Neuropsychological practice effects and change detection in people with schizophrenia

A longitudinal comparison of two neurocognitive test batteries in patients with schizophrenia and healthy volunteers: Time effects on neuropsychological performance and their relation to functional outcome

Cognitive impairment is a major unmet need in the treatment of schizophrenia. Over the last decade, the MATRICS Consensus Cognitive Battery (MCCB) has been used to assess the effects of novel treatments for cognitive impairment in schizophrenia. However, other cognitive-neuroscience-based cognitive batteries, such as the Cambridge Neuropsychological Test Automated Battery (CANTAB) have been suggested as an alternative to the MCCB. Although both batteries purport to assess cognitive function in psychosis, no previous study has attempted to examine their validity longitudinally and the potential overlap between the two batteries over time. The aim of the current study was to assess the relationship between the MCCB and the CANTAB in the longitudinal assessment of cognitive impairment in schizophrenia. A sample of 39 stable schizophrenia outpatients and 18 controls completed the MCCB and the CANTAB battery at baseline, and at 2, 4 and 8-weeks follow-up. Correlation analyses and a mixed-model repeated measures approach were used. We found no significant effect of time in the MCCB. In contrast, for the CANTAB a significant effect of time consistent with practice effects for the attention domain in the control group and for the visual learning, reasoning and problem-solving, and social cognition domains in patients, with subjects performing better at follow-up. In particular, a significant time ∗ battery interaction was found for those cognitive domains. These findings suggest there are specific differences across cognitive tests to assess cognitive impairments in schizophrenia and that measures derived from the CANTAB appear to be more prone to practice effects in these patients.

Psychometric characteristics of the MATRICS Consensus Cognitive Battery in a large pooled cohort of stable schizophrenia patients

The MATRICS Consensus Cognitive Battery (MCCB) was developed to assess cognitive treatment effects in schizophrenia clinical trials, and is considered the FDA gold standard outcome measure for that purpose. The aim of the present study was to establish pre-treatment psychometric characteristics of the MCCB in a large pooled sample. The dataset included 2616 stable schizophrenia patients enrolled in 15 different clinical trials between 2007 and 2016 within the United States (94%) and Canada (6%). The MCCB was administered twice prior to the initiation of treatment in 1908 patients. Test-retest reliability and practice effects of the cognitive composite score, the neurocognitive composite score, which excludes the domain Social Cognition, and the subtests/domains were examined using Intra-Class Correlations (ICC) and Cohen's d. Simulated regression models explored which domains explained the greatest portion of variance in composite scores. Test-retest reliability was high (ICC=0.88) for both composite scores. Practice effects were small for the cognitive (d=0.15) and neurocognitive (d=0.17) composites. Simulated bootstrap regression analyses revealed that 3 of the 7 domains explained 86% of the variance for both composite scores. The domains that entered most frequently in the top 3 positions of the regression models were Speed of Processing, Working Memory, and Visual Learning. Findings provide definitive psychometric characteristics and a benchmark comparison for clinical trials using the MCCB. The test-retest reliability of the MCCB composite scores is considered excellent and the learning effects are small, fulfilling two of the key criteria for outcome measures in cognition clinical trials.

Social cognition psychometric evaluation (SCOPE) in people with early psychosis: A preliminary study

Social cognition is an important outcome in schizophrenia research. Unfortunately, there has been a lack of consensus regarding which measures of social cognition best capture this domain of functioning. The Social Cognition Psychometric Evaluation (SCOPE) study was developed to address the need for a battery of measures that have sound psychometric properties and can be implemented in clinical trials for individuals with chronic schizophrenia. The current study expands upon the SCOPE study by examining the psychometric properties of the eight candidate measures administered to individuals early in the course of psychosis. Thirty-eight stable outpatients with first episode psychosis and thirty-nine healthy controls completed the battery at baseline and one-month follow-up assessments. The SCOPE battery was evaluated on a collection of psychometric properties, including: (1) Reliability - including test-retest and internal consistency, (2) Between group differences, (3) Utility as a repeated measure, (4) Relationship to social and occupational functioning, (5) Incremental validity - variance in functioning beyond neurocognition, and (6) Feasibility - including practicality of administration and tolerability. Social cognition accounted for substantially more variance in functional outcome than neurocognition. Only one measure, the Hinting task, displayed adequate psychometric properties to be recommended for use in clinical research with first episode psychosis. The remaining candidate measures would require modifications before implementation or cannot be recommended for use in clinical research with first episode psychosis.

