Search

Background: Previously identified resting functional connectivity (FC) differences in individuals with stimulant use disorder (SUD) suggest an imbalance in neural regions that mediate behavioral aspects relevant to addiction such as emotion regulation and reward processing. There is a need to further investigate these differences across time between those that relapse and those that do not. This is the first longitudinal study of recently abstinent SUD (SUD-RA) that identifies specific FC changes in subsequent relapsers (vs abstainers). We hypothesized that (1) subsequent relapsers (vs abstainers) will show lower FC of emotion regulation regions and higher FC of reward processing regions and (2) FC differences would be more evident across time. Methods: We examined resting FC in 18 SUD-RAs (8 females, age: M =22.05±2.64) and 15 non-substance abusing controls (NSAC; 5 females, age: M =24.21±5.76) at Time 1 (abstinent ∼5 weeks). Fourteen NSAC and 12 SUD-RAs were re-examined at Time 2 (abstinent ∼13 weeks). With seed-based FC measures, we examined FC differences between SUD-RAs that abstained or relapsed over the subsequent 6 months. Results: Relapsers (vs abstainers) had higher FC between (1) nucleus accumbens (NAcc) and left frontopolar cortex (FPC), (2) NAcc and posterior cingulate gyrus and (3) subgenual anterior cingulate and left FPC at Time 1. Relapsers (vs abstainers) showed larger reduction in FC strength within these regions across time. Conclusions: Resting FC reduction found in relapsers (vs. abstainers) from 5 to 13 weeks of abstinence may be a biological marker of relapse vulnerability. These preliminary findings require replication with larger sample sizes. [ABSTRACT FROM AUTHOR]

Background: Functional neuroimaging studies suggest that chronic cocaine use is associated with frontal lobe abnormalities. Functional connectivity (FC) alterations of cocaine-dependent individuals (CD), however, are not yet clear. This is the first study to our knowledge that examines resting FC of anterior cingulate cortex (ACC) in CD. Because ACC is known to integrate inputs from different brain regions to regulate behavior, we hypothesized that CD will have connectivity abnormalities in ACC networks. In addition, we hypothesized that abnormalities would be associated with poor performance in delayed discounting and reversal learning tasks. Methods: Resting functional magnetic resonance imaging data were collected to look for FC differences between 27 CD (5 women, age: M = 39.73, SD = 6.14 years) and 24 control subjects (5 women, age: M = 39.76, SD = 7.09 years). Participants were assessed with delayed discounting and reversal learning tasks. With seed-based FC measures, we examined FC in CD and control subjects within five ACC connectivity networks with seeds in subgenual, caudal, dorsal, rostral, and perigenual ACC. Results: The CD showed increased FC within the perigenual ACC network in left middle frontal gyrus, ACC, and middle temporal gyrus when compared with control subjects. The FC abnormalities were significantly positively correlated with task performance in delayed discounting and reversal learning tasks in CD. Conclusions: The present study shows that participants with chronic cocaine-dependency have hyperconnectivity within an ACC network known to be involved in social processing and “mentalizing.” In addition, FC abnormalities found in CD were associated with difficulties with delay rewards and slower adaptive learning. [ABSTRACT FROM AUTHOR]

Abstract: Persecutory delusions, a common symptom of schizophrenia, involve a disruption in the way that patients determine the intentions of others and especially their trustworthiness. However, it is unclear to what extent general preference affects trustworthiness judgments in patients with schizophrenia and how that relates to paranoid symptomology. Patients with schizophrenia and control subjects rated unfamiliar faces for trustworthiness and attractiveness (as a proxy for preference). The results demonstrate that patients do not show an overall difference in their trustworthiness ratings of unfamiliar faces. However, they do show a significant reduction in the correlation between trustworthiness and other indicators of preference, in this case, attractiveness judgments. The level of persecutory delusions is associated with this effect, such that patients with low levels of delusions show correlations near that of normal controls and high levels of persecutory delusions are related to a reduced trust/attractiveness correlation. These results suggest that patients with schizophrenia suffering from persecutory delusions rely less on normative social cues when making interpersonal judgments. Such findings underscore the importance of examining symptom-specific information when studying trust in patients with schizophrenia. [ABSTRACT FROM AUTHOR]

