Improvement of prefrontal brain function in endogenous psychoses under atypical antipsychotic treatment

Electrophysiological underpinnings of dysfunctional inhibitory control in adults with attention-deficit/hyperactivity disorder: evidence for reduced NoGo anteriorization

Our aim was to delineate the electrophysiological basis of dysfunctional inhibitory control of adult ADHD via investigating the anteriorization of the P3 component of the event-related brain response associated with the NoGo task condition (i.e., NoGo anteriorization, NGA). NGA is a neurophysiological measure of brain topography for cognitive response control, which indexes an overall shift of the brain's electrical activity in anterior direction towards the prefrontal areas. While the NoGo P3 received considerable attention in the adult ADHD literature, the brain topography of this component, which reflects the inhibitory process, remains largely unaddressed. EEG recordings were obtained during a Go/NoGo task from 51 subjects (n = 26 adult patients with ADHD, n = 25 healthy controls) using a high-density, 128-channel BioSemi ActiveTwo recording system. ADHD patients had significantly lower P3 NGA response compared to controls. The decrease in NGA was related to impulsivity scores as measured by the Conners' Adult ADHD Rating Scale: patients with higher impulsivity scores had significantly lower NGA. Treatment with stimulant medication, as compared to the lack of such treatment, was associated with a correction of the lower NGA response in ADHD patients. The current study revealed a lower NGA in adult ADHD, a finding which is consistent with the inhibitory control and frontal lobe dysfunctions described in the disorder. Our finding of the inverse relationship between NGA and impulsivity suggests that clinically more severe impulsivity is linked to a more pronounced frontal dysfunction in adult ADHD subjects.

L, Segura-Garcia C, De Fazio P. Effectiveness of SGA-LAIs on Clinical, Cognitive, and Social Domains in Schizophrenia: Results from a Prospective Naturalistic Study

We hypothesized that shifting from oral second-generation antipsychotics (SGA) to their long-acting injectable (LAI) counterpart would be beneficial for the psychopathological, cognitive, social, and general health domains in outpatients suffering from schizophrenia. We aimed to evaluate the prospective usefulness of SGA-LAI treatment by carrying out a head-to-head comparison of two different medications (i.e., aripiprazole monohydrate (Ari-LAI) and paliperidone palmitate 1 and 3 month (PP1M, PP3M)) in a real-world setting, assessing the effectiveness and tolerability of Ari-LAI and PP1M/PP3M over a 15 month follow-up. A total of 69 consecutive individuals affected by schizophrenia were screened for eligibility. Finally, 46 outpatients (29 treated with Ari-LAI, 13 with PP1M, and four with PP3M) were evaluated through clinical, functional, and neuropsychological assessment administrated at baseline and after 3-, 12-, and 15-month follow-up periods. Moreover, periodic general medical evaluations were carried out. We estimated an overall improvement over time on the explored outcomes, without differences with respect to the type of LAI investigated, and with a global 16.4% dropout rate. Our findings suggest that switching from oral SGA to SGA-LAIs represents a valid and effective treatment strategy, with significant improvements on psychopathological, cognitive, social, and clinical variables for patients suffering from schizophrenia, regardless of the type of molecule chosen.

[Positive changes in the severity of residual psychotic symptoms in schizophrenic patients switched to treatment with risperidone]

AIM

To evaluate the effect of changing therapy from typical antipsychotics to the atypical antipsychotic risperidone in the treatment of difficult-to-treat residual psychotic symptoms.

MATERIAL AND METHODS

The study included 15 patients, 8 men and 7 women, mean age 49.1±10.25 years, diagnosed with paranoid schizophrenia, partial remission (ICD-10 F20.04). At the beginning all participants received regular maintenance antipsychotic therapy with typical antipsychotics. The patient assessment with the PANSS, CGI scale and GAF scale was performed at the beginning (before the change of antipsychotics to risperidone) and in the end of the study. The primary efficacy endpoint was a reduction in scores on the PANSS items P1 'delusions' and P3 'hallucinatory behavior' to 1 (no such symptom) or 2 (minimal residual symptom). Secondary criteria were positive changes in the severity of other psychopathological symptoms and an increase in the social functioning level. The average dose of risperidone was 4.62±1.35 mg. The duration of treatment was 2 month.

RESULTS

After switching from typical antipsychotics to risperidone and two months monotherapy, there were significant positive changes in the total PANSS score as well as in positive subscale score and CGI-S score. The small, but statistically significant, changes were detected in the overall functioning of the patients (the increase in the GAF score). The dynamics of residual psychotic symptoms was unequal: the severity of hallucinatory symptoms decreased significantly while the delusional symptoms remained unchanged.

