Stimulating the development of drug treatments to improve cognition in schizophrenia

Adolescent neurostimulation of dopamine circuit reverses genetic deficits in frontal cortex function

Dopamine system dysfunction is implicated in adolescent-onset neuropsychiatric disorders. Although psychosis symptoms can be alleviated by antipsychotics, cognitive symptoms remain unresponsive and novel paradigms investigating the circuit substrates underlying cognitive deficits are critically needed. The frontal cortex and its dopaminergic input from the midbrain are implicated in cognitive functions and undergo maturational changes during adolescence. Here, we used mice carrying mutations in Arc or Disc1 to model mesofrontal dopamine circuit deficiencies and test circuit-based neurostimulation strategies to restore cognitive functions. We found that in a memory-guided spatial navigation task, frontal cortical neurons were activated coordinately at the decision-making point in wild-type but not Arc-/- mice. Chemogenetic stimulation of midbrain dopamine neurons or optogenetic stimulation of frontal cortical dopamine axons in a limited adolescent period consistently reversed genetic defects in mesofrontal innervation, task-coordinated neuronal activity, and memory-guided decision-making at adulthood. Furthermore, adolescent stimulation of dopamine neurons also reversed the same cognitive deficits in Disc1+/- mice. Our findings reveal common mesofrontal circuit alterations underlying the cognitive deficits caused by two different genes and demonstrate the feasibility of adolescent neurostimulation to reverse these circuit and behavioral deficits. These results may suggest developmental windows and circuit targets for treating cognitive deficits in neurodevelopmental disorders.

Adolescent neurostimulation of dopamine circuit reverses genetic deficits in frontal cortex function

Dopamine system dysfunction is commonly implicated in adolescent-onset neuropsychiatric disorders. Although psychosis symptoms can be alleviated by antipsychotics, cognitive symptoms remain unresponsive to such pharmacological treatments and novel research paradigms investigating the circuit substrates underlying cognitive deficits are critically needed. The frontal cortex and its dopaminergic input from the midbrain are implicated in cognitive functions and undergo maturational changes during adolescence. Here, we used mice carrying mutations in the Arc or DISC1 genes to model mesofrontal dopamine circuit deficiencies and test circuit-based neurostimulation strategies to restore cognitive functions. We found that in a memory-guided spatial navigation task, frontal cortical neurons were activated coordinately at the decision-making point in wild-type but not Arc mutant mice. Chemogenetic stimulation of midbrain dopamine neurons or optogenetic stimulation of frontal cortical dopamine axons in a limited adolescent period consistently reversed genetic defects in mesofrontal innervation, task-coordinated neuronal activity, and memory-guided decision-making at adulthood. Furthermore, adolescent stimulation of dopamine neurons also reversed the same cognitive deficits in DISC1 mutant mice. Our findings reveal common mesofrontal circuit alterations underlying the cognitive deficits caused by two different genes and demonstrate the feasibility of adolescent neurostimulation to reverse these circuit and behavioral deficits. These results may suggest developmental windows and circuit targets for treating cognitive deficits in neurodevelopmental disorders.

The Impact of Sleep on Neurocognition and Functioning in Schizophrenia—Is It Time to Wake-Up?

People with schizophrenia (SZ) display substantial neurocognitive deficits that have been implicated as major contributors to poor daily functioning and disability. Previous reports have identified a number of predictors of poor neurocognition in SZ including demographics, symptoms, and treatment adherence, as well as body mass index, aerobic fitness, and exercise activity. However, the putative impact of sleep has received relatively limited consideration, despite sleep disturbances, which are pervasive in this population, resulting in symptoms that are strikingly similar to the neurocognitive deficits commonly observed in SZ. Here we argue for the consideration of the impact of sleep on neurocognition in people with SZ and propose recommendations for future research to elucidate the links between sleep parameters, neurocognition and daily functioning.

Online Social Cognition Training in Schizophrenia: A Double-Blind, Randomized, Controlled Multi-Site Clinical Trial

Social cognition (SC), the mental operations underlying social functioning, are impaired in schizophrenia. Their direct link to functional outcome and illness status have made them an important therapeutic target. However, no effective treatment for these deficits is currently applied as a standard of care. To address this need, we have developed SocialVille-an online, plasticity-based training program that targets SC deficits in schizophrenia. Here we report the outcomes of a double-blind, controlled, randomized, multi-site clinical trial of SocialVille. Outpatients with schizophrenia were randomized to complete 40 sessions of either SocialVille (N = 55 completers) or active control (computer games; N = 53 completers) from home. The a priori co-primary outcome measures were a social cognitive composite and a functional capacity outcome (UCSD Performance-based Skills Assessment [UPSA-2]). Secondary outcomes included a virtual functional capacity measure (VRFCAT), social functioning, quality of life, and motivation. Linear mixed models revealed a group × time interaction favoring the treatment group for the social cognitive composite (b = 2.81; P < .001) but not for the UPSA-2 measure. Analysis of secondary outcome measures showed significant group × time effects favoring the treatment group on SC and social functioning, on the virtual functional capacity measure and a motivation subscale, although these latter findings were nonsignificant with FDR correction. These results provide support for the efficacy of a remote, plasticity-based social cognitive training program in improving SC and social functioning in schizophrenia. Such treatments may serve as a cost-effective adjunct to existing psychosocial treatments. Trial Registration: NCT02246426.

Correlation between Performance-Based and Interview-Based Cognitive Measurements in Patients with Schizophrenia

OBJECTIVE

The Measurement and Treatment Research to improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB) is used to measure the cognitive function of patients with schizophrenia. In some situations, interview-based measures such as the Schizophrenia Cognition Rating Scale (SCoRS) may be appropriate. In this study, we analyzed the correlation between performance- and interview-based measurements in patients with schizophrenia.

METHODS

Fifty-six clinically stable patients were recruited. To evaluate cognitive function, we used the MCCB performance-based measure and the SCoRS interview-based measure. Measurements were taken at baseline, and 2 weeks and 3 months later. Spearman correlations were computed between each SCoRS item's interviewer rating and each MCCB score.

RESULTS

The correlation between the MCCB overall T score and the SCoRS global score was the strongest (r=-0.52), while the SCoRS total score and the MCCB Speed of Processing score also correlated (r=-0.48). The SCoRS global score showed statistically significant correlations with all seven MCCB domains and the overall T score.

CONCLUSION

This study reveals correlations between MCCB domains and SCoRS items. Since we find that interview-based measurements are highly correlated with performance-based measurements, we suggest them as a useful cognitive function evaluation tool that can easily be applied in clinical settings.

