Blockade of cue-induced brain activation of abstinent alcoholics by a single administration of amisulpride as measured with fMRI

BACKGROUND: Once alcohol dependence is established, alcohol-associated cues may induce dopamine release in the reward system, which is accompanied by alcohol craving and may lead to relapse. In cocaine addicts, dopamine release in the thalamus was positively correlated with cocaine craving. We tested the effects of the atypical dopamine D(2/3) blocker amisulpride on cue-induced brain activation in a functional magnetic resonance imaging (fMRI) paradigm. METHODS: Alcohol-associated and neutral pictures were presented in a block design to 10 male abstinent alcoholics (1-3 weeks after detoxification) and 10 healthy men during fMRI. The fMRI scans were acquired before and 2 hours after the oral application of 400 mg amisulpride. Before and after each scan, alcohol craving was measured with visual analogue scales. RESULTS: Before the application of amisulpride, alcohol versus control cues elicited a higher blood oxygen level-dependent (BOLD) signal in the left frontal and orbitofrontal lobe, left cingulate gyrus, bilateral parietal lobe, and bilateral hippocampus in alcoholics compared with healthy controls. After amisulpride, alcoholics showed a reduced activation in the right thalamus compared with the first scan. Alcoholics no longer showed significant differences in their cue-elicited BOLD response after amisulpride medication compared with medication-free controls. Self-reported craving was not affected by amisulpride medication. CONCLUSIONS: Amisulpride medication was associated with reduced cue-induced activation of the thalamus, a brain region closely connected with frontostriatal circuits that regulate behavior and may influence relapse risk.     

Altered cortisol awakening response in posttraumatic stress disorder

An altered function of the hypothalamic-pituitary-adrenal axis is assumed to be characteristic for Posttraumatic Stress Disorder (PTSD), although there is inconsistent empirical evidence. Only few studies examined the awakening cortisol response and a daytime profile in PTSD. Salivary cortisol levels were measured at seven intervals from awakening until 8 PM in trauma-exposed subjects with (N=29) and without PTSD (N=19) and in 15 non-exposed controls. While the three groups did not differ with respect to their first cortisol level immediately after awakening, the expected cortisol increase to awakening 15-60 min later was significantly lower in PTSD patients compared to non-PTSD subjects and healthy controls. This effect remained stable when trauma-exposed subjects with comorbid major depression were excluded from the analysis. A significant negative correlation between the overall cortisol secretion (AUC(G)) and overall PTSD symptomatology and hyper-arousal symptoms was found. The findings are discussed in light of the hypothesis of a counterregulation of hyper-arousal symptoms and chronic stress in PTSD.     

A target sample of adolescents and reward processing: same neural and behavioral correlates engaged in common paradigms?

Adolescence is a transition period that is assumed to be characterized by increased sensitivity to reward. While there is growing research on reward processing in adolescents, investigations into the engagement of brain regions under different reward-related conditions in one sample of healthy adolescents, especially in a target age group, are missing. We aimed to identify brain regions preferentially activated in a reaction time task (monetary incentive delay (MID) task) and a simple guessing task (SGT) in a sample of 14-year-old adolescents (N?=?54) using two commonly used reward paradigms. Functional magnetic resonance imaging was employed during the MID with big versus small versus no win conditions and the SGT with big versus small win and big versus small loss conditions. Analyses focused on changes in blood oxygen level?Cdependent contrasts during reward and punishment processing in anticipation and feedback phases. We found clear magnitude-sensitive response in reward-related brain regions such as the ventral striatum during anticipation in the MID task, but not in the SGT. This was also true for reaction times. The feedback phase showed clear reward-related, but magnitude-independent, response patterns, for example in the anterior cingulate cortex, in both tasks. Our findings highlight neural and behavioral response patterns engaged in two different reward paradigms in one sample of 14-year-old healthy adolescents and might be important for reference in future studies investigating reward and punishment processing in a target age group.     

Effects of static magnetic fields on cognition, vital signs, and sensory perception: a meta-analysis

To evaluate whether cognitive processes, sensory perception, and vital signs might be influenced by static magnetic fields in magnetic resonance imaging (MRI), which could pose a risk for health personnel and patients, we conducted a meta-analysis of studies that examined effects of static magnetic fields. Studies covering the time from 1992 to 2007 were selected. Cohen's d effects sizes were used and combined in different categories of neuropsychology (reaction time, visual processing, eye-hand coordination, and working memory). Additionally, effects of static magnetic fields on sensory perception and vital signs were analyzed. In the category "neuropsychology," only effects on the visual system were homogeneous, showing a statistically significant impairment as a result of exposure to static magnetic fields (d = -0.415). Vital signs were not affected and effects on sensory perceptions included an increase of dizziness and vertigo, primarily caused by movement during static magnetic field gradient exposures. The number of studies dealing with this topic is very small and the experimental set-up of some of the analyzed studies makes it difficult to accurately determine the effects of static magnetic fields by themselves, excluding nonspecific factors. The implications of these results for MRI lead to suggestions for improvement in research designs.     

Sex-related differences in frequency and perception of stressful life events during adolescence

Aim

Stressful life events and individual stress experience are important risk factors for the development of physical and mental disorders. One of the modulating factors determining interindividual differences in stress experience is the person’s gender. In the current study, we investigated sex-related differences in the frequency and perception of stressful life events during adolescence, a period characterized by particularly high stress levels.

Subject and methods

We examined 1,657 14-year-old adolescents who were recruited as part of the IMAGEN study, a European multicenter research project on mental well-being of young people. For the detection of stressful life events, we used the Life Events Questionnaire, a highly valid instrument for testing common stressful events during adolescence.

Results

Although boys and girls did not differ significantly regarding the total amount of stressful life events, girls reported more stressful events in the familial and body-related areas, whereas boys experienced more conflicts with superiors and independence-marking events. As regards valence, girls reported greater psychological distress compared to boys; however, in all significant results, the effect sizes were only small to moderate.

Conclusion

While previous research highlighted severe stressors in adult samples, we investigated for the first time adolescents with a broader scope of stressful events. The observed differences in the stress experience may contribute to explain the sex-dependent variations in the incidence of stress-related disorders.