Faculty Bibliography

Studies have shown that insulin resistance is associated with cognitive impairment. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists improve insulin sensitivity. The purpose of this study was to evaluate the effect of rosiglitazone, a PPAR-gamma agonist, on cognition in clozapine-treated patients with schizophrenia. In an eight-week double-blind, placebo-controlled pilot trial, clozapine-treated patients with schizophrenia were randomized to receive rosiglitazone (4mg/day) or placebo. A neuropsychological battery including the Digit Span subtest from the Wechsler Adult Intelligence Scale-III (WAIS-III), the verbal fluency test, the Hopkins Verbal Learning Test (HVLT), the Trail-Making Test (TMT) and the Wisconsin Card Sorting Test (WCST) was administered at baseline and week eight. Nineteen patients completed the study. There were no significant differences on any demographic or general clinical variables between the rosiglitazone group (n=9) and the placebo group (n=10). When baseline scores were controlled, there were no significant differences in change scores of cognitive performance over eight weeks between the two groups. In this pilot study, rosiglitazone had no cognitive benefit in clozapine-treated patients with schizophrenia. Future studies with longer treatment duration and larger sample size are needed to further explore the potential role of rosiglitazone in improving cognitive function in patients with schizophrenia.

OBJECTIVES: Varenicline was approved by the FDA in 2006. In 2009, based largely on case reports, the FDA issued a warning of possible adverse neuropsychiatric effects including depression and suicidal thoughts and behavior for varenicline and bupropion. Prospective trials of varenicline have not reported increased incidence of psychiatric adverse events other than sleep disturbance, but smokers with major mental illness have been excluded from large prospective trials of varenicline to date. We sought to evaluate the effect of a standard open-label 12-week varenicline trial on prospectively assessed safety and smoking outcomes in stable, treated adults with schizophrenia spectrum disorder and nicotine dependence. METHODS: One-hundred-and-twelve stable outpatients who smoked >10 cigarettes/day participated in a 12-week, open-label, smoking cessation trial of varenicline and weekly group cognitive behavioral therapy. Participants took varenicline for 4 weeks before attempting cessation. Trained raters collected safety and smoking outcome data weekly. RESULTS: Participants demonstrated improved psychotic symptoms, depressive symptoms and nicotine withdrawal symptoms from baseline to week 12 or early termination. At the end of 12 weeks open label treatment, the 14- and 28-day continuous abstinence rates were 47.3 and 34%, respectively. Expired CO declined significantly during treatment in those who did not achieve abstinence. CONCLUSIONS: This prospective study suggests that varenicline may be well-tolerated and effective for smoking cessation in combination with group CBT in stable outpatients with schizophrenia, a group with high rates of smoking and smoking-attributable morbidity and mortality.

CONTEXT Abnormalities in associative memory processes, such as Pavlovian fear conditioning and extinction, have been observed in schizophrenia. The retrieval of fear extinction memories (safety signals) may be particularly affected; although schizophrenic patients can extinguish conditioned fear, they show a deficit in retrieving fear extinction memories after a delay. The neurobiological basis of this abnormality is unknown, but clues have emerged from studies in rodents and humans demonstrating that the ventromedial prefrontal cortex (vmPFC) is a key mediator of extinction memory retrieval. OBJECTIVE To measure autonomic and neural responses during the acquisition and extinction of conditioned fear and the delayed recall of fear and extinction memories in patients with schizophrenia and healthy control participants. DESIGN Cross-sectional case control, functional magnetic resonance imaging study. SETTING Academic medical center. PARTICIPANTS Twenty schizophrenic patients and 17 healthy control participants demographically matched to the patient group. MAIN OUTCOME MEASURES Skin conductance and blood oxygen level-dependent responses. RESULTS During fear conditioning, schizophrenic patients showed blunted autonomic responses and abnormal blood oxygen level-dependent responses, relative to control participants, within the posterior cingulate gyrus, hippocampus, and other regions. Several of these abnormalities were linked to negative symptoms. During extinction learning, patients with schizophrenia and control participants showed comparable autonomic and neural responses. Twenty-four hours after the learning phases, the control subjects exhibited decreased fear and increased vmPFC responses in the extinction (safe) context as expected, indicating successful retention of the extinction memory. In contrast, the schizophrenic patients showed inappropriately elevated fear and poor vmPFC responses in the safe context. CONCLUSION Failure of extinction memory retrieval in schizophrenia is associated with vmPFC dysfunction. In future studies, abnormalities in fear learning and extinction recall may serve as quantitative phenotypes that can be linked to genetic, symptom, or outcome profiles in schizophrenia and those at risk for the disorder.

As a partial agonist at the glycine site of the NMDA receptor, D-cycloserine (DCS) has been viewed as lacking potency to fully test the NMDA receptor hypofunction theory of schizophrenia. However, findings of full agonist activity at a subset of NMDA receptors that may have particular relevance to schizophrenia, plus a growing body of evidence demonstrating enhancement of learning and neuroplasticity in animal models, suggest novel therapeutic strategies with DCS in schizophrenia. Preliminary studies with once-weekly administration have supported this potential new role for DCS in schizophrenia by demonstrating benefit for negative symptoms, memory consolidation, and facilitation of cognitive behavioral therapy for delusions.