Dissociating self-reported cognitive complaint from clinical insight in schizophrenia

Whereas new pharmacological treatments are developed for cognitive impairments in schizophrenia, self-assessment of cognitive dysfunctioning besides their objective validity could be of interest in evaluating patients' motivation to engage in rehabilitation program. Nevertheless insight into symptoms is severely impaired in schizophrenia and is negatively linked with poor compliance. But it is yet unknown if patients with poor insight into their symptoms could have some insight into their cognitive impairments. The aim of this study was to explore the relationships existing between the cognitive complaint and the level of awareness of the disease in patients with schizophrenia. A total of 101 patients with DSM-IV schizophrenia or schizoaffective disorder and 60 control participants were recruited. Insight was assessed using the Scale to assess Unawareness of Mental Disorder (SUMD) and cognitive complaint intensity was assessed with the Scale to Investigate Cognition in Schizophrenia (SSTICS). Participants with schizophrenia displayed the same level of cognitive complaint when compared to healthy controls. Strong correlations were observed between SSTICS total score and duration of illness, levels of depression and state anxiety. Patients with a good insight into the therapeutic effects achieved with medication expressed a more important cognitive complaint. No correlations were found between the four others SUMD insight dimensions and total SSTICS score. The partial overlap of insight into illness and cognitive complaint suggests that insight is modular in schizophrenia. Assessment of cognitive complaint and awareness of illness need to be assessed before engagement in rehabilitation program.

Improving Cognition via Exercise (ICE): Study Protocol for a Multi-Site, Parallel-Group, Single-Blind, Randomized Clinical Trial Examining the Efficacy of Aerobic Exercise to Improve Neurocognition, Daily Functioning, and Biomarkers of Cognitive Change in Individuals with Schizophrenia

Individuals with schizophrenia (SZ) display cognitive deficits that have been identified as major determinants of poor functioning and disability, representing a serious public health concern and an important target for interventions. At present, available treatments offer only minimal to moderate benefits to ameliorate cognitive deficits. Thus, there remains an urgent need to identify novel interventions to improve cognition in people with SZ. Emerging evidence from animal and basic human research suggests aerobic exercise training (AE) has beneficial effects on cognition. Preliminary findings suggest that AE is efficacious in improving cognitive functioning in SZ, however the extant studies have been limited by small samples, a dearth of information on biologically-relevant covariates, and limited information on impact on daily functioning. Additionally, while AE-related cognitive benefits have been linked to Brain-Derived Neurotrophic Factor (BDNF) upregulation, this putative mechanism needs confirmation. The present report describes a study protocol designed to address these limitations-we review and summarize the current literature on treatment of cognitive deficits in SZ, state the rationale for employing AE to target these deficits, and describe the current protocol-a multi-site, single-blind, randomized clinical trial aiming to recruit 200 community-dwelling individuals with SZ. Participants are randomized to one of two 12-week interventions: AE using active-play video games (i.e., Xbox Kinect) and traditional cardiovascular exercise equipment or a stretching-and-toning (ST) control intervention. Participants undergo assessments of aerobic fitness, cognition, and daily functioning, as well as BDNF and other biomarkers of cognitive change, at baseline and after 6-and 12-weeks.

The effect of anticholinergic burden on cognitive and daily living functions in patients with schizophrenia

OBJECTIVE

This study aimed to explore the association between medication-associated anticholinergic burden and cognitive and daily living functions in patients with schizophrenia.

METHODS

Sixty patients with schizophrenia were recruited. We used the Anticholinergic Drug Scale (ADS) for evaluating medication-associated anticholinergic burden. The MATRICS Consensus Cognitive Battery (MCCB) and the University of California San Diego Performance-based Skills Assessment (UPSA) were used for evaluating cognitive and daily living functions. To assess clinical symptoms, psychiatrists conducted interviews using the Positive and Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia.

RESULTS

Subjects were divided into low (n = 31) and high (n = 29) anticholinergic burden based on ADS scores of 3 or more. The "high ADS" group had poorer cognitive (composite MCCB score, p < 0.001) and daily living functions (total UPSA score, p = 0.001) than the "low ADS" group. Medication-associated anticholinergic burden was negatively correlated with cognitive functions (composite MCCB score, r = -0.512, p < 0.001) and daily living functions (total UPSA score, r = -0.355, p = 0.005). A regression analysis showed that anticholinergic burden significantly explained the decline in cognitive functions (composite MCCB score, R² = 0.262, p < 0.001) and daily living functions (total UPSA score, R² = 0.126, p = 0.005). Explanatory power was reduced after a covariate adjustment, but the effects of the composite MCCB score (p = 0.013) and of the transportation domain score of the UPSA (p = 0.048) remained significant.

CONCLUSIONS

Our analysis shows that anticholinergic burden reduces cognitive and daily living functions in patients with schizophrenia. A drug strategy with minimal anticholinergic burden may be helpful to patients if it does not adversely affect clinical symptoms.

Neural changes following cognitive remediation therapy for schizophrenia

Patients with schizophrenia experience cognitive impairments that relate to poorer social functioning even after amelioration of positive symptoms. Pharmacological treatment and cognitive remediation are the two important therapeutic approaches for cognitive impairment in schizophrenia. Cognitive remediation therapy (CRT) for schizophrenia improves cognitive functioning and induces neuroplasticity, but different approaches and durations of CRT and different neuroimaging devices have led to varying results in meta-analyses. The objective of this review was to explore the impact of CRT on neurobiology. Several studies have provided evidence of increased activation in the frontal brain regions, such as the prefrontal cortex, anterior cingulate cortex, and parietal and occipital regions during working memory or executive function tasks after CRT. Two studies have shown alterations in resting-state connectivity between the prefrontal cortex and temporal regions. Two studies have reported that CRT induces changes in gray matter volume in the hippocampus. Further, one study observed that patients who had received CRT had elevated fractional anisotropy in the basal ganglia. We conclude that neuroimaging studies assessing CRT in patients with schizophrenia showed functional, structural, and connectivity changes that were positively correlated with cognitive improvements despite heterogeneous CRT approaches. Future studies that combine multiple modalities are required to address the differences, effects of intrinsic motivation, and pharmacological augmentation of CRT. Further understanding of the biological basis might lead to predictions of the CRT response in patients with schizophrenia and contribute to identification of schizophrenia patients for future interventions.

Adjunct transcranial direct current stimulation improves cognitive function in patients with schizophrenia: A double-blind 12-week study

OBJECTIVES

Cognitive impairment is a common symptom of schizophrenia that has significant effects on quality of life and the activities of daily living. The present study examined the ability of transcranial direct current stimulation (tDCS) to improve cognitive function and clinical symptoms in patients with schizophrenia.

