Psychosis is linked to aberrant salience or to viewing neutral stimuli as self-relevant, suggesting a possible impairment in selfrelevance processing. Psychosis is also associated with increased dopamine in the dorsal striatum, especially the anterior caudate (Kegeles et al., 2010). Critically, the anterior caudate is especially connected to (a) the cortical default mode network (DMN), centrally involved in self-relevance processing, and (b) to a lesser extent, the cortical frontoparietal network (FPN; Choi, Yeo, & Buckner, 2012). However, no previous study has directly examined striatal-cortical DMN connectivity in psychosis risk. In Study 1, we examined resting-state functional connectivity in psychosis risk (n = 18) and control (n = 19) groups between (a) striatal DMN and FPN subregions and (b) cortical DMN and FPN. The psychosis risk group exhibited decreased connectivity between the striatal subregions and the cortical DMN. In contrast, the psychosis risk group exhibited intact connectivity between the striatal subregions and the cortical FPN. Additionally, recent distress was also associated with decreased striatal-cortical DMN connectivity. In Study 2, to determine whether the decreased striatal-cortical DMN connectivity was specific to psychosis risk or was related to recent distress more generally, we examined the relationship between connectivity and distress in individuals diagnosed with nonpsychotic emotional distress disorders (N = 25). In contrast to Study 1, here we found that distress was associated with evidence of increased striatal-cortical DMN connectivity. Overall, the present results suggest that decreased striatal-cortical DMN connectivity is associated with psychosis risk and could contribute to aberrant salience.
The intrusion of associations into speech in schizophrenia disrupts coherence and comprehensibility, a feature of formal thought disorder referred to as loosened associations. We have previously proposed that loosened associations may result from hyperactivity in semantic association networks, leading to an increased frequency of associated words appearing in speech. Using Computed Associations in Sequential Text (CAST) software to quantify the frequency of such associations in speech, we have reported more frequent normative associations in language samples from patients with schizophrenia and in individuals with schizotypal characteristics. The present study further examined this deviance in schizophrenia by studying normative associations in those who share genes with an individual with schizophrenia, (i.e. first-degree relatives of probands with schizophrenia; HR) but who do not have an illness. Familial high-risk participants (n = 22), and controls (n = 24) provided verbal responses to cards from the Thematic Apperception Test. CAST analysis revealed that HR used more associated words in their speech compared to controls. Furthermore, the frequency of normative word associations was positively correlated with dimensional and total scores of schizotypy derived from ratings of the Structured Interview for Schizotypy, which confirms past research showing a relationship between schizotypy and hyperassociations. Our results suggest that language disturbances in schizophrenia likely arise from an underlying psychopathological mechanism, hyperactivity of semantic associations.
Smokers who regularly experience intense withdrawal symptoms, regardless of length of smoking abstinence, may be at heightened risk for experiencing panic attacks.
The 21st birthday celebration is characterized by extreme alcohol consumption. Accumulating evidence suggests that high-dose bingeing is related to structural brain changes and cognitive deficits. This is particularly problematic in the transition from adolescence to adulthood when the brain is still maturing, elevating the brain's sensitivity to the acute effects of alcohol intoxication. Heavy drinking is associated with reduced structural integrity in the hippocampus and corpus callosum and is accompanied by cognitive deficits. However, there is little research examining changes in the human brain related to discrete heavy-drinking episodes. The present study investigated whether alcohol exposure during a 21st birthday celebration would result in changes to white matter microstructure by utilizing diffusion tensor imaging measures and a quasi-experimental design. By examining structural changes in the brain from pre-to postcelebration within subjects (N ϭ 49) prospectively, we were able to more directly observe brain changes following an extreme-drinking episode. Region of interest analyses demonstrated increased fractional anisotropy in the posterior fornix (p Ͻ .0001) and in the body of the corpus callosum (p ϭ .0029) from pre-to postbirthday celebration. These results suggest acute white matter damage to the fornix and corpus callosum following an extreme-drinking episode, which is especially problematic during continued neurodevelopment. Therefore, 21st birthday drinking may be considered an important target event for preventing acute brain injury in young adults.
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