From Semantic to Social Deficits: Dysfunction of the Nondominant Posterior Perisylvian Area in Schizophrenia

Schizophrenia is characterized by profound deficits in social competence and functioning, independent from active psychotic symptoms at different stages of the disease. Social deficits in schizophrenia are clinically well characterized, but their neurobiological underpinnings are undetermined. This article reviews recent evidence supporting heritable deficits in a circuit necessary for appropriate naming of emotions and mental states in others, centered at the temporoparietal junction of the nondominant hemisphere. The clinical implications of this model are discussed, including the potential use of rehabilitation techniques oriented to recognition and naming of emotions and mental states as a necessary step for social rehabilitation.

Pattern of brain activation during social cognitive tasks is related to social competence in siblings discordant for schizophrenia

Measures of social competence are closely related to actual community functioning in patients with schizophrenia. However, the neurobiological mechanisms underlying competence in schizophrenia are not fully understood. We hypothesized that social deficits in schizophrenia are explained, at least in part, by abnormally lateralized patterns of brain activation in response to tasks engaging social cognition, as compared to healthy individuals. We predicted such patterns would be partly heritable, and therefore affected in patients' nonpsychotic siblings as well. We used a functional magnetic resonance image paradigm to characterize brain activation induced by theory of mind tasks, and two tests of social competence, the Test of Adaptive Behavior in Schizophrenia (TABS), and the Social Skills Performance Assessment (SSPA) in siblings discordant for schizophrenia and comparable healthy controls (n = 14 per group). Healthy individuals showed the strongest correlation between social competence and activation of right hemisphere structures involved in social cognitive processing, whereas in patients, the correlation pattern was lateralized to left hemisphere areas. Unaffected siblings of patients exhibited a pattern intermediate between the other groups. These results support the hypothesis that schizophrenia may be characterized by an abnormal functioning of nondominant hemisphere structures involved in the processing of socially salient information.

Activation of brain areas concerned with social cognition during moral decisions is abnormal in schizophrenia patients and unaffected siblings

Moral decision-making involves complex social cognitive processes which are known to be altered in patients with schizophrenia and first-degree relatives. Traditional philosophical views on human moral behavior have distinguished between utilitarian views (which emphasize outcomes) and deontological approaches (defining what is right to do according to certain norms). Since emotions have been suggested to play a determining role in moral behavior, we hypothesized patients with schizophrenia and unaffected siblings would make more utilitarian choices and show faulty activation of brain areas concerned with emotion regulation during such tasks. Unexpectedly, all participants (n = 13 per group) made the same proportion of utilitarian and deontological decisions. Brain activation common to all groups induced by moral decisions included two circumscribed portions of right ventromedial and dorsolateral prefrontal cortex, adding to previous evidence on a right prosencephalic cognitive network involved in ethical decisions. However, brain activation induced by moral decisions was different in healthy persons, schizophrenia patients, and nonpsychotic siblings in regards to areas directly concerned with emotion processing. These results seem to underscore the role of acquired norms in moral decisions, a frequently overlooked concept in the neurobiological characterization of human ethical behavior, and add to previous evidence of abnormal social cognitive processing in schizophrenia.

Decreased activity in right-hemisphere structures involved in social cognition in siblings discordant for schizophrenia

BACKGROUND

Social cognitive deficits contribute to functional disability in schizophrenia. Social cognitive tasks in healthy persons consistently evoke activation of medial prefrontal cortex, inferior frontal gyrus, temporoparietal gyrus, and posterior cingulate cortex/precuneus. We tested the hypothesis that patients with schizophrenia and their unaffected siblings share dysfunction of the same neural networks.

METHODS

Neural activation during emotion processing (EP), theory of mind (ToM), and control tasks was measured using functional magnetic resonance imaging (fMRI) in 14 patients with schizophrenia, 14 nonpsychotic siblings of patients with schizophrenia, and 14 matched healthy subjects.

RESULTS

Compared with healthy controls, patients with schizophrenia showed reduced activation of right hemisphere structures involved in EP and ToM including inferior frontal gyrus, middle frontal gyrus, and right temporoparietal junction. These deficits were shared, in part, by unaffected siblings. The latter group demonstrated deficits in bilateral precuneus activation during ToM, not present in patients.

CONCLUSIONS

Schizophrenia appears to be associated with a deficit in activation of right hemisphere components of a ToM network. Such deficits are shared in part by those at high genetic risk but unaffected by schizophrenia.

