSION

Procedural learning in schizophrenia may be differentially affected, depending on the pharmacologic profiles of the antipsychotics used for the treatment of this illness.

Self-assessed cognitive dysfunction and objective performance in outpatients with schizophrenia participating in a rehabilitation program

OBJECTIVE

To explore the pattern of associations between self-assessed and objective neuropsychological performance in a sample of outpatients with schizophrenia participating in a rehabilitation program.

METHOD

The Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS) [Compr. Psychiatry 44 (2003) 331] was used to assess cognitive complaints in 73 subjects with schizophrenia. Visuo-spatial tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) [Cogn. Neuropsychiatry 3 (1998) 45] were administered as objective measures.

RESULTS

Cognitive complaints in several cognitive domains were mainly correlated with a true difficulty in memory. Higher SSTICS attention scores, i.e. increased complaints, were associated with poorer CANTAB explicit visual memory and planning performances. Higher SSTICS executive functioning scores were associated with poorer CANTAB explicit visual memory scores.

CONCLUSION

These findings suggest that outpatients with schizophrenia express some cognitive difficulties. However, the cognitive nature of these subjective complaints does not strictly correspond with objective performances. These results also suggest that theoretical constructs of cognitive functions do not always have ecological validity. Thus, subjective cognitive complaints should be taken into account in assessment of patient well-being, but cannot be used as a substitute to objective cognitive measures. The simultaneous use of subjective and objective measures of cognitive dysfunction may provide a more complete picture of individual rehabilitation targets in patients with schizophrenia.

Long-term effect of prefrontal lobotomy on verbal fluency in patients with schizophrenia

OBJECTIVE

This study investigated the long-term effects of bilateral prefrontal leukotomy on lexical abilities in schizophrenia subjects.

METHOD

we compared performances of leukotomized (LSP), non-leukotomized schizophrenia patients (NLSP) and normal controls, using a test of verbal fluency. Multiple case and triple comparison design were implemented. i.e., the performance of each LSP was compared to that of NLSP and that of a normal control. The sample consisted of four LSP, four NLSP, and four normal subjects. Subjects were matched in sex, age, handedness, and schooling. In Addition, schizophrenia groups were matched in diagnosis and years of hospitalization. Quantitative and qualitative analyses of generated words and errors produced by subjects were carried out.

RESULTS

A deficiency in both groups of schizophrenia was observed, although a better performance in LSP patients was detected.

CONCLUSION

Intact Lexical ability in LSP indicates its poor relation to the frontal lobe.

Comparison between olanzapine and haloperidol on procedural learning and the relationship with striatal D2 receptor occupancy in schizophrenia

The striatum is known to play a primary role in procedural learning. In this study, the authors simultaneously assessed the effects of two antipsychotic drugs on procedural learning and on striatal dopamine (D2) receptor occupancy. Twenty-seven patients receiving either olanzapine or haloperidol as antipsychotic medication were assessed with the Computed Visual Tracking Task (CVTT) and Single Photon Emission Computed Tomography (SPECT) following the administration of Iodine 123-IBZM (123I-IBZM), a radioligand with a high affinity and specificity for the D2 receptors. The results showed poorer procedural learning in the haloperidol-treated patients than in normal control subjects, while no difference could be found between olanzapine-treated patients and normal control subjects. In the haloperidol but not the olanzapine group, significant correlations were found between procedural learning deficits and striatal D2 receptor occupancy. However, there was no significant difference in D2 receptor occupancy between olanzapine- and haloperidol-treated patients, and this may be related to the high doses of olanzapine and low doses of haloperidol administered. The authors concluded that: 1) striatal D2 receptor blockade may alter procedural learning in humans; and 2) olanzapine may have a protective effect on procedural learning, even at doses that produce striatal D2 receptor occupancy as high as that found with haloperidol. This protective effect of olanzapine may be related to its atypical pharmacological properties.

[Antipsychotic drugs. Risk factors for diabetes]

ANTIPSYCHOTICS AND DIABETES: After 50 years' use of antipsychotics, it is pertinent to draw-up a circumspect review of the side effects of these psychotropic agents. Moreover, few articles have attempted to elucidate the relationship between the monitoring of carbohydrate metabolism and the prescription of this type of medication. SEVERAL MECHANISMS AT THE ORIGIN OF AN IMBALANCE IN GLYCAEMIA: Antipsychotics, notably the atypical forms, represent an additional factor of risk for developing diabetes. The weight gain secondary to this treatment plays an important part in this imbalance, but other mechanisms may also contribute. DEPENDING ON THE TYPE OF ANTIPSYCHOTIC: Our present knowledge is insufficient to be able to quantify the effect of each atypical antipsychotic on diabetes. The only tendency that has been reproduced in several studies concerns the increased risk associated with dibenzodiazepine antipsychotics (clozapine and olanzapine), compared with the other antipsychotics.