BACKGROUND: Previous studies have suggested that motivational aspects of executive functioning, which may be disrupted in schizophrenia patients with negative symptoms, are mediated in part by the striatum. Negative symptoms have been linked to impaired recruitment of both the striatum and the dorsolateral prefrontal cortex (DLPFC). Here we tested the hypothesis that negative symptoms are associated primarily with striatal dysfunction, using functional magnetic resonance imaging (fMRI).MethodWorking-memory load-dependent activation and gray matter volumes of the striatum and DLPFC were measured using a region-of-interest (ROI) approach, in 147 schizophrenia patients and 160 healthy controls. In addition to testing for a linear relationships between striatal function and negative symptoms, we chose a second, categorical analytic strategy in which we compared three demographically and behaviorally matched subgroups: patients with a high burden of negative symptoms, patients with minimal negative symptoms, and healthy subjects. RESULTS: There were no differences in striatal response magnitudes between schizophrenia patients and healthy controls, but right DLPFC activity was higher in patients than in controls. Negative symptoms were inversely associated with striatal, but not DLPFC, activity. In addition, patients with a high burden of negative symptoms exhibited significantly lower bilateral striatal, but not DLPFC, activation than schizophrenia patients with minimal negative symptoms. Working memory performance, antipsychotic exposure and changes in gray matter volumes did not account for these differences. CONCLUSIONS: These data provide further evidence for a robust association between negative symptoms and diminished striatal activity. Future work will determine whether low striatal activity in schizophrenia patients could serve as a reliable biomarker for negative symptoms

BACKGROUND: Sleep spindles are thought to induce synaptic changes and thereby contribute to memory consolidation during sleep. Patients with schizophrenia show dramatic reductions of both spindles and sleep-dependent memory consolidation, which may be causally related. METHODS: To examine the relations of sleep spindle activity to sleep-dependent consolidation of motor procedural memory, 21 chronic, medicated schizophrenia outpatients and 17 healthy volunteers underwent polysomnography on two consecutive nights. On the second night, participants were trained on the finger-tapping motor sequence task (MST) at bedtime and tested the following morning. The number, density, frequency, duration, amplitude, spectral content, and coherence of stage 2 sleep spindles were compared between groups and examined in relation to overnight changes in MST performance. RESULTS: Patients failed to show overnight improvement on the MST and differed significantly from control participants who did improve. Patients also exhibited marked reductions in the density (reduced 38% relative to control participants), number (reduced 36%), and coherence (reduced 19%) of sleep spindles but showed no abnormalities in the morphology of individual spindles or of sleep architecture. In patients, reduced spindle number and density predicted less overnight improvement on the MST. In addition, reduced amplitude and sigma power of individual spindles correlated with greater severity of positive symptoms. CONCLUSIONS: The observed sleep spindle abnormalities implicate thalamocortical network dysfunction in schizophrenia. In addition, the findings suggest that abnormal spindle generation impairs sleep-dependent memory consolidation in schizophrenia, contributes to positive symptoms, and is a promising novel target for the treatment of cognitive deficits in schizophrenia

BACKGROUND: Cognitive dysfunction is a key predictor of functional disability in schizophrenia. Davunetide (AL-108, NAP) is an intranasally administered peptide currently being developed for treatment of Alzheimer's disease and related disorders. This study investigates effects of davunetide on cognition in schizophrenia. METHOD: Sixty-three subjects with schizophrenia received davunetide at one of two different doses (5, 30mg) or placebo for 12weeks in a multicenter, double-blind, parallel-group randomized clinical trial. The MATRICS Consensus Cognitive Battery (MCCB) assessed cognitive effects. The UCSD Performance-based Skills Assessment (UPSA) and the Schizophrenia Cognition Rating Scale (SCoRS) assessed functional capacity. Subjects continued their current antipsychotic treatment during the trial. RESULTS: There were no significant differences in MCCB change between davunetide and placebo over the three treatment arms (p=.45). Estimated effect-size (d) values were .34 and .21 favoring the 5 and 30mg doses vs. placebo, respectively. For UPSA, there was a significant main effect of treatment across study arms (p=.048). Between-group effect size (d) values were.74 and .48, favoring the 5 and 30mg doses, respectively. No significant effects were observed on the SCoRS or on symptom ratings. No significant side effects or adverse events were observed. CONCLUSION: Davunetide was well tolerated. Effects of davunetide on MCCB-rated cognition were not significant relative to placebo. In contrast, a significant beneficial effect was detected for the UPSA. Based upon effect-size considerations, sample sizes of at least 45-50 subjects/group would be required to obtain significant effects on both MCCB and UPSA, providing guidance for continued clinical development in schizophrenia