Adjunctive memantine in clozapine-treated refractory schizophrenia: an open-label 1-year extension study

BACKGROUND

In a recent placebo-controlled, double-blind crossover trial (n = 52), significant beneficial effects on memory (d = 0.30) and negative symptoms (d = 0.29) were found after 12 weeks of memantine augmentation in patients with clozapine-refractory schizophrenia. In this open-label 1-year extension study we report the long-term effects and tolerability of memantine add-on therapy to clozapine.

METHOD

Completers of the first trial who experienced beneficial effects during 12 weeks of memantine treatment received memantine for 1 year. Primary endpoints were memory and executive function using the Cambridge Neuropsychological Test Automated Battery, the Positive and Negative Syndrome Scale (PANSS), and the Clinical Global Impression Severity Scale (CGI-S).

RESULTS

Of 31 randomized controlled trial completers who experienced beneficial effects from memantine, 24 received memantine for 1 year. The small improvement in memory found in the memantine condition in the placebo-controlled trial remained stable in the extension study. Executive function did not improve. After 26 weeks of memantine add-on therapy to clozapine, PANSS negative symptoms (r = 0.53), PANSS positive symptoms (r = 0.50) and PANSS total symptoms (r = 0.54) significantly improved. Even further significant improvement in all these measures was observed between 26 weeks and 52 weeks of memantine, with effect sizes varying from 0.39 to 0.51. CGI-S showed a non-significant moderate improvement at 26 weeks (r = 0.36) and 52 weeks (r = 0.34). Memantine was well tolerated without serious adverse effects.

CONCLUSIONS

In the 1-year extension phase the favourable effect of adjunctive memantine on memory was sustained and we observed further improvement of negative, positive and overall symptoms in patients with clozapine-treated refractory schizophrenia.

Visual-spatial memory may be enhanced with theta burst deep brain stimulation of the fornix: a preliminary investigation with four cases

Memory loss after brain injury can be a source of considerable morbidity, but there are presently few therapeutic options for restoring memory function. We have previously demonstrated that burst stimulation of the fornix is able to significantly improve memory in a rodent model of traumatic brain injury. The present study is a preliminary investigation with a small group of cases to explore whether theta burst stimulation of the fornix might improve memory in humans. Four individuals undergoing stereo-electroencephalography evaluation for drug-resistant epilepsy were enrolled. All participants were implanted with an electrode into the proximal fornix and dorsal hippocampal commissure on the language dominant (n = 3) or language non-dominant (n = 1) side, and stimulation of this electrode reliably produced a diffuse evoked potential in the head and body of the ipsilateral hippocampus. Each participant underwent testing of verbal memory (Rey Auditory-Verbal Learning Test), visual-spatial memory (Medical College of Georgia Complex Figure Test), and visual confrontational naming (Boston Naming Test Short Form) once per day over at least two consecutive days using novel test forms each day. For 50% of the trials, the fornix electrode was continuously stimulated using a burst pattern (200 Hz in 100 ms trains, five trains per second, 100 µs, 7 mA) and was compared with sham stimulation. Participants and examiners were blinded to whether stimulation was active or not, and the order of stimulation was randomized. The small sample size precluded use of inferential statistics; therefore, data were analysed using descriptive statistics and graphic analysis. Burst stimulation of the fornix was not perceived by any of the participants but was associated with a robust reversible improvement in immediate and delayed performance on the Medical College of Georgia Complex Figure Test. There were no apparent differences on either Rey Auditory-Verbal Learning Test or Boston Naming Test. There was no apparent relationship between performance and side of stimulation (language dominant or non-dominant). There were no complications. Preliminary evidence in this small sample of patients with drug-resistant epilepsy suggests that theta burst stimulation of the fornix may be associated with improvement in visual-spatial memory.