[Diabetes and schizophrenia, which links?]

WHAT IS OBSERVED: Epidemiology and clinical practice show an increased prevalence of diabetes in schizophrenic patients, preceding even the use of antipsychotics. Several patho-physiological mechanisms have been proposed to explain the phenomenon, although none is completely satisfactory. SEVERE CONSEQUENCES: Diabetic schizophrenics exhibit a significantly greater number of other physical diseases than non-diabetic schizophrenic patients. These diseases are at the origin of early mortality and reduced quality of life. THE NEED FOR SCREENING: Schizophrenic patients should be included in the groups of those at risk for diabetes, together with patients treated with anti-psychotics. Diabetes is diagnosed if fasting blood sugar is>7.0 mmol/L and a glucose tolerance test>11,1 mmol/L.

IN PRACTICE

The epidemiology and extent of the impact on mortality and morbidity of the association between schizophrenia and diabetes mellitus requires particular attention of the practitioners and the screening for diabetes, its prevention and treatment must be conducted according to regularly updated guidelines.

Procedural learning in schizophrenia after 6 months of double-blind treatment with olanzapine, risperidone, and haloperidol

RATIONALE

First generation antipsychotics induce extrapyramidal motor symptoms (EPS), presumably through dopamine D(2) receptor blockade at the dorsal striatum. This may also produce impairment of cognitive processes, such as procedural learning, that are dependent on this region. Haloperidol and, to a lesser extent, risperidone, are active in the dorsal striatum and may induce EPS and impairment of procedural learning. In contrast, the prototypical second-generation antipsychotic, clozapine, is less active in the dorsal striatum and does not induce EPS or impair procedural learning. Olanzapine is pharmacologically similar to clozapine and has a low incidence of EPS induction.

OBJECTIVES

To assess the hypothesis that olanzapine would not have a deleterious effect on procedural learning.

METHODS

Thirty-nine subjects with early phase schizophrenia were randomly assigned to double blind treatment with haloperidol, risperidone, or olanzapine. They were administered the Tower of Toronto test at an unmedicated baseline and again following 6 weeks and 6 months of treatment.

RESULTS

Procedural learning, defined as the improvement observed between two blocks of five trials of the Tower of Toronto, was preserved after 6 weeks of all three treatments but showed a substantial decline after 6 months of treatment with haloperidol or risperidone.

CONCLUSIONS

These data are consistent with the differential activity of the three medications in dorsal striatum structures and suggest that the advantages of olanzapine over haloperidol and risperidone in relation to extrapyramidal syndromes may also generalize to procedural learning. The results also suggest that the procedural learning disadvantages of haloperidol and risperidone accrue slowly but are apparent after 6 months of treatment.

A Canadian multicenter trial assessing memory and executive functions in patients with schizophrenia spectrum disorders treated with olanzapine

Serial verbal learning task (explicit long-term memory) and verbal fluency (generation of a response) are tests that are usually severely impaired in schizophrenia. Despite the growing literature supporting the clinical efficacy of olanzapine, psychiatrists still question its cognitive consequences. This study assessed the efficacy of olanzapine on neurocognitive functioning. Patients (N = 134) meeting diagnostic criteria for schizophrenia, schizophreniform, or schizoaffective disorders began an 8-week, open-label olanzapine treatment at a dose of 5 mg/d, which was increased to 10 mg/d after 1 week. Daily dosage was subsequently adjusted between 5 and 20 mg/d based on individual clinical status. All previous antipsychotics were tapered and discontinued during the first 2 weeks of the study. Neuropsychologic assessments were carried out at baseline and at 4 and 8 weeks. Explicit long-term memory was assessed with the Rey Auditory-Verbal Learning Test: the average immediate recall score significantly improved (P < 0.001), as did the delayed recall score (P < 0.001). The average total score on category fluency improved from 34.6 words at baseline to 37.6 words at end point (P < 0.0001). Time on both Trail A and B making tasks significantly decreased (P < 0.0001). Lack of a control arm makes it impossible to exclude a practice effect as an explanation for the enhanced cognitive performance, although the Word List Recall test represents one of the better resources to avoid a practice effect. After switching to olanzapine, there was a statistically significant improvement of cognitive function in the 3 main domains tested and no significant worsening of any memory or executive function measure.