METHODS

Fifty-six patients with schizophrenia were randomized to real-tDCS and sham-tDCS groups. The participants were stable for a period of 3months before study enrollment. Each group received 30min of active 2-mA tDCS or sham stimulation over the left dorsolateral prefrontal cortex (anode F3, cathode F4) once per day for 10 consecutive weekdays. The Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB) and Wisconsin Card Sorting Test (WCST) were used to evaluate cognitive function, and the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression-Schizophrenia scale (CGI-SCH), and Calgary Depression Scale for Schizophrenia (CDSS) were used to evaluate symptoms at baseline, after 10 sessions, and at 3-month follow-up.

RESULTS

There was a significant time×group interaction, indicating that MCCB working memory (P=0.008) and overall scores (P=0.031) improved over time in the real-tDCS group compared to the sham-tDCS group. There was also a significant time×group interaction for depressive symptoms as evaluated by the CGI-SCH, which decreased over time in the real-tDCS group (P=0.041). tDCS treatment combined with antipsychotic medication was generally well-tolerated and safe.

CONCLUSIONS

Adjunct tDCS treatment is safe and effective for improving cognitive status in patients with schizophrenia.

Olanzapine Reverses MK-801-Induced Cognitive Deficits and Region-Specific Alterations of NMDA Receptor Subunits

Cognitive dysfunction constitutes an essential component in schizophrenia for its early presence in the pathophysiology of the disease and close relatedness to life quality of patients. To develop effective treatment of cognitive deficits, it is important to understand their neurobiological causes and to identify potential therapeutic targets. In this study, adopting repeated MK-801 treatment as an animal model of schizophrenia, we investigated whether antipsychotic drugs, olanzapine and haloperidol, can reverse MK-801-induced cognitive deficits and how the reversal processes recruited proteins involved in glutamate neurotransmission in rat medial prefrontal cortex (mPFC) and hippocampus. We found that low-dose chronic MK-801 treatment impaired object-in-context recognition memory and reversal learning in the Morris water maze, leaving reference memory relatively unaffected, and that these cognitive deficits can be partially reversed by olanzapine, not haloperidol, treatment. At the molecular level, chronic MK-801 treatment resulted in the reduction of multiple N-methyl-D-aspartate (NMDA) receptor subunits in rat mPFC and olanzapine, not haloperidol, treatment restored the levels of GluN1 and phosphorylated GluN2B in this region. Taken together, MK-801-induced cognitive deficits may be associated with region-specific changes in NMDA receptor subunits and the reversal of specific NMDA receptor subunits may underlie the cognition-enhancing effects of olanzapine.

Early intervention in psychosis: clinical aspects of treatment

Engaging patients in first-episode psychosis services is critical in maximising the effect of early intervention and establishing a framework for longer-term treatment. Biopsychosocial assessments determine a working diagnosis and inform evidence-based treatment. Atypical antipsychotics should be used at doses that maximise therapeutic benefit and adherence while minimising side-effects. Patients are helped to construct a narrative of their illness, including a shared understanding of the contribution of biological and environmental risks, and early warning signs. Common comorbid conditions, including depression, suicidal ideation, substance misuse and anxiety, should be addressed. Management of comorbid borderline and antisocial personality disorders is difficult; their nexus with psychosis is discussed. Cognitive–behavioural therapy is a mainstay of treatment, with specific interventions developed for problems typical in first-episode presentations. Core psychosocial interventions include psychoeducation, vocational and educational support, family interventions and multimodal group programmes.

Correlation Between Brain Activation Changes and Cognitive Improvement Following Cognitive Remediation Therapy in Schizophrenia: An Activation Likelihood Estimation Meta-analysis

Background:

Several studies using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have indicated that cognitive remediation therapy (CRT) might improve cognitive function by changing brain activations in patients with schizophrenia. However, the results were not consistent in these changed brain areas in different studies. The present activation likelihood estimation (ALE) meta-analysis was conducted to investigate whether cognitive function change was accompanied by the brain activation changes, and where the main areas most related to these changes were in schizophrenia patients after CRT. Analyses of whole-brain studies and whole-brain + region of interest (ROI) studies were compared to explore the effect of the different methodologies on the results.

Methods:

A computerized systematic search was conducted to collect fMRI and PET studies on brain activation changes in schizophrenia patients from pre- to post-CRT. Nine studies using fMRI techniques were included in the meta-analysis. Ginger ALE 2.3.1 was used to perform meta-analysis across these imaging studies.

Results:

The main areas with increased brain activation were in frontal and parietal lobe, including left medial frontal gyrus, left inferior frontal gyrus, right middle frontal gyrus, right postcentral gyrus, and inferior parietal lobule in patients after CRT, yet no decreased brain activation was found. Although similar increased activation brain areas were identified in ALE with or without ROI studies, analysis including ROI studies had a higher ALE value.

Conclusions:

The current findings suggest that CRT might improve the cognition of schizophrenia patients by increasing activations of the frontal and parietal lobe. In addition, it might provide more evidence to confirm results by including ROI studies in ALE meta-analysis.

Family-Directed Cognitive Adaptation Pilot: Teaching Cognitive Adaptation to Families of Individuals with Schizophrenia

Cognitive deficits are a major determinant of functional outcome in schizophrenia. A promising treatment involves teaching individuals to use cognitive adaptation strategies to minimize the functional impact of cognitive difficulties. We developed Family Directed Cognitive Adaptation (FCA) to train caregivers to help their relatives with schizophrenia use cognitive adaptations to improve living skills. The goal of this open pilot trial was to examine the feasibility of FCA. Ten adults with schizophrenia, each with at least one relative, participated in FCA and were evaluated at baseline, post-treatment, and 6-month follow-up. Domains assessed included adaptive functioning, psychiatric symptoms, school/work involvement, hospitalizations, family burden, and treatment satisfaction. Participants reported high levels of satisfaction with FCA, and all families completed the 16-session intervention. Relatives reported reduced burden at termination and follow-up. No participants were hospitalized during the treatment or follow-up period, and rates of work/school involvement increased from 30% at baseline to 50% at the end of treatment and follow-up. Individuals improved in negative symptoms and adaptive functioning over the course of treatment, but these gains were not maintained. This pilot provides preliminary support for the acceptability and feasibility of FCA, and points to the need to address the maintenance of treatment gains after termination.

Randomized controlled trial of computer-based treatment of social cognition in schizophrenia: the TRuSST trial protocol

BACKGROUND

Schizophrenia is a severe and chronic medical condition, characterized by positive and negative symptoms, as well as pervasive social cognitive deficits. Despite the functional significance of the social cognition deficits affecting many aspects of daily living, such as social relationships, occupational status, and independent living, there is still no effective treatment option for these deficits, which is applied as standard of care. To address this need, we developed a novel, internet-based training program that targets social cognition deficits in schizophrenia (SocialVille). Preliminary studies demonstrate the feasibility and initial efficacy of Socialville in schizophrenia patients (Nahum et al., 2014). The purpose of the current trial (referred to as the TReatment of Social cognition in Schizophrenia Trial or TRuSST) is to compare SocialVille to an active control training condition, include a larger sample of patients, and assess both social cognitive functioning, and functional outcomes.