Background: The predisposition, or diathesis, to schizophrenia is highly heritable. The manner in which this genetic diathesis is manifest in the central nervous system is largely unknown, although healthy relatives of schizophrenia patients show executive processing deficits associated with prefrontal cortical impairments. Methods: The current study evaluated brain activity in 21 healthy relatives of schizophrenia patients and 20 demographically similar control subjects during correct trials on a stimulus-response incompatibility task. During the first part of each trial, participants represented and maintained the instruction for that trial; during the second part, participants used the instruction either to make an automatic response or to overcome this prepotent response. Results: Behaviorally, relatives were slower when overcoming the prepotent response. Analyses focused on the first part of the trial indicated that both groups showed activity in middle frontal (Brodmann areas 46 and 9) and anterior cingulate (Brodmann area 32) gyri. However, control subjects showed significantly greater activity in dorsal prefrontal cortex (Brodmann areas 9, 8, and 6) when preparing to overcome the prepotent response, whereas patients’ relatives showed prefrontal activity later, when making the response. Conclusions: Using an event-related design showed distinct prefrontal brain abnormalities associated with the genetic diathesis to schizophrenia. [Copyright &y& Elsevier]

Abstract: One of the fundamental goals in understanding schizophrenia is linking the observable symptoms to the underlying unobservable pathophysiology. Given recent advances in medical imaging, researchers are increasingly investigating brain-behavior relationships to better understand the neural substrates of negative, positive, and disorganization symptoms in schizophrenia. This review focused on 25 task-related functional magnetic resonance imaging studies and found meaningful small to moderate associations between specific symptom dimensions and regional brain activity. Negative symptoms were related to the functioning of the ventrolateral prefrontal cortex and ventral striatum. Positive symptoms, particularly persecutory ideation, were related to functioning of the medial prefrontal cortex, amygdala, and hippocampus/parahippocampal region. Disorganization symptoms, although less frequently evaluated, were related to functioning of the dorsolateral prefrontal cortex. Surprisingly, no symptom domain had a consistent relationship with the middle or superior temporal regions. While a number of adaptations in experimental design and reporting standards can facilitate this work, current neuroimaging approaches appear to provide a number of consistent links between the manifest symptoms of schizophrenia and brain dysfunction. [Copyright &y& Elsevier]

Abstract: How do personality measures of suspiciousness correspond to experimental measures of trust? Eighty-two subjects responded in an experimental paradigm that distinguished a suspicious decision-making condition from rational mistrust and risk aversion. Subjects in the Minnesota trust game were anonymously paired and chose between an assured payoff and a payoff determined by a partner or a coin flip. We found that subjects high on the alienation subscale of the multidimensional personality questionnaire () were less trusting even when their partner had no monetary incentive to penalize them. However, subjects high on harm avoidance chose the uncertain payoff less when a coin flip determined their payment. These findings suggested that the mental processes associated with suspiciousness were qualitatively different from those related to risk aversion and rational mistrust and served to validate the Minnesota trust game as a measure of individual differences in suspicious decision-making biases. [Copyright &y& Elsevier]

Abstract: Although regional brain abnormalities underlying spatial working memory (SWM) deficits in schizophrenia have been identified, little is known about which brain circuits are functionally disrupted in the SWM network in schizophrenia. We investigated SWM-related interregional functional connectivity in schizophrenia using functional magnetic resonance imaging (fMRI) data collected during a memory task that required analysis of spatial information in object structure. Twelve schizophrenia patients and 11 normal control subjects participated. Patients had SWM performance deficits and deficient neural activation in various brain areas, especially in the high SWM load condition. Examination of the covariation of regional brain activations elicited by the SWM task revealed evidence of functional disconnection between prefrontal and posterior visual association areas in schizophrenia. Under low SMW load, we found reduced functional associations between dorsolateral prefrontal cortex (DLPFC) and inferior temporal cortex (ITC) in the right hemisphere in patients. Under high SWM load, we found evidence for further functional disconnection in patients, including additional reduced functional associations between left DLPFC and right visual areas, including the posterior parietal cortex (PPC), fusiform gyrus, and V1, as well as between right inferior frontal cortex and right PPC. Greater prefrontal–posterior cortical functional connectivity was associated with better SWM performance in controls, but not in patients. These results suggest that prefrontal–posterior functional connectivity associated with the maintenance and control of visual information is central to SWM, and that disruption of this functional network underlies SWM deficits in schizophrenia. [Copyright &y& Elsevier]