Sleep architecture and its clinical correlates in first episode and neuroleptic-naive patients with schizophrenia

The goal of the present study was to characterize sleep organization in first episode and neuroleptic-naive patients with schizophrenia and to evaluate relationships between those sleep parameters and clinical symptoms. Eleven patients with acute schizophrenia never treated with neuroleptics were compared to 11 healthy controls. Sleep stages and phasic events (sleep spindles and rapid-eye-movements during REM sleep (REMs) were visually identified. Clinical symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). Compared to controls, patients with schizophrenia had difficulty initiating sleep, decreased stage 4 duration, reduced rapid eye movement (REM) sleep latency, and normal sleep spindles and REMs densities. Positive symptoms correlated negatively with REM sleep latency. The BPRS total score correlated negatively with REM sleep duration and REMs density. The present results indicate that first episode and neuroleptic-naive patients with schizophrenia have difficulties initiating, but not maintaining, sleep. These results also confirm that the duration of stage 4 and REM sleep latency are reduced in first episode and neuroleptic-naive patients with schizophrenia. The fact that measures of REM sleep correlate with clinical scales of schizophrenia suggests that REM sleep physiology shares common substrates with symptoms of this disease.

Exploring cognitive complaints in schizophrenia: the subjective scale to investigate cognition in schizophrenia

While it has become commonplace to test the various components of memory in schizophrenia with paper-and-pencil or in-lab tasks, very little data exist on the subjective complaints of patients regarding their memory. Few instruments have been designed to collect systematically the complaints of patients with schizophrenia. We present a work in progress on the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS), a 21-item, Likert-type scale that is simple and easy to use. It allows a quantitative approach to the subjective and cognitive dimensions of schizophrenia. Stip constructed the scale based on a questionnaire covering several cognitive domains: memory (working memory, explicit long-term memory), attention (divided, distractibility, alertness, sustained), language, and praxia. We evaluated the psychometric properties of the SSTICS in a population of 114 French-speaking patients in Montreal. Patients were recruited in the community and assessed with the Structured Clinical Interview for DSM-III-R (SCID), the Positive and Negative Syndrome Scale (PANSS), and the Extrapyramidal Symptoms Rating Scale (ESRS). Cognition was measured using the Rey Auditory Verbal Learning Test (RAVLT) (long-term memory), Controlled Oral Word Association Test (verbal fluency), and Trails A and B. Preliminary analyses showed very good internal consistency for the global score (alpha=0.88), and alphas varying from 0.57 to 0.72 for the subscales. Stability over time was very good. The principal components analysis accounted for a multiple structure. Correlations between subjective scores and objective cognitive assessment were significant for several domains. Validation of the SSTICS needs to be completed through further exploration of the factorial structure and testing of the English version.

[Schizophrenia and addiction: An evaluation of the self-medication hypothesis]

