Schizophrenia bulletin
-
Schizophrenia bulletin · May 2013
Neural substrates of empathic accuracy in people with schizophrenia.
Empathic deficits in schizophrenia may lead to social dysfunction, but previous studies of schizophrenia have not modeled empathy through paradigms that (1) present participants with naturalistic social stimuli and (2) link brain activity to "accuracy" about inferring other's emotional states. This study addressed this gap by investigating the neural correlates of empathic accuracy (EA) in schizophrenia. ⋯ These results use a naturalistic performance measure to confirm that schizophrenic patients demonstrate impaired ability to understand others' internal states. They provide novel evidence about a potential mechanism for this impairment: schizophrenic patients failed to capitalize on targets' emotional expressivity and also demonstrate reduced neural sensitivity to targets' affective cues.
-
Schizophrenia bulletin · May 2013
Randomized Controlled Trial Multicenter StudyDopamine D2 receptor occupancy and cognition in schizophrenia: analysis of the CATIE data.
Antipsychotic drugs exert antipsychotic effects by blocking dopamine D2 receptors in the treatment of schizophrenia. However, effects of D2 receptor blockade on neurocognitive function still remain to be elucidated. The objective of this analysis was to evaluate impacts of estimated dopamine D2 receptor occupancy with antipsychotic drugs on several domains of neurocognitive function in patients with schizophrenia in the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) trial. ⋯ These findings suggest a nonlinear relationship between prescribed antipsychotic doses and overall neurocognitive function and vigilance. This study shows that D2 occupancy above approximately 80% not only increases the risk for extrapyramidal side effects as consistently reported in the literature but also increases the risk for cognitive impairment.
-
Schizophrenia bulletin · Mar 2013
Subanaesthetic ketamine treatment alters prefrontal cortex connectivity with thalamus and ascending subcortical systems.
Acute treatment with subanaesthetic doses of NMDA receptor antagonists, such as ketamine, provides a translational model with relevance to many of the symptoms of schizophrenia. Previous studies have focused specifically on the prefrontal cortex (PFC) because this region is implicated in many of the functional deficits associated with this disorder and shows reduced activity (hypofrontality) in schizophrenia patients. Chronic NMDA antagonist treatment in rodents can also induce hypofrontality, although paradoxically acute NMDA receptor antagonist administration induces metabolic hyperfrontality. ⋯ Together with other emerging data, these findings suggest that the reticular nucleus of the thalamus, along with the diffusely projecting subcortical aminergic/cholinergic systems, represent a primary site of action for ketamine in reproducing the diverse symptoms of schizophrenia. Our results also demonstrate the added scientific insight gained by characterizing the functional connectivity of discrete brain regions from brain imaging data gained in a preclinical context.
-
Schizophrenia bulletin · Jan 2013
N-acetylaspartylglutamate (NAAG) and N-acetylaspartate (NAA) in patients with schizophrenia.
BACKGROUND : Imbalance of glutamatergic neurotransmission has been proposed as a key mechanism underlying symptoms of schizophrenia. The neuropetide N-acetylaspartylglutamate (NAAG) modulates glutamate release. NAAG provides a component of the proton magnetic resonance spectrum (1H-MRS) in humans. The signal of NAAG, however, largely overlaps with its precursor and degrading product N-acetylaspartate (NAA) that by itself does not act in glutamatergic neurotransmission. ⋯ In this study, we present the first in vivo evidence for altered NAAG concentration in patients with schizophrenia.
-
Schizophrenia bulletin · Nov 2012
Meta AnalysisWhite matter development in adolescence: diffusion tensor imaging and meta-analytic results.
In light of the evidence for brain white matter (WM) abnormalities in schizophrenia, study of normal WM maturation in adolescence may provide critical insights relevant to the neurodevelopment of the disorder. Voxel-wise diffusion tensor imaging (DTI) studies have consistently demonstrated increases in fractional anisotropy (FA), a putative measure of WM integrity, from childhood into adolescence. However, the WM tracts that show FA increases have been variable across studies. Here, we aimed to assess which WM tracts show the most pronounced changes across adolescence. ⋯ These data highlight increasing connectivity in the SLF during adolescence. In light of evidence for compromised SLF integrity in high-risk and first-episode patients, these data suggest that abnormal maturation of the SLF during adolescence may be a key target in the neurodevelopment of schizophrenia.