Emotion processing and theory of mind in schizophrenia patients and their unaffected first-degree relatives

Previous studies have suggested that social cognition is affected in individuals with schizophrenia. The purpose of this study was to explore to what extent social cognition deficits are shared by unaffected first-degree relatives, and the nature of the relationship between performance in different paradigms of social cognition. 20 Schizophrenia patients (7 females, 31+/-10 years), 20 healthy age- and gender-matched individuals, 20 unaffected first-degree relatives of the schizophrenia patients (11 females, 50+/-20 years), and 20 healthy individuals matched for age and gender were recruited. Patients showed deficits in the detection of social Faux Pas (0.80+/-0.17 vs. controls: 0.94+/-0.09, p=0.025) and the correct identification of Theory of Mind stories (0.71+/-0.13 vs. controls: 0.82+/-0.12, p=0.038). Relatives performed poorly in the Faces Test (0.83+/-0.14 vs. controls: 0.9+/-0.08, p=0.048), the Reading the Mind in the Eyes Test (0.59+/-0.17 vs. controls: 0.71+/-0.14, p=0.046) and the detection of social Faux Pas (0.8+/-0.2 vs. controls: 0.93+/-0.09, p=0.024). Abnormalities were independent of age, years of education, and general cognitive performance in patients and their relatives. Performance in an Emotion Processing task (Faces Test) was correlated with performance in theory of mind tests in healthy individuals and relatives of patients with schizophrenia only. These results suggest that schizophrenia patients and their unaffected first-degree relatives display similar but nonidentical patterns of social cognition processing.

Heart rate variability response to mental arithmetic stress is abnormal in first-degree relatives of individuals with schizophrenia

BACKGROUND

Schizophrenia patients exhibit an abnormal autonomic response to mental stress. We sought to determine the cardiac autonomic response to mental arithmetic stress in their unaffected first-degree relatives.

METHODS

Heart rate variability (HRV) analysis was performed on recordings obtained before, during, and after a standard mental arithmetic task to induce mental stress. 22 unaffected first-degree relatives of patients meeting DSM-IV criteria for schizophrenia (R) and 22 healthy individuals (C) were included in this study.

RESULTS

Patients' relatives (R) had a normal response to the mental arithmetic stress test, showing an increased heart rate compared with controls. They also displayed the characteristic pattern of relative contributions of HRV components that consists of increased low-frequency (LF) HRV and decreased high-frequency (HF) HRV. Recovery of the resting pattern of HRV immediately after stress termination was observed in healthy subjects (LF 62+/-16% vs. 74+/-10% , HF 37+/-16% vs. 25+/-10%, F=9.616, p=0.004), but not in patients' relatives (LF 60+/-19% vs. 70+/-13%, HF 40+/-19% vs. 29+/-13%, F=8.4, p=0.056).

CONCLUSIONS

First-degree relatives of schizophrenia patients exhibit an abnormal pattern of protracted response to mental arithmetic stress, though less intense than that observed in patients in a previous study. This suggests that a pattern of autonomic response to stress may therefore be familial and heritable.

Heart rate variability response to mental arithmetic stress in patients with schizophrenia: autonomic response to stress in schizophrenia

BACKGROUND

The vulnerability-stress hypothesis is an established model of schizophrenia symptom formation. We sought to characterise the pattern of the cardiac autonomic response to mental arithmetic stress in patients with stable schizophrenia.

METHODS

We performed heart rate variability (HRV) analysis on recordings obtained before, during, and after a standard test of autonomic function involving mental stress in 25 patients with DSM-IV schizophrenia (S) and 25 healthy individuals (C).

RESULTS

Patients with schizophrenia had a normal response to the mental arithmetic stress test. Relative contributions of low-frequency (LF) HRV and high-frequency (HF) HRV influences on heart rate in patients were similar to controls both at rest (LF 64+/-19% (S) vs. 56+/-16% (C); HF 36+/-19% (S) vs. 44+/-16% (C), t=1.52, p=0.136) and during mental stress, with increased LF (S: 76+/-12%, C: 74+/-11%) and decreased HF (S: 24+/-12%, C: 26+/-11%) in the latter study condition. Whilst healthy persons recovered the resting pattern of HRV immediately after stress termination (LF 60+/-15%, HF 40+/-15%, F=18.5, p<0.001), in patients HRV remained unchanged throughout the observed recovery period, with larger LF (71+/-17%) and lower HF (29+/-17%) compared with baseline (F=7.3, p=0.013).

CONCLUSIONS

Patients with schizophrenia exhibit a normal response to the mental arithmetic stress test as a standard test of autonomic function but in contrast with healthy individuals, they maintain stress-related changes of cardiac autonomic function beyond stimulus cessation.