Do specific neurocognitive deficits predict specific domains of community function in schizophrenia?

Measurement and Treatment Research to Improve Cognition in Schizophrenia: NIMH MATRICS initiative to support the development of agents for improving cognition in schizophrenia

The impairments in social and vocational outcome that are common in schizophrenia are strongly related to the severity of impaired neurocognition. This observation led to the initiation of The NIMH's Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative, which supports the development of pharmacological agents to improve cognition in schizophrenia. MATRICS addresses barriers to drug development through a number of activities, including the development of a consensus battery for measuring cognition in schizophrenia; the development of a consensus regarding the most promising molecular targets that should be the focus of drug development; the use of a joint meeting with representatives from the industry, academia, NIMH, and the U.S. Food and Drug Administration (FDA) to clarify guidelines for the design of clinical trials for cognition enhancing agents; and finally, to assist NIMH in developing its research agenda in this area.

Longitudinal studies of cognition and functional outcome in schizophrenia: implications for MATRICS

It is generally accepted that cognitive deficits in schizophrenia are related to functional outcome. However, support for longitudinal relationships between cognition and functional outcome has not been as well documented. The current paper presents a review of 18 recently published longitudinal studies (minimum 6-month follow up) of the relationships between cognition and community outcome in schizophrenia. Results from these studies reveal considerable support for longitudinal associations between cognition and community outcome in schizophrenia. These studies demonstrate that cognitive assessment predict later functional outcome and provide a rationale for psychopharmacological interventions for cognitive deficits in schizophrenia. Although the relationships between cognition and community outcome are well-supported, it is clear that community functioning is also affected by a host of factors apart from cognition that are usually not considered in clinical trial studies (e.g., psychosocial rehabilitation and educational/vocational opportunities). In the second part of the paper, we consider intervening steps between cognitive performance measures and community outcome. These steps are apt to have important implications for clinical trials of cognition-enhancing agents in schizophrenia.

Neurocognitive functioning and quality of life among dually diagnosed and non-substance abusing schizophrenia inpatients

The aim of this study was to compare the domains of intellectual, memory and executive functions of persons with schizophrenia who concurrently have substance abuse disorders (the dually diagnosed) with a group of non-substance-abusing patients with schizophrenia and to ascertain if there were differences between the two groups in their perceptions of quality of life. Neuropsychological and quality of life data of 46 dually diagnosed and 43 non-substance-abusing patients with schizophrenia was analysed retrospectively. All subjects were inpatients of a state psychiatric hospital. Selected subtests of the Wechsler Adult Intelligence Scale-III and the Wechsler Memory Scale-III constituted the intellectual and memory measures whilst the measures of executive functioning were the Stroop Color Word Test, the FAS version of the Controlled Oral Word Association Test, and the Trail Making Test (Trails A & B). Perceptions of quality of life were evaluated using the World Health Organization Quality of Life measure. The two groups did not differentiate on intellectual and memory domains, however, the dually diagnosed showed a significantly better facility with tasks of executive functions. In addition, the dually diagnosed expressed higher levels of satisfaction with their quality of life compared to the non-substance-abusing patients with schizophrenia. These results have implications for interventions.

A brief cognitive assessment for use with schizophrenia patients in community clinics

Cognitive impairment is a prominent feature of schizophrenia. The availability of very brief measures may increase the use of cognitive assessment in routine care settings. We examined the reliability and validity of the brief cognitive assessment (BCA), a battery that takes approximately 15 min to administer and score, and that was designed to be sensitive to changes in cognition with novel antipsychotics. The BCA was administered to 340 outpatients on two occasions, 3 months apart. A sub-sample of subjects received a full battery of cognitive tests (n=97) and additional measures of functional outcome. Results indicated that the BCA had very good test-retest reliability and inter-item consistency. Moreover, the BCA was strongly correlated with a comprehensive battery (r=0.72; p<0.0001) which took 8 to 10 times longer to administer. Finally, both cognitive batteries were correlated similarly with measures of community functioning. Changes over time for individual patients can be interpreted in the context of normative data available for each test in the BCA. The data provide preliminary evidence for the reliability and validity of the BCA. Further studies examining the utility of the BCA for tracking changes in cognitive functioning with treatment are encouraged.