METHODS/DESIGN

We will employ a multi-site, longitudinal, blinded, randomized controlled trial (RCT) design with a target sample of 128 patients with schizophrenia. Patients will perform, at their home or in clinic, 40 sessions of either the SocialVille training program or an active control computer game condition. Each session will last for 40-45 minutes/day, performed 3-5 days a week, over 10-12 weeks, totaling to 30 hours of training. Patients will be assessed on a battery of social cognitive, social functioning and functional outcomes immediately before training, mid-way through training (after 20 training sessions) and at the completion of the 40 training sessions.

DISCUSSION

The strengths of this protocol are that it tests an innovative, internet-based treatment that targets fundamental social cognitive deficits in schizophrenia, employs a highly sensitive and extensive battery of functional outcome measures, and incorporates a large sample size in an RCT design.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02246426 Registered 16 September 2014.

Aerobic fitness and body mass index in individuals with schizophrenia: Implications for neurocognition and daily functioning

Previous reports indicate that among healthy individuals low aerobic fitness (AF) and high body-mass index (BMI) predict poor neurocognition and daily-functioning. It is unknown whether these associations extend to disorders characterized by poor neurocognition, such as schizophrenia. Therefore, we compared AF and BMI in individuals with schizophrenia and non-clinical controls, and then within the schizophrenia group we examined the links between AF, BMI, neurocognition and daily-functioning. Thirty-two individuals with schizophrenia and 64 gender- and age-matched controls completed assessments of AF (indexed by VO2max) and BMI. The former also completed measures of neurocognition, daily-functioning and physical activity. The schizophrenia group displayed significantly lower AF and higher BMI. In the schizophrenia group, AF was significantly correlated with overall neurocognition (r=0.57), along with executive functioning, working memory, social cognition, and processing speed. A hierarchical regression analysis indicated that AF accounted for 22% of the neurocognition variance. Furthermore, AF was significantly correlated with overall daily-functioning (r=0.46). In contrast, BMI displayed significant inverse correlations with neurocognition, but no associations to daily-functioning. AF was significantly correlated physical activity. The authors discuss the potential use of AF-enhancing interventions to improve neurocognitive and daily-functioning in schizophrenia, along with putative neurobiological mechanisms underlying these links, including Brain-Derived Neurotrophic Factor.

Effects of Add-on Ramelteon on Cognitive Impairment in Patients with Schizophrenia: An Open-label Pilot Trial

OBJECTIVE

This open-label study examined the effects of ramelteon on cognitive functions in 10 outpatients with schizophrenia.

METHODS

Ramelteon (8 mg/day) was administered to 10 patients with schizophrenia for six months. The verbal fluency test, Trail-Making Test, the Wisconsin Card Sorting Test, the Stroop Test, the Digit Span Distraction Test, Iowa Gambling Task, the Rey Auditory Verbal Learning Test were evaluated at baseline and 6 months after treatment with ramelteon.

RESULTS

Ramelteon improved significantly the scores of Rey Auditory Verbal Learning Test. Additionally, ramelteon exerted improvements in the verbal fluency and Iowa Gambling Task in 4 patients.

CONCLUSION

Ramelteon could be a potential therapeutic drug, in adjunctive treatment of learning and memory deficits seen in patients with schizophrenia.

Modulation of auditory deviance detection by acute nicotine is baseline and deviant dependent in healthy nonsmokers: a mismatch negativity study

OBJECTIVE

Cognitive enhancement resulting from nicotinic acetylcholine receptor stimulation may be evidenced by increased efficiency of the auditory-frontal cortex network of auditory discrimination, which is impaired in schizophrenia, a cognitive disorder associated with excessive tobacco use. Investigating automatic (preattentive) detection of acoustic change with the mismatch negativity (MMN) brain event-related potential in response to nicotine in individuals with varying baseline levels of auditory discrimination may provide useful insight into the cholinergic regulation of this neural network and its potential amelioration with novel nicotinic agents.

METHODS

Sixty healthy, non-smoking male volunteers were presented with an 'optimal' multi-feature MMN paradigm in a randomized, placebo controlled double-blind design with 6 mg of nicotine gum.

RESULTS

Participants with low, medium, and high baseline amplitudes responded differently to nicotine (vs. placebo), and nicotine response was feature specific. Whereas MMN in individuals with high amplitudes was diminished by nicotine, MMN increased in those with low amplitudes. Nicotine effects were not shown in medium amplitude participants.

CONCLUSIONS

These findings provide preliminary support for the role of nicotinic neurotransmission in sensory memory processing of auditory change and suggest that nicotinic receptor modulation can both enhance and diminish change detection, depending on baseline MMN and its eliciting stimulus feature.

Effects of antipsychotic drugs on insight in schizophrenia

Lack of insight is predominant in schizophrenia though the causes are still unclear. The present study was carried on to investigate the effect of three Second Generation Antipsychotics (SGAs) and Haloperidol on insight and the associations among different clusters of symptoms and insight. Fifty-five patients have been recruited at the moment of pharmacological switch needed for psychotic exacerbation, from other antipsychotic drugs to Olanzapine, Aripiprazole, Ziprasidone and Haloperidol. Patients have been followed for 6 months and evaluated at baseline, after 3 months and after 6 months. Regarding the insight improvement, all SGAs resulted more effective than Haloperidol, while no difference was detected among different SGAs. Concerning psychopathology, all SGAs showed a better efficacy than Haloperidol, positive symptoms apart. All SGAs showed a similar efficacy on all domains, except for negative symptoms which resulted less responsive to ziprasidone and haloperidol. An association between improvement of insight and psychopathology was detected. Furthermore, insight appears to be related to psychopathology severity, particularly to negative symptoms. However, the observed different effectiveness of Ziprasidone on negative symptoms and insight suggests that these psychopathological features may be not strictly related and, thus, they may be sustained by different psychopathological processes.

Brain plasticity-based therapeutics

The primary objective of this review article is to summarize how the neuroscience of brain plasticity, exploiting new findings in fundamental, integrative and cognitive neuroscience, is changing the therapeutic landscape for professional communities addressing brain-based disorders and disease. After considering the neurological bases of training-driven neuroplasticity, we shall describe how this neuroscience-guided perspective distinguishes this new approach from (a) the more-behavioral, traditional clinical strategies of professional therapy practitioners, and (b) an even more widely applied pharmaceutical treatment model for neurological and psychiatric treatment domains. With that background, we shall argue that neuroplasticity-based treatments will be an important part of future best-treatment practices in neurological and psychiatric medicine.