Practice effects due to serial cognitive assessment: Implications for preclinical Alzheimer's disease randomized controlled trials

Introduction

Practice effects are characteristic of nearly all standard cognitive tasks when repeated during serial assessments and are frequently important confounders in clinical trials.

Methods

We summarize evidence that gains in neuropsychological test performance scores associated with practice effects occur as artifactual changes associated with serial testing within clinical trials. We identify and emphasize such gains in older, non–cognitively impaired individuals and estimate an effect size of 0.25 for composite cognitive measures in older populations assessed three times in a 6- to 12-month period.

Results

We identified three complementary approaches that can be used to attenuate practice effects: (1) massed practice in a prebaseline period to reduce task familiarity effects; (2) tests designed to reduce practice-related gains so that item-specific driven improvements are minimized by using tasks that minimize strategy and/or maximize interitem interference; and (3) well-matched alternate forms.

Discussion

We have drawn attention to and increased awareness of practice effect–related gains that could result in type 1 or type 2 errors in trials. Successfully managing practice effects will eliminate a large source of error and reduce the likelihood of misinterpretation of clinical trials outcomes.

Blueberry supplementation improves memory in older adults

The prevalence of dementia is increasing with expansion of the older adult population. In the absence of effective therapy, preventive approaches are essential to address this public health problem. Blueberries contain polyphenolic compounds, most prominently anthocyanins, which have antioxidant and anti-inflammatory effects. In addition, anthocyanins have been associated with increased neuronal signaling in brain centers, mediating memory function as well as improved glucose disposal, benefits that would be expected to mitigate neurodegeneration. This study investigated the effects of daily consumption of wild blueberry juice in a sample of nine older adults with early memory changes. At 12 weeks, improved paired associate learning (p = 0.009) and word list recall (p = 0.04) were observed. In addition, there were trends suggesting reduced depressive symptoms (p = 0.08) and lower glucose levels (p = 0.10). We also compared the memory performances of the blueberry subjects with a demographically matched sample who consumed a berry placebo beverage in a companion trial of identical design and observed comparable results for paired associate learning. The findings of this preliminary study suggest that moderate-term blueberry supplementation can confer neurocognitive benefit and establish a basis for more comprehensive human trials to study preventive potential and neuronal mechanisms.

Changes in neurocognitive function in patients with schizophrenia after starting or switching to amisulpride in comparison with the normal controls

We examined short- and long-term changes in neurocognitive functions in patients with schizophrenia who were either started or switched to amisulpride in comparison with the normal controls. Fifty-seven patients treated with amisulpride and 60 normal controls completed a comprehensive neurocognitive function test battery at the baseline, the 8-week, and the 1-year follow-up. We conducted and compared the results of both intention-to-treat (ITT) and per-protocol (PP) analyses to account for the follow-up loss. Three general results obtained were as follows: (1) the degree of the improvements in neurocognitive function was comparable to those of other second-generation antipsychotics in both ITT and PP analysis; (2) in light of the relative effect size, the composite effect size and the effect size in most measures in both ITT and PP analyses were smaller for the patient group than those of the control group, signifying that improvement in performance may be largely attributable to practice effects; and (3) nonetheless, there were evidences of both short- and long-term improvements in some cognitive tasks, such as in the Korean-Wechsler Adult Intelligence Scale vocabulary subtest and the Trail Making Test, that may not be accounted by practice effect. These results suggest the need to include a healthy control group to validate the medication effect of cognitive improvements in patients with schizophrenia and to consider practice effect in interpreting the results of repeated administration of neurocognitive function tests.

