The impact of traumatic stress on Pavlovian biases.

BACKGROUND: Disturbances in Pavlovian valuation systems are reported to follow traumatic stress exposure. However, motivated decisions are also guided by instrumental mechanisms, but to date the effect of traumatic stress on these instrumental systems remain poorly investigated. Here, we examine whether a single episode of severe traumatic stress influences flexible instrumental decisions through an impact on a Pavlovian system. METHODS: Twenty-six survivors of the 2011 Norwegian terror attack and 30 matched control subjects performed an instrumental learning task in which Pavlovian and instrumental associations promoted congruent or conflicting responses. We used reinforcement learning models to infer how traumatic stress affected learning and decision-making. Based on the importance of dorsal anterior cingulate cortex (dACC) for cognitive control, we also investigated if individual concentrations of Glx (=glutamate + glutamine) in dACC predicted the Pavlovian bias of choice. RESULTS: Survivors of traumatic stress expressed a greater Pavlovian interference with instrumental action selection and had significantly lower levels of Glx in the dACC. Across subjects, the degree of Pavlovian interference was negatively associated with dACC Glx concentrations. CONCLUSIONS: Experiencing traumatic stress appears to render instrumental decisions less flexible by increasing the susceptibility to Pavlovian influences. An observed association between prefrontal glutamatergic levels and this Pavlovian bias provides novel insight into the neurochemical basis of decision-making, and suggests a mechanism by which traumatic stress can impair flexible instrumental behaviours.

Verbal and nonverbal memory in school-aged children born to opioid-dependent mothers.

BACKGROUND: The potential long-term developmental effects of prenatal methadone and buprenorphine exposure during pregnancy are still largely unknown. AIMS: We investigated memory function in school-aged children of women enrolled in opioid maintenance therapy (OMT) during pregnancy. STUDY DESIGN: Prospective longitudinal cohort study. SUBJECTS: Participants included 41 children (aged 9-11 years), 20 of which had histories of prenatal methadone or buprenorphine exposure. OUTCOME MEASURES: Verbal and non-verbal memory function was assessed using four subtests from the Test of Memory and Learning - Second edition (TOMAL-2). RESULTS: The OMT group scored lower on both the two non-verbal as well as the two verbal memory tasks, all p-values <.05. Group differences remained for three out of the four subtests after controlling for general IQ. Including maternal tobacco use during pregnancy increased the explanatory power of the model, R2 change of 0.07, p = .04. CONCLUSIONS: Children prenatally exposed to methadone or buprenorphine had significantly lower memory performance, however, this association may in part be explained by maternal tobacco use during pregnancy. Consequently, smoking cessation programs should be systematically integrated into opioid maintenance therapy programs for pregnant women.

Executive functions are impaired in adolescents engaging in non-suicidal self-injury.

BACKGROUND: The aim of this study was to investigate three main aspects of executive functions (EFs), i.e. shifting, updating and inhibition, in adolescents engaging in non-suicidal self-injury (NSSI) as compared with healthy controls. METHOD: EFs were assessed using the Intra/Extradimensional Set Shift, the Spatial Working Memory (SWM) Test and the Stop Signal Test (SST) from the Cambridge Neuropsychological Test Automated Battery (CANTAB), in a high-severity NSSI group (n=33), a low-severity NSSI group (n=29) and a healthy control group (n=35). Diagnostic characteristics were examined using the Kiddie-Sads-Present and Lifetime Version. RESULTS: There were group differences on the SWM Test. A trend towards an interaction effect of sex revealed that males in the high-severity NSSI group made significantly more errors than males and females in the control group. Both males and females in the high-severity NSSI group made poor use of an efficient strategy in completing the test. The low-severity NSSI group performed poorly on the SST, making more errors than the control group and showing an impaired ability to inhibit initiated responses, as compared with the high-severity NSSI group. There were group differences in frequencies of current and previous major depressive disorder. However, no effects of these diagnoses were found on any of the EF tests. CONCLUSIONS: This study demonstrates that NSSI subgroups have distinct deficits in EFs. The high-severity NSSI group has working memory deficits, while the low-severity NSSI group has impaired inhibitory control. This supports the emotion regulation hypothesis.