Retour à l’école de jeunes patients souffrant de troubles mentaux graves : premier regard sur un projet pilote montréalais

La schizophrénie se manifeste habituellement au début de l’âge adulte au moment où l’individu fait face à des responsabilités scolaires décisives pour son orientation professionnelle. Les patients souffrant de schizophrénie présentent des déficits cognitifs, des symptômes positifs, négatifs, et de désorganisation. La schizophrénie est responsable d’un taux d’échec élevé dans l’atteinte d’étude secondaire, ce qui contribue à renforcer l’exclusion sociale et à réduire l’atteinte des objectifs socio-économiques. Vingt-sept élèves souffrant de maladie mentale ont pu bénéficier d’un programme de réadaptation scolaire implanté à Montréal. Les résultats préliminaires mettent en évidence l’efficacité du programme puisque plusieurs élèves ont réussi des examens du ministère. Toutefois, ces résultats suggèrent qu’un ratio professeur/élèves de 1/10 serait préférable dans ces classes spécialisées.

Demographic, clinical, and neurocognitive predictors of quality of life in schizophrenia patients receiving conventional neuroleptics

We sought to evaluate demographic, clinical, and neurocognitive predictors of self-rated life quality and hospitalization in schizophrenia patients without the potentially cognition-enhancing influence of newer generation neuroleptic medication. A sample of 55 atypical neuroleptic-naive schizophrenia patients was assessed at index and 3 years later. Index neurocognitive measures included general intellectual ability (IQ), executive ability (Wisconsin Card Sorting Test [WCST]), verbal memory (California Verbal Learning Test [CVLT]), and manual dexterity (Purdue Pegboard). These measures, along with demographic (age, sex, education) and clinical (symptoms, prior hospitalizations) variables, were entered into regression equations to predict life quality (Sickness Impact Profile [SIP]) at follow-up, as well as rehospitalization during the 3-year period. Stability data were also analyzed. Demographic and cognitive data predicted subjective quality of life, but not rehospitalization. Changes in memory over time rather than performance levels related to life quality at follow-up. Rehospitalization was related only to demographic data and previous hospital admissions. The findings support the predictive value of selected aspects of neurocognition in relation to a subjective outcome domain in schizophrenia.

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.

Memory and attention performance in psychiatric patients: lack of correspondence between clinician-rated and patient-rated functioning with neuropsychological test results

In the present study, the correspondence between clinician-assessed and self-reported neurocognitive performance was contrasted with scores obtained from psychometric neuropsychological tests in 148 psychiatric in-patients. Results revealed that self-reported cognitive functioning was strongly associated with depressive symptomatology but was only poorly related to psychometric neurocognitive performance, particularly in schizophrenia. After illness denial was controlled for, the overall association between subjective and objective test performance was slightly increased but still failed to reach significance in six out of eight analyses. In approximately 20% to 40% of all cases, clinicians judged memory performance to be normal despite substantial impairment revealed by neuropsychological test results (attention parameters: 7-51%). Since (ecological) validity and reliability have been demonstrated for many neurocognitive paradigms, the present results question the validity of non-psychometric neurocognitive assessment and call for a complementation of clinical judgment with neurocognitive assessment. Reasons for decreased sensitivity of self-reported and clinician-assessed neurocognitive functioning are discussed.

Serotonin receptors represent highly favorable molecular targets for cognitive enhancement in schizophrenia and other disorders

RATIONALE

Current treatments for schizophrenia adequately treat the positive symptoms of schizophrenia but only modestly improve cognitive deficits. This review provides evidence for and against the use of selective 5-HT receptor drugs as cognition enhancing agents for schizophrenia and other disorders.

METHODS

Pre-clinical and clinical literature concerned with the role of the serotonergic system in cognition and memory as it relates to schizophrenia is reviewed. Individual 5-HT receptor subtypes for which selective drugs are available that are likely to improve cognition are reviewed. Recommendations for clinical testing are proposed.

