Marta Bosia

Functional and structural brain correlates of theory of mind and empathy deficits in schizophrenia

BACKGROUND Patients affected by schizophrenia show deficits in social cognition, with abnormal performance on tasks targeting theory of mind (ToM) and empathy (Emp). Brain imaging studies suggested that ToM and Emp depend on the activation of brain networks mainly localized at the superior temporal lobe and temporo-parietal junction. METHODS Participants included 24 schizophrenia patients and 20 control subjects. We used brain blood oxygen level dependent fMRI to study the neural responses to tasks targeting ToM and Emp. We then studied voxel-based morphometry of grey matter in areas where diagnosis influenced functional activation to both tasks. Outcomes were analyzed in the context of the general linear model, with global grey matter volume as nuisance covariate for structural MRI. RESULTS Patients showed worse performance on both tasks. We found significant effects of diagnosis on neural responses to the tasks in a wide cluster in right posterior superior temporal lobe (encompassing BA 22-42), in smaller clusters in left temporo-parietal junction and temporal pole (BA 38 and 39), and in a white matter region adjacent to medial prefrontal cortex (BA 10). A pattern of double dissociation of the effects of diagnosis and task on neural responses emerged. Among these areas, grey matter volume was found to be reduced in right superior temporal lobe regions of patients. CONCLUSIONS Functional and structural abnormalities were observed in areas affected by the schizophrenic process early in the illness course, and known to be crucial for social cognition, suggesting a biological basis for social cognition deficits in schizophrenia.

Influence of catechol-O-methyltransferase Val158Met polymorphism on neuropsychological and functional outcomes of classical rehabilitation and cognitive remediation in schizophrenia.

Neurocognitive deficits are recognized as core features of schizophrenia and have a great impact on functional outcome. Recent reports have suggested that a functional polymorphism, Val158Met, of the catechol-O-methyltransferase (COMT) gene, partially influences cognitive performances (mainly cognitive flexibility and working memory) both in schizophrenic patients and in healthy controls, probably by modulating prefrontal dopamine function. While previous studies focused on single evaluation of cognitive functioning, we aimed to analyse the additive effect of COMT genotype and cognitive exercise on dynamic modulation of cognitive performances. We analysed the COMT Val158Met polymorphism in 50 patients with chronic schizophrenia randomly allocated to two treatment conditions for 3 months: standard rehabilitation treatment (SRT) alone and SRT plus specific cognitive exercise of impaired functions. We then divided our sample in four subgroups on the basis of genotype (Val/Val versus Met carriers) and treatment (placebo versus active). We assessed patients with a neuropsychological battery, the Positive and Negative Symptoms Scale (PANSS) and the Quality of Life Scale (QLS) at enrolment, after 3 months of therapy and after further 3 months of follow-up. We found significantly greater improvement of cognitive flexibility performance and QLS total score for Met carriers on active treatment in comparison to Val/Val on placebo. The findings support the hypothesis that COMT polymorphism influences individual capacity to recover from cognitive deficit through rehabilitation therapy after a wider intervention also including deficit-specific cognitive exercise as a potentiating tool.

Cognitive dysfunction and glutamate reuptake: Effect of EAAT2 polymorphism in schizophrenia

A disturbance of glutamatergic transmission has been suggested to contribute to the development of schizophrenic pathophysiology, based primarily on the ability of glutamate receptor antagonists to induce schizophrenic-like symptoms. The excitatory amino acid transporter 2 (EAAT2) is responsible for the majority of glutamate uptake. It also contributes to energy metabolism in the brain, by transporting glutamate into astrocytes for conversion into glutamine. A dysregulation of its level of expression has been associated with multiple neurological disorders. Blocking glutamate uptake by EAAT2 in cultured oligodendrocytes leads to cell death, demyelination and axonal damage, suggesting that it is crucial for normal oligodendrocyte function. Different studies focused on EAAT2 alterations among subjects affected by schizophrenia, reporting a decreased expression in the parahippocampal region and in the dorsolateral prefrontal cortex. Moreover, subjects with the high-risk metabotropic glutamate receptor 3 (GRM3) haplotype associated with schizophrenia had lower EAAT2 expression in the prefrontal cortex and also showed impaired cognitive performances for measures of verbal list learning and verbal fluency. EAAT2 protein activity is regulated by a SNP rs4354668 (-181T/G) which falls in the gene promoter region, with the G allele resulting in a lower activity of the transporter. Based on these data, we assessed possible effects of the -181T/G EAAT2 polymorphism on two core prefrontal cognitive performances, known to be impaired in schizophrenia, in a sample of 211 clinically stabilized patients. We observed better executive functions (WCST, no. of categories) and working memory (N-back: 1-back, 2-back) performances in subjects homozygous for the T allele, compared to the G carriers group. These observations suggest that the presence of the G allele is associated, among patients with schizophrenia, with a disadvantageous effect on core cognitive functions that depend on prefrontal cortex activity. These results are preliminary and need to be replicated by future and larger studies, however they suggest that EAAT2 inefficiency may represent a target of interest for development of pharmacological strategies aimed to improve prefrontal performances by compensating the impaired glutamate reuptake.