Effect of buspirone, a serotonin1A partial agonist, on cognitive function in schizophrenia: a randomized, double-blind, placebo-controlled study

In previous studies, we demonstrated that tandospirone, a serotonin-5-HT1A partial agonist, added to ongoing treatment with small to moderate doses of typical antipsychotic drugs, improved executive function and verbal learning and memory. However, tandospirone is not available in most countries, and atypical antipsychotic drugs (AAPDs) have largely replaced typical antipsychotic drugs as the primary treatment for schizophrenia. Therefore, the goal of this randomly assigned placebo-controlled double-blind study was to determine if the addition of buspirone, a widely available 5-HT1A partial agonist, would enhance cognitive function, in subjects with schizophrenia treated with AAPDs. Seventy-three patients with schizophrenia, who had been treated with an AAPD for at least three months, were randomly assigned to receive either buspirone, 30 mg/day, or matching placebo. All other medications remained unchanged. Attention, verbal fluency, verbal learning and memory, verbal working memory, and executive function, as well as psychopathology, were assessed at baseline, and 6 weeks, and 3 and 6 months after baseline. A significant Time x Group interaction effect was noted on the Digit Symbol Substitution Test, a measure of attention/speeded motor performance, due to better performance of the buspirone group compared to the placebo group at 3 months. No significant interaction effects were noted for other domains of cognition. Scores on the Brief Psychiatric Rating Scale (Total, Positive) were improved during treatment with buspirone but not placebo, but the effects did not reach statistical significance. The results of this study showed a possible benefit of buspirone augmentation of AAPDs to enhance attention. However, we did not replicate the results of the previous study with tandospirone, which may be due to the differences between tandospirone and buspirone, between typical antipsychotics and AAPDs, or a combination of the above. Further study to determine the usefulness of 5-HT1A agonist treatment in schizophrenia is indicated.

Dissociating medication effects from learning and practice effects in a neurocognitive study of schizophrenia: Olanzapine versus haloperidol

OBJECTIVE

To contrast the effect of a typical antipsychotic (haloperidol) and an atypical antipsychotic (olanzapine) on neurocognitive functioning in schizophrenia when learning and practice (LP) effects are controlled.

METHODS

Two groups of participants were recruited, 27 schizophrenia patients in their first 5 years of illness and 13 normal controls. Prior to double-blind randomisation, all subjects were assessed on four occasions within 5 days (prerandomisation period) on the same neurocognitive battery. Repeated assessment prior to randomisation was chosen as a method to control for LP effects. Patients were then randomised to 56 days of treatment with haloperidol or olanzapine (postrandomisation). All subjects were assessed on neurocognitive measures at Days 28 and 56.

RESULTS

LP effects were present during the prerandomisation period on motor tasks, verbal and visual short-term memory, attention, and on a measure of verbal working memory. There were no changes in performance for patients randomised to treatment with olanzapine or haloperidol or the normal control group during the postrandomisation period.

CONCLUSIONS

Once LP effects are controlled, olanzapine and haloperidol do not affect performance on measures of motor functioning, verbal short-term memory, attention, verbal working memory, reaction time, visuospatial short-term memory, and visual working memory beyond that observed from LP effects.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Cognitive function does not worsen during pegylated interferon and ribavirin retreatment of chronic hepatitis C