Drug approval and drug effectiveness

Data on the efficacy and safety of psychiatric medicines should form the foundation of evidence-based treatment practices. The US Food and Drug Administration (FDA) reviews such data in determining whether to approve new treatments, and the published literature serves as a repository for evidence on treatment benefits and harms. We describe the FDA review of clinical trials, examining the underlying logic and legal guidelines. Several FDA reviews provide evidence that the agency requires only minimal efficacy for psychiatric drugs. Further, in some instances, the FDA has relied on secondary rather than primary outcomes and has discounted the findings of negative studies in its review of antidepressant and antipsychotic medications. The published literature provides another lens into the safety and efficacy of treatments. We describe how treatment efficacy is systematically overstated and treatment-related harms are understated in the scientific literature. Suggestions are provided to improve public access to underlying safety and efficacy data and for the FDA to potentially improve its review process.

Age-dependent regulation of synaptic connections by dopamine D2 receptors

Dopamine D2 receptors (D2R) are G protein-coupled receptors that modulate synaptic transmission and are important for various brain functions, including learning and working memory. Abnormal D2R signaling has been implicated in psychiatric disorders such as schizophrenia. Here we report a new function of D2R in dendritic spine morphogenesis. Activation of D2R reduced spine number via GluN2B- and cAMP-dependent mechanisms in mice. Notably, this regulation occurred only during adolescence. During this period, D2R overactivation caused by mutations in the schizophrenia risk gene Dtnbp1 led to spine deficiency, dysconnectivity in the entorhinal-hippocampal circuit and impairment of spatial working memory. Notably, these defects could be ameliorated by D2R blockers administered during adolescence. Our findings suggest an age-dependent function of D2R in spine development, provide evidence that D2R dysfunction during adolescence impairs neuronal circuits and working memory, and indicate that adolescent interventions to prevent aberrant D2R activity protect against cognitive impairment.

The influence of combined cognitive plus social-cognitive training on amygdala response during face emotion recognition in schizophrenia

Both cognitive and social-cognitive deficits impact functional outcome in schizophrenia. Cognitive remediation studies indicate that targeted cognitive and/or social-cognitive training improves behavioral performance on trained skills. However, the neural effects of training in schizophrenia and their relation to behavioral gains are largely unknown. This study tested whether a 50-h intervention which included both cognitive and social-cognitive training would influence neural mechanisms that support social ccognition. Schizophrenia participants completed a computer-based intervention of either auditory-based cognitive training (AT) plus social-cognition training (SCT) (N=11) or non-specific computer games (CG) (N=11). Assessments included a functional magnetic resonance imaging (fMRI) task of facial emotion recognition, and behavioral measures of cognition, social cognition, and functional outcome. The fMRI results showed the predicted group-by-time interaction. Results were strongest for emotion recognition of happy, surprise and fear: relative to CG participants, AT+SCT participants showed a neural activity increase in bilateral amygdala, right putamen and right medial prefrontal cortex. Across all participants, pre-to-post intervention neural activity increase in these regions predicted behavioral improvement on an independent emotion perception measure (MSCEIT: Perceiving Emotions). Among AT+SCT participants alone, neural activity increase in right amygdala predicted behavioral improvement in emotion perception. The findings indicate that combined cognition and social-cognition training improves neural systems that support social-cognition skills.

Complex relationships of nicotinic receptor actions and cognitive functions

Nicotine has been shown in a variety of studies to improve cognitive function including learning, memory and attention. Nicotine both stimulates and desensitizes nicotinic receptors, thus acting both as an agonist and a net antagonist. The relative roles of these two actions for nicotine-induced cognitive improvement have not yet been fully determined. We and others have found that acute nicotinic antagonist treatment can improve learning and attention. Nicotine acts on a variety of nicotinic receptor subtypes. The relative role and interactions of neuronal nicotinic receptor subtypes for cognition also needs to be better characterized. Nicotine acts on nicotinic receptors in a wide variety of brain areas. The role of some of these areas such as the hippocampus has been relatively well studied but other areas like the thalamus, which has the densest nicotinic receptor concentration are still only partially characterized. In a series of studies we characterized nicotinic receptor actions, anatomic localization and circuit interactions, which are critical to nicotine effects on the cognitive functions of learning, memory and attention. The relative role of increases and decreases in nicotinic receptor activation by nicotine were determined in regionally specific studies of the hippocampus, the amygdala, the frontal cortex and the mediodorsal thalamic nucleus with local infusions of antagonists of nicotinic receptor subtypes (α7 and α4β2). The understanding of the functional neural bases of cognitive function is fundamental to the more effective development of nicotinic drugs for treating cognitive dysfunction.

Treating impaired cognition in schizophrenia: the case for combining cognitive-enhancing drugs with cognitive remediation

Cognitive impairment is a well-documented feature of schizophrenia and represents a major impediment to the functional recovery of patients. The therapeutic strategies to improve cognition in schizophrenia have either used medications (collectively referred to as 'cognitive-enhancing drugs' in this article) or non-pharmacological training approaches ('cognitive remediation'). Cognitive-enhancing drugs have not as yet been successful and cognitive remediation has shown modest success. Therefore, we may need to explore new therapeutic paradigms to improve cognition in schizophrenia. The optimal approach may require a combination of cognitive-enhancing drugs with cognitive remediation. We review the available data from animal and human studies that provide the conceptual basis, proof-of-concept and illustrations of success of such combination strategies in experimental and clinical paradigms in other conditions. We address the major design issues relevant to the choice of the cognitive-enhancing drugs and cognitive remediation, as well as the timing and the duration of the intervention as will be relevant for schizophrenia. Finally, we address the practical realities of the development and testing of such combined approaches in the real-world clinical situation and conclude that while scientifically attractive, there are several practical difficulties to be overcome for this approach to be clinically feasible.