HTTLPR functional polymorphism in schizophrenia: Executive functions vs. sustained attention dissociation

BACKGROUND Recently attention has been addressed to the role of 5-HT in cognition and several experimental studies revealed that manipulations of the central 5-HT system can produce quite specific changes in cognitive functioning. These results may suggest new treatment strategies to improve cognition in psychiatric conditions characterized by neuropsychological impairments, such as schizophrenia. It is possible to investigate the involvement of 5-HT in cognition by examining the impact of genetic variation in key regulators of serotoninergic neurotransmission. Among these, the serotonin transporter (5-HTT) presents a functional polymorphism in the transcriptional control region of the gene (5-HTTLPR) affecting transcriptional efficiency. In the present study, we aimed to analyze the effect of 5-HTTLPR polymorphism on specific cognitive functions, known to be affected by 5-HT manipulation and altered in schizophrenia. METHODS 223 schizophrenia patients were tested with Wisconsin Card Sorting Test (WCST), for the evaluation of cognitive flexibility, Continuous Performance Test (CPT), for the evaluation of attention, and genotyped for the 5-HTTLPR. RESULTS We found a significant association between HTT polymorphism and executive functions and inversely with sustained attention. The presence of the high-activity long (L) allele in homozygosis was a predictor of better executive performances and poorer performances of attention. CONCLUSIONS Our findings suggest that factors affecting serotonin availability may play a specific role in cognitive processes, probably through complex modulation of the different performance components.

Computer-aided neurocognitive remediation in schizophrenia: Durability of rehabilitation outcomes in a follow-up study

Cognitive deficits in patients with schizophrenia constitute a limiting factor to the chances of rehabilitation of daily living abilities, like personal and relational autonomy and working ability. Cognitive Remediation Therapy (CRT) is a rehabilitative technique that aims at the recovery of single cognitive functions through the execution of massive exercises of impaired cognitive domains. This study aims to establish if the results achieved through an intensive deficit-specific neurocognitive treatment of three months duration, were maintained over time. The sample consists in 100 patients diagnosed with schizophrenia according to the criteria of DSM IV. Patients were assessed on cognitive and daily functioning at baseline, after 3 months of either CRT or placebo training added to their standard rehabilitation treatment, at 6 month and 12-month follow-up. Results showed significant changes that were maintained at follow-up for executive function, attention and psychomotor coordination. Moreover the significant improvement in daily functioning was maintained at 6 and 12-month follow-up. In conclusion improvements in cognitive functions and daily functioning achieved through the association of CRT and standard rehabilitation treatment persist over time after the conclusion of the training period.

Neurofunctional correlates of theory of mind deficits in schizophrenia

Theory of Mind, the ability to understand the potential mental states and intentions of others, represents a relevant aspect of social cognition, with high impact on the capacity to interact within the social world. This very human ability has been one of the focuses of neuroscience research in the past decades and data from neuroimaging studies allowed to identify a Theory of Mind network and to formulate a neurobiological model. Concurrent neuropsychiatric studies showed that Theory of Mind is differently impaired in several conditions, among these, in schizophrenia, a disease characterized by functional and social disability. This paper addresses the issue of neurofunctional correlates of Theory of Mind deficits in schizophrenia, reviewing functional imaging studies of the past ten years comparing schizophrenia patients to healthy controls. Several differences in hemodynamic response between patients and controls were observed in the areas known to be critically involved in social cognition, such as the medial prefrontal cortex, temporal cortex surrounding superior temporal sulcus and temporo-parietal junction and cingulate cortex. Results are promising, however they are still heterogeneous. The reported variability could depend on factors related to the construct of Theory of Mind itself, technical aspects and psychopathological/physiopathological mechanisms and needs to be further addressed by future studies.

Effect of 5-HT1A-receptor functional polymorphism on Theory of Mind performances in schizophrenia

Theory of Mind (ToM) abilities are known to be impaired in schizophrenia and data from functional brain imaging studies showed that ToM deficit is correlated to prefrontal cortex (PFC) dysfunction. Moreover, several lines of evidence suggest a critical role for dopaminergic-serotoninergic interactions at the PFC level. In this view, we aimed to analyse the specific effect of the -1019C/G functional polymorphism of the serotonin 1A receptor (5-HT1A-R), involved in both serotonin and dopamine transmission regulation. A total of 118 clinically stabilised schizophrenia patients was assessed with a neuropsychological battery, including evaluation of IQ, verbal memory, attention and executive function and a ToM task; they also underwent 5-HT1A-R genotyping. We observed a significant effect of the 5-HT1A-R genotype on ToM performances, with the CC genotype performing significantly better. The finding suggests an effect of the 5-HT1A-R polymorphism on ToM cognitive performance in schizophrenia patients, probably through complex interactions between dopaminergic and serotoninergic systems, involved in mentalising.