CONCLUSION

The authors suggest that excessive dopaminergic blockade might play a significant role in the pathogenesis of residual symptoms. This fact may explain the positive effect of treatment in the cases with the less degree of dopaminergic blockade. If it is true, the treatment strategy in the maintenance phase should not be a direct continuation of acute phase therapy and switching to other drugs and changing of the dose are needed.

The course of cognitive functioning after first-episode of psychosis: A six month follow-up study

Our aim with the present study was to evaluate rank-order and mean-level cognitive functioning stability among first-episode psychosis (FEP) patients, measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB), over a six month period. We also aimed to examine longitudinal measurement invariance and identify factors-such as age, gender, educational level, treatment and psychopathological change scores-potentially linked to cognitive change among patients. In addition, correlations between objectively measured and subjectively evaluated cognitive functioning were estimated. Neuropsychological assessments were administered to 85 patients after the initial stabilisation of their psychosis; 82 of the patients were retested. Subjectively perceived cognitive functioning was measured using a subscale derived from the Estonian version of the Subjective Well-Being Under Neuroleptic Scale (SWN-K-E). On average, executive functioning and processing speed improved significantly, while memory test scores decreased significantly, over time. Very high rank-order stability (r=0.80 to 0.94, p<0.001) was observed with all measured ability scores. Confirmatory factor analysis revealed the loadings of a single (broad ability) factor model were equal across both measurement occasions, but the lack of intercept invariance suggested that mean-level comparisons are more appropriately carried out at a subtest level. On average psychopathology scores and antipsychotics doses declined over time, with the latter also significantly correlating with better executive functioning. Gender was a significant moderator of some domains of cognitive performance, and decline tended to be somewhat more pronounced for women. The results also indicated the lack of any relationship between objective and subjective measurements of cognitive functioning.

Factors affecting cognitive remediation response in schizophrenia: the role of COMT gene and antipsychotic treatment

Cognitive remediation is the best available tool to treat cognitive deficits in schizophrenia and has evidence of biological validity; however results are still heterogeneous and significant predictors are lacking. Previous studies showed that cognitive remediation is able to induce changes in PFC function and dopaminergic transmission and thus the study of possible sources of variability at these levels (i.e. antipsychotic treatments and genetic variability) might help to gain a deeper understanding of neurobiological correlates and translate into optimization and personalization of interventions. In the present study, we analyzed the interaction between pharmacological treatment (clozapine vs typical/atypical D2 blockers) and COMT rs4680 polymorphism on cognitive changes after cognitive remediation therapy, in a sample of 98 clinically stabilized patients with schizophrenia. The General Linear Model showed a significant interaction of pharmacological treatment and COMT polymorphism on the improvement in "Symbol Coding" subtest, a global measure of speed of processing. Post-hoc analysis revealed a significant difference between COMT genotypes, when treated with D2 blockers, with worse results among Val/Val patients. These preliminary results suggest that genetic variability, influencing prefrontal dopamine, might affect individual capacity to improve with different patterns, depending on antipsychotic treatment.

Hypofrontality in schizophrenic patients and its relevance for the choice of antipsychotic medication: an event-related potential study

OBJECTIVES

One of the neurobiological core features of schizophrenic illnesses is a hypo-functionality of the frontal cortex ("cerebral hypofrontality"). The two major classes of antipsychotic medication differ regarding their impact on frontal lobe function and metabolism, with a presumably more positive effect of "atypical" compared to "typical" agents. To date, neurobiological markers reliably predicting the treatment response to different antipsychotics are lacking. The present study, therefore, aimed at establishing a neurophysiological marker of frontal lobe function (NoGo-Anteriorization, NGA) as a predictor of the treatment response to first- and second-generation antipsychotics.

METHODS

Seventy-six schizophrenic patients were examined three times over a 6-week study period. Patients were treated with first- or second-generation antipsychotics, and NGA, neurocognitive performance, and symptomatology were assessed on admission as well as during two follow-up measurements.

RESULTS

Baseline NGA values significantly predicted the treatment response to typical and atypical antipsychotics; however, the direction of this prediction was dependent on the antipsychotic drug regimen. Moreover, atypical antipsychotics had a superior impact on neurocognitive performance and self-reported quality of life.

CONCLUSIONS

The NGA might be a useful tool in developing individualized treatment strategies based on pathophysiological aspects of schizophrenic illnesses that can be easily determined in clinical routine settings.