Despite the fact that most researchers acknowledge the high prevalence of comorbid substance abuse among schizophrenic patients, there is no common agreement regarding the etiology of this serious public health problem. At the center of this debate though, Khantzian's self-medication hypothesis has captured most of the attention. In the present literature review, the authors evaluate this hypothesis in the light of our current knowledge. Formulated in a clinical context, in reaction to the psychoanalytic interpretation of addiction as a pleasure seeking pathology, Khantzian's hypothesis holds that schizophrenic patients use psychoactive substances to relieve their symptoms. Properly understood, this conjecture presupposes that, with the relief of certain target symptoms, substance use would no more be a necessity. But in reality, the use of psychoactive substances usually leads to a general deterioration of the patients' condition. Pharmacodependent schizophrenic patients relapse more often, they are more frequently hospitalized, they show more violent behaviors, and they are more frequently homeless. In particular, the positive symptoms of these patients are generally exacerbated by the psychoactive drugs--with the possible exception of opiates. This observation is in lign with the fact that psychostimulants (cocaine, amphetamines), anesthesic dissociatives (PCP, ketamine) as well as hallucinogens (cannabis, LSD) are all known to exert psychotomimetic effects. As for negative symptoms, the reality is more complex. Preliminary results certainly suggest that stimulants (minor or major) relieve these symptoms, but in the case of the other psychoactive substances, empirical evidence remains fragmentary. Still, the properties of psychoactive substances invite to pay close attention, among the negative symptoms, to the cognitive deficits, the social inaptitudes and the hedonic deficits of these patients. Unsatisfied with the self-medication hypothesis, an increasing number of researchers hypothesize that schizophrenic patients abuse drugs in hope to relieve the negative affects (stress, depression) that commonly accompany their symptomatology. Interestingly, increasing data link these negative manifestations and substance abuse among schizophrenic patients. But these same data do not elucidate whether these manifestations are primary or secondary to drug abuse. For the moment, these findings must be replicated. Furthermore, it remains to be clarified what negative affect is involved here. Is it stress, anxiety or, as commonly thought, depression? Other paths aim in the direction of personality traits and dissociation. The first path is suggested by recent studies demonstrating that pharmacodependent schizophrenic patients differ from non-abusing schizophrenics in that their personality is characterized by traits such as sensation seeking and impulsivity. As for the second path, it is suggested by a recurrent observation in addictive medicine practice, that is: alcohol, cannabis, ketamine, LSD, opiates, PCP, all these substances can induce dissociative states (depersonalization, derealization, etc.). Surprisingly, most of the hypotheses advanced so far have been formulated without reference to neuroscience. However, from a biological perspective, substance abuse among schizophrenic patients appears paradoxical: while the positive symptoms of schizophrenia might involve an hyperactivity of the reward system, the drugs of abuse all seem to increase dopamine release in that same system. That very paradox further casts some doubt on the self-medication hypothesis. And it opens an alternative: schizophrenic patients might be biologically vulnerable to the rewarding effects of drugs abuse. On the therapeutic level finally, the authors argue that polypharmacy medications such as clozapine and quetiapine, known to act on the reward system preferentially to the extrapyramidal system and known to dissociate fastly from the dopamine-D2 receptor, could simplify clinical intervention.

Clozapine, quetiapine and olanzapine among addicted schizophrenic patients: towards testable hypotheses

Although life prevalence of substance use disorders among patients with schizophrenia is close to 50%, few studies have been carried out to date to identify an integrated pharmacological treatment for this comorbidity. So far, the most promising results, that we report here, have been obtained with clozapine. To a lesser extent, quetiapine and olanzapine, both clozapine analogues, have also shown promising results. Further to these observations, the present paper critically reviews the advantages associated with clozapine, quetiapine and olanzapine, and their relevance to the treatment of addiction among schizophrenic patients. Six characteristics seem to distinguish clozapine, quetiapine and olanzapine from the first-generation antipsychotics: (1) acting preferentially on the reward system, these second-generation antipsychotics (mainly clozapine and quetiapine) induce almost no extrapyramidal symptoms; (2) quickly dissociating from D(2), theses drugs (mainly clozapine and quetiapine) seem not to induce dysphoria, unlike conventional antipsychotics like haloperidol;(3) these drugs (mainly clozapine) seem more effective in the treatment of negative symptoms than conventional antipsychotics; (4) because of a diversified activity on several serotoninergic and noradrenergic receptors, these drugs positively alter mood, which does not seem to be the case with conventional antipsychotics, except for flupenthixol; (5) these drugs have a positive impact on cognition, which is not the case with the first-generation antipsychotics; (6) unlike conventional antipsychotics, these drugs seem to have a moderate affinity for 5-HT(3), the receptor on which ondansetron, an anti-craving medication, acts.

Mild procedural learning disturbances in neuroleptic-naive patients with schizophrenia

This study investigated whether drug-naive patients with schizophrenia present procedural learning disturbances, given that this function is known to involve the striatum and that structural abnormalities of the striatum have been described in these patients. Eleven neuroleptic-free schizophrenic patients were compared with 11 healthy control subjects on a visuomotor procedural learning task (the Mirror Drawing Test). Average performance and learning rate did not differ between the two groups. However, schizophrenia patients were lower in learning smoothness (the consistency with which performance improves from trial to trial), which would indicate difficulty in benefiting from past experience to perform better on a current task. Because low smoothness has recently been found to be associated with striatal dysfunction, these results might indicate a premature dysfunction of the striatum in young drug-naive patients with schizophrenia. However, this dysfunction is not severe enough to prevent learning.