RESULTS AND CONCLUSIONS

Four 5-HT receptor systems (5-HT(1A), 5-HT(2A), 5-HT(4), 5-HT(6)) are highlighted as suitable targets for enhancing cognition and memory. Because many clinically available antipsychotic drugs already target 5-HT(1A), 5-HT(2A) and 5-HT(6) receptors, design of clinical trials will need to take into account the serotonergic pharmacology of concurrently administered antipsychotic medications. 5-HT(1A) partial agonists and 5-HT(2A) antagonists have shown modest effectiveness in improving cognition in schizophrenia. 5-HT(6)-selective compounds for cognition enhancement are in late-stage clinical trials, while 5-HT(4) compounds have not yet been tested in humans for cognition enhancement.

RECOMMENDATIONS

For stand-alone therapy for enhancing cognition, 5-HT(1A) partial agonists, 5-HT(2A) antagonists, 5-HT(4) partial agonists and 5-HT(6) antagonists are all likely to induce at least modest improvement in cognition in schizophrenia. If "add-on therapy" is contemplated, antipsychotic drugs with weak affinities for serotonin receptors should be used to avoid confounds. It is likely that serotonergic drugs will soon be available as cognition enhancing medications for disorders other than schizophrenia (e.g. dementia).

General and specific cognitive deficits in schizophrenia

BACKGROUND

It is controversial whether the cognitive deficit in schizophrenia is better characterized as generalized or as reflecting relatively independent deficits in different cognitive domains. The issue has implications for assessment practice, intervention design, and the exploration of schizophrenia genetics.

METHODS

We used a specialized structural equation modeling approach, single common factor analysis, to explore the relative importance of generalized versus independent cognitive deficits in schizophrenia. Eighteen subtest scores from the Wechsler Adult Intelligence Scale-III and the Wechsler Memory Scale-III were included in the analysis. We analyzed these data for 97 schizophrenia or schizoaffective disorder outpatients and 87 healthy control subjects.

RESULTS

Approximately two thirds of the overall effect of a schizophrenia diagnosis on cognitive performance was mediated through a single common factor. The Wechsler subtest scores showed almost uniformly strong relationships with this factor. The independent associations of group status with the subtest scores were smaller in magnitude and only selectively significant.

CONCLUSIONS

The relatively greater magnitude of illness effects mediated through the common factor in this analysis, compared with the specific, independent effects, suggests that a generalized cognitive deficit is a core feature of schizophrenia.

Zusammenhänge zwischen Veränderungen in verschiedenen Funktionsbereichen von schizophren Erkrankten während der Durchführung sozialer Fertigkeitstrainings

Zusammenfassung. Theoretischer Hintergrund: Auf Grund einer Übersicht bisheriger Befunde schlugen Green und Nuechterlein (1999) ein Modell vor, welches das Zusammenwirken zwischen verschiedenen Funktionsbereichen schizophren Erkrankter beschreibt. Fragestellung: Die vorliegende explorative Studie untersucht, ob sich Zusammenhänge zwischen Veränderungen im kognitiven und sozialen Bereich sowie der Symptomatik schizophren Erkrankter während der Durchführung sozialer Fertigkeitstrainings ergeben und inwiefern diese dem von Green und Nuechterlein vorgeschlagenen Modell entsprechen. Methode: 80 Patienten, die an einem sozialen Fertigkeitstraining teilgenommen hatten, wurden in die Auswertung einbezogen. Als hauptsächliche Auswertungsmethode wurde der “typologische“ Ansatz zur Veränderungsmessung von Schöttke et al. (1993) verwendet. Ergebnisse: Signifikante Zusammenhänge ergaben sich zwischen den Veränderungen in der Aufmerksamkeitsleistung, der Negativsymptomatik und dem sozialen Funktionsniveau. Die Veränderungen in der Positivsymptomatik zeigten sich von den Veränderungen in den restlichen Bereichen als unabhängig. Schlussfolgerungen: Die Ergebnisse entsprechen weitgehend den bisherigen Befunden und in diesem Sinne dem von Green & Nuechterlein vorgeschlagenen Modell. Eine mögliche Bedeutung dieser Ergebnisse für die differenzielle Indikation in der psychosozialen Behandlung schizophren Erkrankter wird diskutiert.