The potential role of dopamine D₃ receptor neurotransmission in cognition

Currently available treatments have limited pro-cognitive effects for neuropsychiatric disorders, such as schizophrenia, Parkinson's disease and Alzheimer's disease. The primary objective of this work is to review the literature on the role of dopamine D₃ receptors in cognition, and propose dopamine D₃ receptor antagonists as possible cognitive enhancers for neuropsychiatric disorders. A literature search was performed to identify animal and human studies on D₃ receptors and cognition using PubMed, MEDLINE and EMBASE. The search terms included "dopamine D₃ receptor" and "cognition". The literature search identified 164 articles. The results revealed: (1) D₃ receptors are associated with cognitive functioning in both healthy individuals and those with neuropsychiatric disorders; (2) D₃ receptor blockade appears to enhance while D₃ receptor agonism seems to impair cognitive function, including memory, attention, learning, processing speed, social recognition and executive function independent of age; and (3) D₃ receptor antagonists may exert their pro-cognitive effect by enhancing the release of acetylcholine in the prefrontal cortex, disinhibiting the activity of dopamine neurons projecting to the nucleus accumbens or prefrontal cortex, or activating CREB signaling in the hippocampus. These findings suggest that D₃ receptor blockade may enhance cognitive performance in healthy individuals and treat cognitive dysfunction in individuals with a neuropsychiatric disorder. Clinical trials are needed to confirm these effects.

Neuropsychological functions and visual contrast sensitivity in schizophrenia: the potential impact of comorbid posttraumatic stress disorder (PTSD)

Previous studies have revealed a high prevalence of posttraumatic stress disorder (PTSD) in patients with other severe mental disorders, including schizophrenia. However, the neuropsychological and psychophysical correlates of comorbid PTSD are less exactly defined. The purpose of the present study was to assess immediate and delayed memory, attention, visuospatial skills, language, and basic visual information processing in patients with schizophrenia with or without PTSD. We recruited 125 patients with schizophrenia and 70 healthy controls matched for visual acuity, age, gender, education, and socioeconomic status. Twenty-one of patients with schizophrenia exhibited comorbid PTSD. We administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and visual contrast sensitivity tasks for low spatial/high temporal frequency (0.3 cycle/degree and 18 Hz) and high spatial/low temporal frequency (10 cycles/degree and 1Hz) sinusoidal gratings. All patients were clinically stable and received antipsychotic medications. Results revealed that relative to healthy controls, patients with schizophrenia exhibited significant and generalized neuropsychological dysfunctions and reduced visual contrast sensitivity, which was more pronounced at low spatial/high temporal frequency. When we compared schizophrenia patients with and without PTSD, we found that patients with comorbid PTSD displayed lower scores for RBANS attention, immediate and delayed memory, and visuospatial scores. Schizophrenia patients with or without PTSD displayed similar visual contrast sensitivity. In conclusion, comorbid PTSD in schizophrenia may be associated with worse neuropsychological functions, whereas it does not affect basic visual information processing.

Emotional memory modulation in schizophrenia: an overview

OBJECTIVE

In healthy controls, the emotional charge of stimuli influences how well stimuli are remembered. Although patients with schizophrenia (SCZ) have deficits in memory and in emotional processing, studies on emotional memory modulation (EMM) in SCZ report contradictory results. The aim of this review was to investigate whether methodological differences could explain these contradictory results.

METHOD

We reviewed the literature to investigate whether task differences could explain these differences. Due to the methodological differences, a meta-analysis was not possible.

RESULTS

Fourteen studies were identified that used a total of 22 tasks to study EMM in patients with SCZ. Two-thirds of the tasks showed no differences in EMM between patients with SCZ and healthy controls. Differences in EMM were found more often when long-term compared to short-term memory was measured, when memory instructions were implicit instead of explicit and when stronger emotional stimuli were used. An overall memory deficit or the mode of retrieval was not related to EMM.

CONCLUSION

Deficits in EMM in long-term compared to short-term memory point toward impaired emotional modulation of memory consolidation. Reduced EMM on implicit, but not explicit, tasks suggests a deficit in unconsciously using emotional content to modulate memory.

Emotion awareness and regulation in individuals with schizophrenia: Implications for social functioning

Successful social functioning requires adaptive forms of emotion awareness and regulation. However, despite well-documented deficits in social functioning in individuals with schizophrenia, little is known about emotion awareness and regulation in this population. Therefore, we compared emotion awareness and regulation in individuals with schizophrenia and healthy controls, and then, within the schizophrenia group, we examined their impact on social functioning. Forty-four individuals with schizophrenia and 20 healthy controls completed measures of emotion awareness, emotion regulation, and social functioning, in addition to control measures, including neurocognitive functioning. Compared to controls, individuals with schizophrenia displayed significant deficits describing and identifying their emotions and used significantly less reappraisal and more suppression to regulate their emotions. Among the schizophrenia group, better social functioning was associated with the ability to identify, and in particular to describe emotions, better emotion management, as well as greater use of reappraisal and less use of suppression. A hierarchical multiple regression analysis indicated that, after controlling for age and neurocognition, difficulties describing feelings accounted for 35% of the social functioning variance. The present study highlights the importance of emotion awareness and regulation in schizophrenia, pointing to their substantial influence on social functioning above and beyond the impact of neurocognitive functioning.

Nicotine, Auditory Sensory Memory, and sustained Attention in a Human Ketamine Model of Schizophrenia: Moderating Influence of a Hallucinatory Trait

BACKGROUND

The procognitive actions of the nicotinic acetylcholine receptor (nAChR) agonist nicotine are believed, in part, to motivate the excessive cigarette smoking in schizophrenia, a disorder associated with deficits in multiple cognitive domains, including low-level auditory sensory processes and higher-order attention-dependent operations.

OBJECTIVES

As N-methyl-d-aspartate receptor (NMDAR) hypofunction has been shown to contribute to these cognitive impairments, the primary aims of this healthy volunteer study were to: (a) to shed light on the separate and interactive roles of nAChR and NMDAR systems in the modulation of auditory sensory memory (and sustained attention), as indexed by the auditory event-related brain potential - mismatch negativity (MMN), and (b) to examine how these effects are moderated by a predisposition to auditory hallucinations/delusions (HD).

METHODS

In a randomized, double-blind, placebo-controlled design involving a low intravenous dose of ketamine (0.04 mg/kg) and a 4 mg dose of nicotine gum, MMN, and performance on a rapid visual information processing (RVIP) task of sustained attention were examined in 24 healthy controls psychometrically stratified as being lower (L-HD, n = 12) or higher (H-HD) for HD propensity.

RESULTS

Ketamine significantly slowed MMN, and reduced MMN in H-HD, with amplitude attenuation being blocked by the co-administration of nicotine. Nicotine significantly enhanced response speed [reaction time (RT)] and accuracy (increased % hits and d' and reduced false alarms) on the RVIP, with improved performance accuracy being prevented when nicotine was administered with ketamine. Both % hits and d', as well as RT were poorer in H-HD (vs. L-HD) and while hit rate and d' was increased by nicotine in H-HD, RT was slowed by ketamine in L-HD.

CONCLUSIONS

Nicotine alleviated ketamine-induced sensory memory impairment and improved attention, particularly in individuals prone to HD.