The communicative impairment as a core feature of schizophrenia: Frequency of pragmatic deficit, cognitive substrates, and relation with quality of life

BACKGROUND Impairments in specific aspects of pragmatic competence, supporting the use of language in context, are largely documented in schizophrenia and might represent an indicator of poor outcome. Yet pragmatics is rarely included in clinical settings. This paper aims to promote a clinical consideration of pragmatics as a target of assessment and intervention. We investigated the frequency of the pragmatic deficit, its cognitive substrates, and the relation with quality of life. METHODS Pragmatic abilities were compared in a sample of patients with schizophrenia and healthy controls based on a comprehensive pragmatic test (APACS). We assessed also for psychopathology, cognition, social cognition, and quality of life. We explored the co-occurrence of deficits in different domains, and we used multiple regressions to investigate the effect of cognition and social cognition on pragmatics, and of pragmatics on quality of life. RESULTS Pragmatic abilities, especially comprehending discourse and non-literal meanings, were compromised in schizophrenia, with 77% of patients falling below cutoff. Pragmatic deficit co-occurred with cognitive or socio-cognitive deficits in approximately 30% of cases. Multiple regression analysis confirmed the interplay of cognition and social cognition in pragmatic behavior. Quality of life was predicted by symptoms and by pragmatic abilities. CONCLUSIONS The high frequency of impairment suggests that the pragmatic deficit is a core feature of schizophrenia, associated with quality of life. Cognitive and socio-cognitive abilities might represent necessary though not sufficient building blocks for the acquisition of pragmatic abilities throughout development. Therefore, a more precise incorporation of pragmatics in the description of the pathology is of high clinical and translational relevance.

Combined social cognitive and neurocognitive rehabilitation strategies in schizophrenia: neuropsychological and psychopathological influences on Theory of Mind improvement.

BACKGROUND Neurocognitive and social cognitive impairments represent important treatment targets in schizophrenia, as they are significant predictors of functional outcome. Different rehabilitative interventions have recently been developed, addressing both cognitive and psychosocial domains. Although promising, results are still heterogeneous and predictors of treatment outcome are not yet identified. In this study we evaluated the efficacy of two newly developed social cognitive interventions, respectively based on the use of videotaped material and comic strips, combined with domain-specific Cognitive Remediation Therapy (CRT). We also analysed possible predictors of training outcome, including basal neurocognitive performance, the degree of cognitive improvement after CRT and psychopathological variables. METHOD Seventy-five patients with schizophrenia treated with CRT, were randomly assigned to: social cognitive training (SCT) group, Theory of Mind Intervention (ToMI) group, and active control group (ACG). RESULTS ANOVAs showed that SCT and ToMI groups improved significantly in ToM measures, whereas the ACG did not. We reported no influences of neuropsychological measures and improvement after CRT on changes in ToM. Both paranoid and non-paranoid subjects improved significantly after ToMI and SCT, without differences between groups, despite the better performance in basal ToM found among paranoid patients. In the ACG only non-paranoid patients showed an improvement in non-verbal ToM. CONCLUSION Results showed that both ToMI and SCT are effective in improving ToM in schizophrenia with no influence of neuropsychological domains. Our data also suggest that paranoid symptoms may discriminate between different types of ToM difficulties in schizophrenia.

Patterns of evidence integration in schizophrenia and delusion

Previous studies documented a bias against disconfirmatory evidence (BADE) in patients affected by schizophrenia spectrum disorders, with some discrepant findings on its relationship with delusions. In order to further investigate the patterns of evidence integration in schizophrenia and delusion, we recruited 40 deluded and non-deluded patients with schizophrenia and 40 healthy control subjects. Participants were administered the BADE test, which consisted of 30 delusion-neutral scenarios, each one progressively described by three subsequent disambiguating statements and providing four types of interpretation to rate for plausibility; at every additional evidence presentation, participants were asked to adjust their ratings. In contrast to previous works, patients displayed both a BADE and a bias against confirmatory evidence (BACE) relative to healthy subjects, as they reduced plausibility ratings on incorrect interpretations and increased plausibility ratings on correct interpretation significantly less over trial progress. Moreover, BACE and BADE measures showed to discriminate differentially control from schizophrenia participants and delusional from non-delusional patients.