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.

Emotional reactivity in chronic schizophrenia: structural and functional brain correlates and the influence of adverse childhood experiences

BACKGROUND

Despite behavioural signs of flattened affect, patients affected by schizophrenia show enhanced sensitivity to negative stimuli. The current literature concerning neural circuitry for emotions supports dysregulations of cortico-limbic networks, but gives contrasting results. Adverse childhood experiences (ACEs) could persistently influence emotional regulation and neural correlates of response to emotional stimuli in healthy humans. This study evaluated the effect of ACEs and chronic undifferentiated schizophrenia on neural responses to emotional stimuli (negative facial expression).

METHOD

Brain blood-oxygen-level-dependent functional magnetic resonance imaging neural responses to a face-matching paradigm, and regional grey matter (GM) volumes were studied at 3.0 T in the amygdala, hippocampus, anterior cingulated cortex (ACC) and prefrontal cortex (PFC). The severity of ACEs was assessed. Participants included 20 consecutively admitted in-patients affected by chronic undifferentiated schizophrenia, and 20 unrelated healthy volunteers from the general population.

RESULTS

Patients reported higher ACEs than controls. Worse ACEs proportionally led to decreasing responses in the amygdala and hippocampus, and to increasing responses in the PFC and ACC in all participants. Patients showed higher activations in the amygdala and hippocampus, and lower activations in the PFC and ACC. Higher ACEs were associated with higher GM volumes in the PFC and ACC, and schizophrenia was associated with GM reduction in all studied regions.

CONCLUSIONS

Structural and functional brain correlates of emotional reactivity are influenced by both current chronic undifferentiated schizophrenia and the severity of past ACEs.