The impact of antipsychotics on psychomotor performance with regards to car driving skills

Cognitive and psychomotor impairments are a core feature of most patients with schizophrenia and may have an important influence on driving ability. The present study investigated the effects of neuroleptic monotherapy on psychomotor functions related to car driving skills in schizophrenic patients. Consecutively admitted schizophrenic inpatients (n = 120) were tested under steady state plasma level conditions before discharge to outpatient treatment. Patients met the International Classification of Diseases, Tenth Revision criteria for schizophrenia. The study followed a naturalistic nonrandomized design. Data were collected with the computerized Act & React Testsystem and were analyzed according to medication, severity of illness, and age. Only 32.5% of the schizophrenic inpatients passed the tests without major impairments. Patients treated with atypical neuroleptics or clozapine showed a better test performance on skills related to driving ability when compared with patients on typical neuroleptics. Differences were most pronounced in measures of divided attention, stress tolerance, and attention. Data also suggest that treatment with clozapine had an overall positive impact on measures of reactivity and stress tolerance. These results show that even under steady state pharmacologic conditions psychomotor functions of most schizophrenic patients partly remitted must be considered as impaired. To evaluate these effects, a systematic neuropsychologic examination is recommended.

Benefits of Adjunct Modafinil in an Open-Label, Pilot Study in Patients With Schizophrenia

Patients with schizophrenia experience cognitive impairments associated with hypofunctioning of the frontal cortex. Modafinil, a novel wake-promoting agent, works through the sleep-wake centers of the brain to activate the cortex. This 4-week, open-label, pilot study evaluated adjunct modafinil in patients with schizophrenia or schizoaffective disorder. Eleven patients received once-daily oral doses of modafinil (100 mg/day, days 1-14; 100 or 200 mg/day, days 15-28) in addition to antipsychotic therapy. Modafinil significantly improved patients' global functioning as assessed by a blinded clinician (week 2, P = 0.026; week 4, P = 0.012) and the investigator (week 3, P = 0.035). Modafinil significantly improved overall clinical condition, with 64% and 82% of patients rated as clinically improved at week 4 by a blinded clinician and the investigator respectively. Eighty-nine percent of patients considered themselves to be clinically improved. Modafinil significantly improved fatigue (P = 0.025, week 3) and tended to improve cognitive functioning scores. Control of positive symptoms was well maintained. Treatment-emergent adverse events included dry mouth (n = 2) and hallucinations (n = 2). One patient discontinued the study because of hallucinations that were considered to be possibly related to inadequate antipsychotic therapy. Although preliminary, these results suggest modafinil may be an effective and well-tolerated adjunct treatment that improves global functioning and clinical condition, and reduces fatigue in patients with schizophrenia or schizoaffective disorder. Additional controlled studies are warranted.

Profiles of neuropsychologic function in schizophrenia

In this article, the author reviews basic neuropsychologic issues in the study of schizophrenia. The first issue is whether cognitive dysfunction reflects a degenerative process or is a core feature of the disorder. Evidence demonstrating that cognitive difficulties are present at illness onset and are not caused by medication, illness progression, or other nonspecific factors is reviewed. The second question is less easily answered and deals with whether cognitive difficulties represent generalized dysfunction or differential deficits in specific neurocognitive domains. One difficulty in answering this question is the heterogeneous nature of the disorder. Clinical and cognitive subtyping approaches to reducing heterogeneity are discussed, with the conclusion that cognitive approaches hold the most promise for understanding subtype differences in neurobiologic substrates. Finally, the relation of cognitive ability to functional outcome is described, and it is explained why there is a resurgent interest in remediation efforts. The article closes with suggestions for future directions.