DTNBP1 (dysbindin) gene variants modulate prefrontal brain function in schizophrenic patients--support for the glutamate hypothesis of schizophrenias

Dysbindin (DTNBP1) is a recently characterized protein that seems to be involved in the modulation of glutamatergic neurotransmission in the human brain, thereby influencing prefrontal cortex function and associated cognitive processes. While association, neuroanatomical and cellular studies indicate that DTNBP1 might be one of several susceptibility genes for schizophrenia, the effect of dysbindin on prefrontal brain function at an underlying neurophysiological level has not yet been explored for these patients. The NoGo-anteriorization (NGA) is a topographical event-related potential measure, which has been established as a valid neurophysiological marker of prefrontal brain function. In the present study, we investigated the influence of seven dysbindin gene variants on the NGA in a group of 44 schizophrenic patients. In line with our a priori hypothesis, one DTNBP1 polymorphism previously linked to schizophrenia (rs2619528) was found to be associated with changes in the NGA; however, the direction of this association directly contrasts with our previous findings in a healthy control sample. This differential impact of DTNBP1 gene variation on prefrontal functioning in schizophrenic patients vs. healthy controls is discussed in terms of abnormal glutamatergic baseline levels in patients suffering from schizophrenic illnesses. This is the first report on a role of DTNBP1 gene variation for prefrontal functioning at a basic neurophysiological level in schizophrenic patients. An impact on fundamental processes of cognitive response control may be one mechanism by which DTNBP1 gene variants via glutamatergic transmission contribute to the pathophysiology underlying schizophrenic illnesses.

Detection of the moderately beneficial cognitive effects of low-dose treatment with haloperidol or clozapine in an animal model of the attentional impairments of schizophrenia

The absence of effective cognition enhancers for the treatment of patients with schizophrenia limits the validation of animal models and behavioral tests used for drug finding and characterization. However, low doses of haloperidol and clozapine were documented to produce moderately beneficial effects in patients. Therefore, this experiment was designed to determine the attentional effects of such treatments in a repeated-amphetamine (AMPH) animal model. Animals were trained in an operant-sustained attention task and underwent a 40-day pretreatment period with saline or increasing doses (1-10 mg per kg) of AMPH. After regaining baseline performance following 10 days of saline treatment, animals were treated with haloperidol (0.025 mg per kg), clozapine (2.5 mg per kg), or vehicle for 10 days. Furthermore, the effects of AMPH challenges (1.0 mg per kg) were assessed. In AMPH-pretreated animals, the administration of AMPH challenges resulted in the disruption of attentional performance. Treatment with haloperidol and clozapine attenuated the detrimental performance effects of these challenges, with clozapine exhibiting more robust attenuation. Furthermore, clozapine, but not haloperidol, impaired the performance of control animals. In contrast, the performance of AMPH-pretreated animals remained unaffected by clozapine. As this animal model detects the moderately beneficial cognitive effects of haloperidol and clozapine, it may be useful for preclinical research designed to detect and characterize treatments for the cognitive symptoms of schizophrenia.

Dysfunction of the Left Dorsolateral Prefrontal Cortex is Primarily Responsible for Impaired Attentional Processing in Schizophrenia

OBJECTIVE

The results for finding the deficit in the anterior cingulate (ACC) in schizophrenic patients (SZ) have been inconsistent according to the studies that used different Stroop tasks, which is unlike the deficit in the dorsolateral prefrontal cortex (DLPFC). In order to explore for the core region that's responsible for the selective attention deficit in SZ, we examined the results of a functional neuroimaging study, which involved the performance of the Stroop task using high or low prefrontal cortex related loads in SZ.

METHODS

Ten schizophrenic patients and healthy controls (HC) received functional magnetic resonance imaging (fMRI) during a Short/Long-term latency Stroop task. The changes in the neural activity were determined in well-known Stroop related regions of interest (ROIs) that consisted of the DLPFC, ACC, the parietal lobule and in the whole brain regions for both the main and interaction effects of latency, and the results of the short-term and long-term latency Stroop conditions were compared.

RESULTS

The response times for both the congruency and latency effects were more prolonged in the schizophrenics than in the HC. For the congruency effect, the schizophrenics showed significantly less activation in the same site of the left DLPFC in both the short-term and long-term latency conditions, as compared with the HC. For the latency effect, the regions of the left-side language network were over- or under-activated in the schizophrenics, as compared with the HC. Any interaction effect was not found for both the behavioral and fMRI results.

CONCLUSION

Our results indicate that the deficit in the left DLPFC is the core impairment of attentional processing in schizophrenics, regardless of other possible interactions such as the latency effect.