Neural activity during emotion recognition after combined cognitive plus social cognitive training in schizophrenia

Cognitive remediation training has been shown to improve both cognitive and social cognitive deficits in people with schizophrenia, but the mechanisms that support this behavioral improvement are largely unknown. One hypothesis is that intensive behavioral training in cognition and/or social cognition restores the underlying neural mechanisms that support targeted skills. However, there is little research on the neural effects of cognitive remediation training. This study investigated whether a 50 h (10-week) remediation intervention which included both cognitive and social cognitive training would influence neural function in regions that support social cognition. Twenty-two stable, outpatient schizophrenia participants were randomized to a treatment condition consisting of auditory-based cognitive training (AT) [Brain Fitness Program/auditory module ~60 min/day] plus social cognition training (SCT) which was focused on emotion recognition [~5-15 min per day] or a placebo condition of non-specific computer games (CG) for an equal amount of time. Pre and post intervention assessments included an fMRI task of positive and negative facial emotion recognition, and standard behavioral assessments of cognition, emotion processing, and functional outcome. There were no significant intervention-related improvements in general cognition or functional outcome. fMRI results showed the predicted group-by-time interaction. Specifically, in comparison to CG, AT+SCT participants had a greater pre-to-post intervention increase in postcentral gyrus activity during emotion recognition of both positive and negative emotions. Furthermore, among all participants, the increase in postcentral gyrus activity predicted behavioral improvement on a standardized test of emotion processing (MSCEIT: Perceiving Emotions). Results indicate that combined cognition and social cognition training impacts neural mechanisms that support social cognition skills.

Clinical neuropsychology within adolescent and young-adult psychiatry: conceptualizing theory and practice

Historically, clinical neuropsychology has made significant contributions to the understanding of brain-behavior relationships, particularly in neurological conditions. During the past several decades, neuropsychology has also become established as an important discipline in psychiatric settings. Cognition is increasingly recognized as being core to psychiatric illnesses and predictive of functional outcomes, augmenting theories regarding symptomatology and illness progression. Adult-type psychiatric disorders (including schizophrenia and other psychotic, mood, anxiety, eating, substance-related, and personality disorders) typically emerge during adolescence or young adulthood, a critical neurodevelopmental period. Clinical neuropsychological assessment in adolescent psychiatric patients is particularly valuable in informing clinical formulation and intervention and can be therapeutic across a number of levels. This article articulates the theoretical considerations and practical challenges and applications of clinical neuropsychology within adolescent and young-adult psychiatry. The importance of considering the neurodevelopmental context and its relationship to current theoretical models underpinning clinical practice are discussed.

General and domain-specific neurocognitive impairments in deficit and non-deficit schizophrenia

Earlier studies suggested more severe overall cognitive impairments in deficit versus non-deficit schizophrenia; however, the specific contribution of different cognitive domains to this overall cognitive impairment remains unclear. The purpose of this study was to compare the two subtypes in general cognitive functioning as well as in individual cognitive domains using the composite score approach. One hundred and forty-three patients fulfilling the criteria for the deficit syndrome were compared with 123 patients diagnosed with non-deficit schizophrenia. Neurocognitive functioning was assessed by a neuropsychological test battery measuring the domains of sustained vigilance/attention, working memory, short-term memory, verbal memory, cognitive flexibility, and ideation fluency. Using the raw neuropsychological measures, we calculated a global index of cognitive impairment and domain-specific composite z-scores. Association between these composite scores and the deficit syndrome was examined by logistic regression analysis. After adjusting for relevant covariates including sex, age, education, smoking, and antipsychotic dose, results indicated a significant increase in the likelihood of deficit syndrome as a function of global (OR = 5.40; 95% CI 3.02-9.65) as well as domain-specific impairments (OR > 2 for all individual domains except for short-term memory). Cognitive flexibility was an independent predictor (OR = 2.92; 95% CI 1.47-5.80), whereas other cognitive domains demonstrated no unique contribution to the general cognitive impairment. Patients with deficit schizophrenia suffer from a more severe degree of neurocognitive impairment, which is qualitatively similar to the dysfunction seen in non-deficit schizophrenia. However, our results indicate that cognitive flexibility is specifically impaired in deficit versus non-deficit patients and may therefore represent a core feature of this subtype.

Different duration of at-risk mental state associated with neurofunctional abnormalities. A multimodal imaging study

OBJECTIVES

Neurofunctional alterations are correlates of vulnerability to psychosis, as well as of the disorder itself. How these abnormalities relate to different probabilities for later transition to psychosis is unclear. We investigated vulnerability- versus disease-related versus resilience biomarkers of psychosis during working memory (WM) processing in individuals with an at-risk mental state (ARMS).

EXPERIMENTAL DESIGN

Patients with "first-episode psychosis" (FEP, n = 21), short-term ARMS (ARMS-ST, n = 17), long-term ARMS (ARMS-LT, n = 16), and healthy controls (HC, n = 20) were investigated with an n-back WM task. We examined functional magnetic resonance imaging (fMRI) and structural magnetic resonance imaging (sMRI) data in conjunction using biological parametric mapping (BPM) toolbox.

PRINCIPAL OBSERVATIONS

There were no differences in accuracy, but the FEP and the ARMS-ST group had longer reaction times compared with the HC and the ARMS-LT group. With the 2-back > 0-back contrast, we found reduced functional activation in ARMS-ST and FEP compared with the HC group in parietal and middle frontal regions. Relative to ARMS-LT individuals, FEP patients showed decreased activation in the bilateral inferior frontal gyrus and insula, and in the left prefrontal cortex. Compared with the ARMS-LT, the ARMS-ST subjects showed reduced activation in the right inferior frontal gyrus and insula. Reduced insular and prefrontal activation was associated with gray matter volume reduction in the same area in the ARMS-LT group.

CONCLUSIONS

These findings suggest that vulnerability to psychosis was associated with neurofunctional alterations in fronto-temporo-parietal networks in a WM task. Neurofunctional differences within the ARMS were related to different duration of the prodromal state and resilience factors.

Top-down or bottom-up: Contrasting perspectives on psychiatric diagnoses

Clinical psychiatry is confronted with the expanding knowledge of medical genetics. Most of the research into the genetic underpinnings of major mental disorders as described in the categorical taxonomies, however, did reveal linkage with a variety of chromosomes. This heterogeneity of results is most probably due to the assumption that the nosological categories as used in these studies are disease entities with clear boundaries. If the reverse way of looking, the so-called bottom-up approach, is applied, it becomes clear that genetic abnormalities are in most cases not associated with a single psychiatric disorder but with a certain probability to develop a variety of aspecific psychiatric symptoms. The adequacy of the categorical taxonomy, the so-called top-down approach, seems to be inversely related to the amount of empirical etiological data. This is illustrated by four rather prevalent genetic syndromes, fragile X syndrome, Prader-Willi syndrome, 22q11 deletion syndrome, and Noonan syndrome, as well as by some cases with rare chromosomal abnormalities. From these examples, it becomes clear that psychotic symptoms as well as mood, anxiety, and autistic features can be found in a great variety of different genetic syndromes. A psychiatric phenotype exists, but comprises, apart from the chance to present several psychiatric symptoms, all elements from developmental, neurocognitive, and physical characteristics.