Prevalence of executive impairment in patients seen by a psychiatry consultation service

The prevalence of impairment of executive function among 50 medical inpatients referred for psychiatric consultation was assessed by using the Executive Interview (EXIT25) and an executive clock-drawing task (CLOX). The Mini-Mental Status Examination (MMSE) was also administered to assess general cognition. The percentage of patients who failed each test was calculated. Seventy-two percent failed at least one measure of executive function, whereas only 30% failed the MMSE. The results suggest that impairment of executive function is common among inpatients referred for psychiatric consultation. Because impairment of executive function has been specifically associated with behavioral and functional disability, routine assessment of executive function should be integrated into psychiatric case management.

Social cognition and neurocognitive deficits in schizophrenia

While research equivocally supports a relationship between social cognition and neurocognition, it is less clear whether social cognition is related to general cognitive functioning or whether specific aspects of social cognition are linked with specific forms of neurocognition. Thus, this study sought to investigate the relationships between various domains of neurocognition and two forms of social cognition, social cue recognition and social problem solving, for 40 people with schizophrenia spectrum disorders. Step-wise multiple regressions found that performance on neurocognitive tests was able to predict 47% and 38% of the variance on measures of the ability to recognize actual and suggested social cues, respectively, and 13% of participants' ability to problem solve in ambiguous social situations. Once estimated intelligence and hospitalization history were controlled, however, neurocognition no longer significantly predicted social problem solving. Executive functioning was uniquely related to each type of social cue recognition, while memory predicted only the recognition of concrete social cues.

The relationship of neuropsychological abilities to specific domains of functional capacity in older schizophrenia patients

BACKGROUND

This study sought to determine the relative importance of cognitive measures in predicting various domains of everyday functional capacity in older outpatients with schizophrenia.

METHODS

Ninety-three psychiatry outpatients with diagnoses of schizophrenia and schizoaffective disorders underwent a comprehensive neuropsychiatric evaluation, including neuropsychological testing and clinical ratings of psychopathology. Functional capacity was assessed with the Direct Assessment of Functional Status, a performance measure of basic and instrumental activities of daily living (ADLs/IADLs).

RESULTS

Neuropsychological performance significantly predicted most ADLs/IADLs measured, except simple eating behaviors, time orientation, and grooming. Lower educational level and negative symptoms also were associated with worse functional capacity, whereas positive symptoms and depressed mood were not. Measures of cognitive functioning accounted for more variance in functional capacity than did psychiatric ratings of symptoms, and multiple regression analyses demonstrated that neuropsychological performance was predictive of functional capacity, over and above clinical symptoms. No specific cognitive domains were differentially predictive of specific domains of functional capacity.

CONCLUSIONS

Neurocognitive abilities were more predictive of functional capacity than level of clinical symptoms; however, these abilities were not specific predictors of functioning. This is consistent with findings of relatively generalized, intercorrelated cognitive impairment in schizophrenia and multiply determined domains of everyday functioning.

The relations between cognition and the independent living skill of shopping in people with schizophrenia

A great deal of interest has developed regarding the impact of cognitive deficits on the everyday functioning of people with schizophrenia. This study examined the relationships between cognitive functioning and the performance of a specific independent living skill (grocery shopping) in a sample of 73 individuals with schizophrenia or schizoaffective disorder. Cognitive variables included tests of verbal memory, executive functioning, verbal fluency, sustained attention and visual motor skill. Functional outcome was measured with the Test of Grocery Shopping Skills, which is an ecologically based performance measure that requires participants to shop for 10 items within an actual grocery store. Accuracy on the shopping task was significantly associated with fewer perseverative responses on the Wisconsin Card Sorting Test, better verbal memory and faster processing speed. Shopping efficiency (i.e. less redundancy) was associated with better performance on several cognitive tasks, including verbal memory, verbal fluency, sustained attention and executive functioning. Results of this study extend previous research by examining the relation between cognition and the actual performance of daily living skills under natural circumstances.