[Young patients with severe mental illness returning to school: results of a pilot project conducted in Montreal]

Schizophrenia generally appears at the beginning of adult life at a time when individuals have important academic choices to make for their professional future. Patients with schizophrenia suffer from cognitive deficits as well as positive and negative symptoms and experience disorganization. Schizophrenia is responsible for a high level of failure in obtaining a high school diploma, an important cause of social exclusion and low economic status. Twenty-seven students with severe mental health have been integrated in an educational program implemented in Montreal. Preliminary results indicate efficiency of the program with many students succeeding ministerial test. However, it is suggested that a ratio of 1/10 professor/students would be preferable in such special education class.

Happy birthday neuroleptics! 50 years later: la folie du doute

Given that we are celebrating the 50th birthday of neuroleptics introduction in psychiatry, the author proposes to take a look at certain results related to therapeutic practice. After a brief chronological literature review of the clinical practices and theoretical models that have controlled drug treatment of schizophrenia, the author presents a critical review of four meta-analyses. Since Delay, Deniker and Harl's initial report, the story of neuroleptics comprises several periods. In 1963, the hyper-dopaminergic theory of psychoses was proposed. Another period began with models mainly based on the serotonin/dopamine relative blockade receptor hypothesis. More recently, a new framework to understand the differential effect of antipsychotics is related to the appropriate modulation (e.g., fast dissociation) of the D2 receptor alone. The concept of atypicality has become a new vista for research and to market new compounds. However, after 50 years of neuroleptic drugs, are we able to answer the following simple questions: Are neuroleptics effective in treating schizophrenia? Is there a difference between atypical and conventional neuroleptics? How do the efficacy and safety of newer antipsychotic drugs compare with those of clozapine? Actually, the answers yielded by these simple questions by meta-analysis should elicit in us a good deal of humility. If we wish to base psychiatry on evidence-based medicine, we run a genuine risk in taking a closer look at what has long been considered fact. Each psychiatrist must continue to be critical, sceptical, optimistic (not overoptimistic) and to learn in order to integrate the positive aspects of our growing knowledge base.

Cerebral activity associated with auditory verbal hallucinations: a functional magnetic resonance imaging case study

Among the many theories that have been advanced to explain the mechanism by which auditory verbal hallucinations (AVH) arise, 2 that have received a degree of empirical support are: the hypothesis that AVHs arise from misinterpreted inner speech and the proposal that they arise from aberrant activation of the primary auditory cortex. To test these hypotheses, we were fortunate to be able to study the interesting and rare case of a woman with schizophrenia who experienced continuous AVH which disappeared when she listened to loud external speech. Functional magnetic resonance imaging (fMRI) was used to measure the patient's brain activity in the temporal and inferior frontal regions during the AVHs and while the she was listening to external speech. The brain activity of a matched control subject was also recorded under the same experimental conditions. AVHs were associated with increased metabolic activity in the left primary auditory cortex and the right middle temporal gyrus. Our results suggest a possible interaction between these areas during AVHs and also that the hypotheses of defective internal monitoring and aberrant activation are not mutually exclusive. Potential limitations to the generalization of our results are discussed.

Behavioral disorganization in schizophrenia during a daily activity: the kitchen behavioral scoring scale

Executive dysfunction has been extensively described in schizophrenia and has been found to correlate with the negative symptoms of the disease. However, executive dysfunction is usually assessed by cognitive tests, and these are not necessarily good predictors of an individual's daily functioning. This study aimed to discover whether executive dysfunction in schizophrenia can be measured by analyzing a daily routine such as cooking a meal. Behavior was scored on the basis of the optimal sequence of macrostructures (order of dishes) and microsteps (order of actions) that must be performed to prepare the meal in a minimum of time and with the smallest delay between the completion of the first and last dishes. The results showed that patients with schizophrenia make macrostructure but not micro-step sequencing errors. The number of repetitions and omissions and the delay between the completion of the first and last dish were all greater in patients than in control subjects. In patients with schizophrenia, but not in normal controls, these behavioral malfunctions were significantly correlated with both negative symptoms and performance on the executive tasks. Poor performance on the memory tests was not correlated with the behavioral malfunction. Therefore, daily functioning in schizophrenia may be specifically influenced by executive dysfunction in schizophrenia, and this can be quantitatively assessed with a behavioral scale of action sequences.