Cognition at illness onset as a predictor of later functional outcome in early psychosis: systematic review and methodological critique

BACKGROUND

Cognitive deficits occur early in the course of psychosis, are mostly stable, and have been identified as potential functional prognostic markers. Previous reviews of chronic schizophrenia have concluded that specific cognitive deficits are strongly associated with poorer functional outcomes. However, results of schizophrenia studies may be influenced by the effects of long-term illness or treatment or be biased toward individuals with poorer outcomes and may not be relevant to early psychosis (EP). This review aimed to systematically examine the evidence regarding general and social cognitive predictors of later functional outcome in EP and critique the methodology of the studies reviewed. A final aim was to conduct a meta-analysis of the studies reviewed, but methodological reasons precluded this.

METHOD

A comprehensive search of PsycINFO and MEDLINE databases identified 15 relevant articles and 7 further articles following a reference list search, totaling 22 included articles.

RESULTS

Most studies found at least one cognitive domain predicted functional outcome, but examination of separate cognitive domains revealed there were more null than significant associations between cognition and functional outcome across every cognitive domain. No study examined social cognition as a predictor of outcome. The frequency with which different cognitive domains predicted outcome varied depending on study methodology and this was most noticeable when studies with short-term follow-up were compared with longer-term follow-up studies.

CONCLUSIONS

Due to the methodological variability and limitations of the studies reviewed, firm conclusions regarding the relationship between cognition and functional outcomes in EP cannot be made. Tentatively, cognition may be prognostic in EP, especially for longer-term outcomes. However, further research that addresses the methodological issues identified, including examination of social cognition and other non-cognitive predictors, is needed.

Persisting cognitive deficits induced by low-dose, subchronic treatment with MK-801 in adolescent rats

Cognitive impairments have been proposed as a core feature of schizophrenia. Studies have shown that chronic or subchronic treatment with N-methyl-d-aspartate (NMDA) antagonists could induce cognitive deficits that resemble the symptoms of schizophrenia, yet few studies have investigated the effects of repeated NMDA blockade during adolescence on cognition. In the current study, adolescent, male rats were treated with an intraperitoneal injection of MK-801 (0.05, 0.1, and 0.2mg/kg) once daily for 14days. They were then tested 24h and 14days after drug cessation, respectively, in a series of behavioural tasks, including the object recognition task, the object-in-context recognition task and the working memory task of the Morris water maze (MWM). Results showed that object-in-context recognition and spatial working memory in the MWM were significantly impaired by repeated MK-801 treatment when animals were tested 24h after drug cessation, but object recognition was left intact. In particular, such deficits were observed 14days after drug cessation in the 0.2mg/kg group. The cognition-impairing effect of MK-801 could not be attributed to malnutrition or alterations in motor functions. Taken together, this study may provide support for establishing an animal model of cognitive deficits of schizophrenia based on low-dose, repeated treatment of MK-801 during adolescence.

Executive function in deficit schizophrenia: what do the dimensions of the Wisconsin Card Sorting Test tell us?

Neuropsychological characterization of the schizophrenia deficit syndrome is an unresolved issue. The initial assumption was that patients with deficit syndrome show more definitive impairments on tests sensitive for frontal and parietal functions compared with nondeficit patients,but recent studies failed to confirm this assumption. The fundamental question is whether a more refined delineation of executive dysfunctions is able to yield differences between deficit and nondeficit patients. To investigate this question, we implemented a factor analytic approach to explore potential differences between deficit and nondeficit patients using the Wisconsin Card Sorting Test (WCST). Our paper presents an exploratory factor analysis of the WCST on schizophrenia patients and healthy samples, and a comparison among deficit, non-deficit patients with schizophrenia and control samples using the identified factors. A total of 154 patients with schizophrenia fulfilling the criteria for the deficit syndrome, 121 nondeficit patients, and 130 healthy controls were compared. Factor analysis of the WCST variables using the principal component method resulted in a two-factor solution. Comparison of the diagnostic groups on each of the factors revealed that deficit schizophrenia patients suffer from a more severe degree of impairment on the 'General executive function' factor than nondeficit schizophrenia patients. To our knowledge this is the first study that compared patients with the deficit and non-deficit forms of schizophrenia using WCST factor analytic techniques. Our results provide an insight into the cognitive profile of schizophrenia patients with regard to WCST, which could serve as a framework for future clinical and research endeavors.

Symptomatic and functional correlates of regional brain physiology during working memory processing in patients with recent onset schizophrenia

Patients with schizophrenia show altered patterns of functional activation during working memory processing; specifically, high-performing patients appear to hyper-activate and low-performing patients appear to hypo-activate when compared with controls. It remains unclear how these individual differences in neurophysiological activation relate to the clinical presentation of the syndrome. In this functional magnetic resonance imaging (fMRI) study, the relationship is examined using partial least squares (PLS), a multivariate statistical technique that selects underlying latent variables based on the covariance between two sets of variables, in this case, clinical variables and regional fMRI activations during a verbal working memory task. The PLS analysis extracted two latent variables, and the significance of these associations was confirmed through permutation. Lower levels of activation during task performance across frontal and parietal regions of interest in the left hemisphere were found to covary with poorer role functioning and greater severity of negative and disorganized symptoms, while lower activation in right frontal and subcortical regions of interest was found to covary with better social functioning and fewer positive symptoms. These results suggest that appropriately lateralized patterns of functional activation during working memory processing are related to the severity of negative and disorganized symptoms and to the level of role and social functioning in schizophrenia.

Cognitive effects of second-generation antipsychotics: current insights into neurochemical mechanisms

Historically, pharmacotherapy for schizophrenia was mainly focused on finding drugs to treat psychotic symptoms only, without addressing other crucial domains of the disorder such as cognitive impairments. As a result, these domains have remained undertreated. In this review, we discuss recent preclinical research efforts, including investigation of synaptic mechanisms as well as intracellular signalling pathways and mechanisms involved in neuroplasticity and cell resilience, that may represent new mechanisms participating in the pathogenesis of schizophrenia, particularly at the level of the prefrontal cortex and hippocampus, and that might lead to the development of drugs that can counteract, at least partially, the cognitive impairments typical of schizophrenia.