Neuropsychological profiles delineate distinct profiles of schizophrenia, an interaction between memory and executive function, and uneven distribution of clinical subtypes

Neuropsychological performance in 151 patients with schizophrenia was examined using cluster analysis to identify neurocognitive subtypes. Hierarchical and iterative partitioning methods identified four clusters using an extended neuropsychological battery. Consistent with previous findings two extreme clusters were characterized by near normative performance and profound global dysfunction, respectively. The two remaining neurocognitive clusters displayed moderate-severe dysfunction and were differentiated by unique patterns of abstraction and flexibility, attention, spatial memory, and sensory-perception. Analysis of variance revealed an interaction between global memory and executive function for clusters III and IV. Although limited cluster differences were found relative to clinical and historical data, the distribution of previously defined clinical subtypes was uneven among neurocognitive clusters. Paranoid patients were significantly more likely to be classified into cluster II and disproportionately absent from clusters I and IV. Patients with negative and disorganized clinical subtypes comprised a disproportionate component of clusters I and IV but were less likely to be classified in cluster II. This suggests greater correspondence than previously postulated between systems responsible for clinical symptomatology and those moderating neurocognitive dysfunction.

Independence and overlap among neurocognitive correlates of community functioning in schizophrenia

Existing literature on the neurocognitive correlates of community functioning in schizophrenia has not adequately focused on the relationships among the correlated variables. In a sample of 40 outpatients with schizophrenia and related disorders, we studied two sets of variables that we expected to be related to broad ratings of community functioning: (1) the Wechsler Adult Intelligence Scale-III (WAIS-III) index scores for verbal comprehension, perceptual organization, working memory, and processing speed; and (2) positive, negative, disorganized and affective symptom variables. Of the WAIS-III index scores, working memory and processing speed entered a stepwise regression, together accounting for substantial variance in functional ratings (R(2)=0.37). However, only processing speed remained significantly associated with community functioning after controlling for the other indexes. In relation to community functioning, the remaining indexes appeared to be overlapping markers of general cognitive ability, rather than specific measures of discrete cognitive domains. Addition of positive and negative symptom variables in a further analysis greatly increased the explained functional variance (R(2)=0.65). Processing speed overlapped substantially with negative symptoms in predicting functioning, while the other WAIS-III indexes were independent of symptomatology. Results illustrate the importance of (1) knowing which neurocognitive variables have specific relationships to community functioning and which reflect the influence of more general cognitive ability in daily life, and (2) appreciating areas of overlap and independence among classes of correlates of functioning, such as neurocognitive and symptom variables. This improved understanding has implications for predictive models of community functioning, for cognitive rehabilitation and deficit compensation strategies, and for assessment practice.

Executive control function in psychiatric and medical illness

Executive Control Function (ECF) is the ability to plan, sequence, and monitor one's behavior in order to accomplish a given goal while simultaneously exercising cognitive flexibility to adapt to changing task requirements. Multiple studies demonstrate that ECF predicts functional outcome, level of care required, and work potential for both well and ill populations. However, clinicians often do not routinely assess ECF during mental status evaluations because of the perceived lack of practical bedside tests. This review article discusses the major neuropsychological measures used to probe for impairment, with special emphasis on those that are easily administered at the patient's bedside. The current literature on executive dysfunction in psychiatric and medical illness is reviewed. The neuroanatomy and neurochemistry of ECF is also reviewed, with emphasis on structural dysfunction in specific illnesses. Finally, various treatment options, both pharmacological and psychotherapeutic, are discussed.

Cognition in schizophrenia

Cognitive dysfunction has been described as a hallmark feature of schizophrenia since the first descriptions of the illness. Kraepelin described a number of features of the disorder that he thought reflected impairments in cognition and attention. He also speculated that cognitive impairments were mediated by neurobiologic dysfunction, specifically impairments in the functions of the frontal lobe. Since Kraepelin's time, there have been many changes in the general conceptions of schizophrenia, including ideas regarding the status and importance of cognitive impairment in the illness. Due to increased sophistication of neuropsychologic assessment and neuroimaging techniques, cognitive impairment has again has risen to the forefront of importance in terms of theories regarding the etiology and treatment of schizophrenia.