Treatment of chronic hepatitis C with pegylated interferon (peginterferon) and ribavirin can cause or exacerbate depression but its effects on cognitive function are largely unknown. The aim of this study was to determine whether treatment with peginterferon and ribavirin adversely impacts cognitive function in patients with chronic hepatitis C. Prior nonresponders to interferon were retreated with peginterferon alfa-2a and ribavirin for 24 (n=177) or 48 weeks (n=57) in the Hepatitis C Antiviral Long-term Treatment Against Cirrhosis trial. Cognitive function was prospectively assessed using a battery of 10 standardized neuropsychological tests at weeks 0, 24, 48, and 72. Cognitive impairment was defined based upon a global deficit score. The Beck Depression Inventory and Brief Symptom Inventory were used to assess mood status. The 57 subjects who completed 48 weeks of antiviral therapy reported significant increases in difficulty concentrating, emotional distress, and symptoms of depression, all of which improved after cessation of therapy [P<0.0001, analysis of variance (ANOVA)]. Nonetheless, the frequency of cognitive impairment did not increase during the first 24 weeks of treatment in 177 patients (34% versus 32%, P=0.64) nor in the 57 patients completing 48 weeks of treatment (P=0.48, ANOVA).

CONCLUSION

Retreatment of prior non-responders with peginterferon and ribavirin was not associated with objective evidence of cognitive impairment as measured by a comprehensive battery of neuropsychological tests. The lack of cognitive impairment is reassuring and suggests that self-reported symptoms of cognitive dysfunction are more likely related to the systemic and psychiatric side effects of antiviral treatment rather than measurable changes in cognition.

The effect of verbalization strategy on Wisconsin Card Sorting Test performance in schizophrenic patients receiving classical or atypical antipsychotics

BACKGROUND

A number of reports showed en encouraging remediation in some patients' executive deficits thanks to the use of 'information processing strategies'. Moreover the impact of antipsychotics on cognitive functions of the schizophrenics is an important issue, especially if an integrated psychosocial treatment is needed. The aim of this paper is to evaluate different executive performance and response to verbalization, a strategy of the Wisconsin Card Sorting Test (WCST) remediation, in subjects on classical vs atypical antipsychotic (AP) treatment.

METHODS

Sixty-three schizophrenic subjects undertook the WCST under standard and modified (verbalization) administration. Subjects were stratified by the kind of WCST response (i.e. good, poor and remediable) and AP treatment (i.e. atypical vs. classical).

RESULTS

Subjects on atypical APs showed a better performance than those on classical ones. More poor performers who did not remediate were seen in the sample with classical Aps while subjects who remediated the performance were seen in the subgroup with atypical APs only. An increase of perseverative and total errors was seen in poor performers subjects on classical APs.

CONCLUSION

Subjects on atypicals showed a better cognitive pattern in terms of WCST performance. Since the naturalistic assignment of medication we cannot draw conclusions about its effect on cognitive performance and its interaction with cognitive remediation potential. However the data lead us to hypothesize that subjects with potential room for remediation did so with the atypical APs.

Executive function assessment of patients with schizophrenic disorder residual type in olanzapine treatment: an open study

Cognitive deficits are a fundamental feature of the schizophrenic disorder, but the effect of antipsychotic treatment is still debated. The study assesses the effect of olanzapine on neurocognitive functioning and symptomatology of patients with schizophrenic disorder residual type. Executive function evaluation by the Wisconsin card sorting test (WCST) was performed on 39 patients treated with olanzapine (5-20 mg/day); the efficacy of drug in improving symptomatology, safety and quality of life was also evaluated. After 7 months of treatment, the mean number of WCST categories tended to increase. Correct responses increased with a statistically significant change from the baseline. The total and unique errors decreased significantly. At all post-baseline visits a decrease from baseline in the PANSS total, positive and negative scores was seen. The proportion of patients with less severe illness (CGI), increased over the course of the study with a corresponding decrease of patients with more severe illness. The quality of life scores also tended to improve during treatment. The Simpson Angus scale, Barnes-akathisia and abnormal involuntary movement scale scores decreased consistently. The most common treatment emergent drug related adverse events were weight gain, insomnia, agitation and anxiety. Neurocognitive functioning in terms of executive performance and symptomatology improved in people with schizophrenia residual type.