Karyne Anselmo

Theory of mind and context processing in schizophrenia: the role of cognitive flexibility.

The present study sought to identify whether cognitive flexibility and context processing may impact theory of mind (ToM) ability in schizophrenia. Thirty two patients with schizophrenia and 29 matched healthy participants were tested individually on their ToM ability using a task involving attribution and comprehension of a speakers ironic intent. This task made it possible to determine whether the degree of incongruity between contextual information and a target sentence has an impact on the attribution of ironic intent to the protagonists of a story. Participants were also assessed on their cognitive flexibility and working memory. The main results revealed that participants with schizophrenia correctly perceived contextual information cueing attribution of ironic intent to the protagonist of the stimulus, but they showed difficulty to correctly integrate this information, performing significantly worse than healthy participants when they attributed mental states. However, some participants with schizophrenia performed like healthy control participants on the ToM task while others did not. A lack of flexibility seems to differentiate the two schizophrenia subgroups thereby obtained, suggesting that cognitive flexibility has an impact on ToM performances in schizophrenia. These difficulties were not associated with clinical symptoms. Such results will have an impact on cognitive remediation.

Neural changes associated with appetite information processing in schizophrenic patients after 16 weeks of olanzapine treatment

There is evidence that some atypical antipsychotics, including olanzapine, can produce unwanted metabolic side effects, weight gain and diabetes. However, neuronal correlates of change related to food information processing have not been investigated with these medications. We studied the effect of a pharmacological manipulation with an antipsychotic known to cause weight gain on metabolites, cognitive tasks and neural correlates related to food regulation. We used functional magnetic resonance imaging in conjunction with a task requiring visual processing of appetitive stimuli in schizophrenic patients and healthy controls before and after 16 weeks of antipsychotic medication with olanzapine. In patients, the psychological and neuronal changes associated following the treatment correlated with appetite control measures and metabolite levels in fasting blood samples. After 16 weeks of olanzapine treatment, the patients gained weight, increased their waist circumference, had fewer positive schizophrenia symptoms, a reduced ghrelin plasma concentration and an increased concentration of triglycerides, insulin and leptin. In premotor area, somatosensory cortices as well as bilaterally in the fusiform gyri, the olanzapine treatment increased the neural activity related to appetitive information in schizophrenic patients to similar levels relative to healthy individuals. However, a higher increase in sensitivity to appetitive stimuli after the treatment was observed in insular cortices, amygdala and cerebellum in schizophrenic patients as compared with healthy controls. Furthermore, these changes in neuronal activity correlated with changes in some metabolites and cognitive measurements related to appetite regulation.

Neuronal correlates of appetite regulation in patients with schizophrenia: Is there a basis for future appetite dysfunction?

BACKGROUND Given the undesired metabolic side effects of atypical antipsychotic medication it is important to understand the neuronal basis related to processing of appetite regulation in patients affected by schizophrenia. METHODS Here we used functional magnetic resonance imaging (fMRI) to assess brain activity in response to food cues and neutral stimuli in twenty patients with schizophrenia and eleven healthy individuals. In addition to clinical and dietary habits assessments, we collected, in patients, measurements of fasting glucose, ghrelin, leptin, insulin, prolactin and lipids blood concentration and we correlated the cerebral activity with clinical and metabolic measures. RESULTS Both groups engaged a common neuronal network while processing food cues, which included the left insula, primary sensorimotor areas, and inferior temporal and parietal cortices. Cerebral responses to appetitive stimuli in thalamus, parahippocampus and middle frontal gyri were specific only to schizophrenic patients, with parahippocampal activity related to hunger state and increasing linearly over time. Antipsychotic medication dosage correlated positively with a cognitive measure reflecting food cravings, whereas the severity of the disease correlated negatively with a cognitive measure indicating dietary restraint in eating habits. These cognitive variables correlated, in turn, with parahippocampal and thalamic neuronal activities, respectively. CONCLUSIONS We identified a specific neural substrate underlying cognitive processing of appetitive stimuli in schizophrenia, which may contribute to appetite dysfunction via perturbations in processing of homeostatic signals in relation to external stimuli. Our results also suggest that both antipsychotic medication and the disease severity per se could amplify these effects, via different mechanisms and neuronal networks.

INCREASED LIMBIC SYSTEM ACTIVITY ASSOCIATED WITH APPETITE DYSFUNCTION IN SCHIZOPHRENIC PATIENTS FOLLOWING AN OLANZAPINE TREATMENT

(DLPFC, BA10) to perform the context processing task, reflecting inefficiency. In patients there are frontal activity differences according to the genotype, with met carriers activating more DLPFC (left BA47, right BA 45) and anterior cingulate (BA32) than val carriers. Discussion: COMT genotype exerts little impact on neuropsychological functions. Differences in cognitive performance across groups are reliably measured by the MATRICS Consensus Cognitive battery, however this instrument seems to be not sensitive enough to capture COMT genotype effects. Specific cognitive domains (context processing) are more sensitive to COMT genotype effects. Although patients with schizophrenia spectrum disorder exhibit more prominent deficits in context processing, these deficits are also seen in their relatives. The DPX task, which assesses context processing, is sensitive to COMT genotype in patients. Val/val carriers exhibit more contex processing impairment than met/met carriers, probably due to less dopamine availability in the PFC. Prefrontal brain activity of context processing deficits in schizophrenia may be mediated by COMT genotype effects.

12 – Olanzapine and cerebral mechanism involved in appetite and weight gain in schizophrenia: An fMRI study

impaired SCZ subjects, more than half showed a decline from premorbid level, compared to one third of the cognitively impaired BP group. Of the neuropsychologically unimpaired subjects, 7% SCZ and 3% BP showed signs of reduced IQ performance from premorbid level. Conclusions: Neuropsychologically impairment is confirmed to be more frequent in SCZ than in BP subjects, although more then half of the SCZ and two-thirds BP subjects did not evidence any neurocognitive difficulties. Support for premorbid impairment as well as a worsening of cognitive performance was found in both groups. The study thus supports a combined neurodevelopmental and neurodegenerative model for cognitive impairment.

Do patients with schizophrenia attribute intention and belief in a referential communication task

preference and performance abilities, a cross-sectional sample of 548 children (ages 3–18) and adults (over 19) completed the Waterloo Handedness Questionnaire, the WatHand Cabinet Test (an observational test of hand preference), and the Annett pegboard. Findings revealed that while the direction of hand preference does not change significantly with age, the degree of hand preference does, such that younger children exhibit weaker hand preference than older children and adults. This pattern of hand preference was much more evident for lefthanded individuals, where consistent hand preference was not seen until 8 years of age. Similarly, performance differences between the hands did not emerge for left-handers until later childhood, while in comparison large performance differences were seen for right-handers at all ages. The implications for the development of handedness will be discussed.