Effects of overnight fasting on working memory-related brain network: an fMRI study.

Glucose metabolism serves as the central source of energy for the human brain. Little is known about the effects of blood glucose level (BGL) on higher-order cognitive functions within a physiological range (e.g., after overnight fasting). In this randomized, placebo-controlled, double blind study, we assessed the impact of overnight fasting (14 h) on brain activation during a working memory task. We sought to mimic BGLs that occur naturally in healthy humans after overnight fasting. After standardized periods of food restriction, 40 (20 male) healthy participants were randomly assigned to receive either glucagon to balance the BGL or placebo (NaCl). A parametric fMRI paradigm, including 2-back and 0-back tasks, was used. Subclinically low BGL following overnight fasting was found to be linked to reduced involvement of the bilateral dorsal midline thalamus and the bilateral basal ganglia, suggesting high sensitivity of those regions to minimal changes in BGLs. Our results indicate that overnight fasting leads to physiologically low levels of glucose, impacting brain activation during working memory tasks even when there are no differences in cognitive performance.

Electroconvulsive therapy as viewed by german psychiatrists: a comparison of 3 subgroups.

OBJECTIVES: Electroconvulsive therapy (ECT) is a stigmatized treatment even among doctors. This restrains the accessibility of ECT for patients in need of this treatment. In Germany, the utilization of ECT is low as compared with other Western industrialized countries. However, increasing application rates of ECT in Germany indicate some degree of support from psychiatrists. Therefore, the present study examined the current attitudes among 3 subgroups of psychiatrists toward ECT. METHODS: A questionnaire was sent through e-mail to 423 psychiatric hospitals in the Federal Republic of Germany and through facsimile to 2550 specialists working in private practice. One hundred eighty-three (43%) of the institutions applied ECT (ECT facilities) and 240 (57%) institutions did not apply (non-ECT facilities). RESULTS: Nine hundred eighty-three answers could be evaluated. One hundred fifteen (63%) of the 183 ECT facilities, 118 (49%) of the 240 non-ECT facilities, and 751 (30%) of the 2500 specialists working in private practice responded. The general attitude toward ECT was favorable: most of the participants agreed that ECT is used less often than it should be to best serve patients' interests (61%-89%) and that it should be applied more often (54%-79%). Most of the participants thought that the image of ECT has improved among psychiatrists (61%-74%) but has not changed among fellow physicians, patients, and the general population. CONCLUSIONS: A surprisingly positive attitude toward ECT was found in our study among all 3 groups of German psychiatrists, which might further help improve patients' access to this treatment.

Investigating the impact of overnight fasting on intrinsic functional connectivity: a double-blind fMRI study.

The human brain depends mainly on glucose supply from circulating blood as an energy substrate for its metabolism. Most of the energy produced by glucose catabolism in the brain is used to support intrinsic communication purposes in the absence of goal-directed activity. This intrinsic brain function can be detected with fMRI as synchronized fluctuations of the BOLD signal forming functional networks. Here, we report results from a double-blind, placebo controlled, cross-over study addressing changes in intrinsic brain activity in the context of very low, yet physiological, blood glucose levels after overnight fasting. Comparison of four major resting state networks in a fasting state and a state of elevated blood glucose levels after glucagon infusion revealed altered patterns of functional connectivity only in a small region of the posterior default mode network, while the rest of the networks appeared unaffected. Furthermore, low blood glucose was associated with changes in the right frontoparietal network after cognitive effort. Our results suggest that fasting has only limited impact on intrinsic brain activity, while a detrimental impact on a network related to attention is only observable following cognitive effort, which is in line with ego depletion and its reliance on glucose.

Hemodynamic effects of exogenous adrenomedullin in healthy and endotoxemic sheep.

Adrenomedullin (AM) is a vasodilatory peptide hormone, playing a key role in the regulation of cardiovascular homeostasis. In view of the circulatory failure in sepsis, it is still debated as to whether the occurrence of vascular hyporeactivity against AM plays a causative or protective role. This study was designed as a prospective, controlled trial to elucidate the hemodynamic response following a titrating infusion of human AM in healthy and endotoxemic sheep. ANOVA demonstrated that AM infusion produced hypotension and tachycardia, and increased cardiac index in a dose-dependent manner, both in healthy and endotoxemic sheep. In addition, AM application reduced pulmonary vascular resistance index in ovine endotoxemia (P=0.02). These findings confirm that AM produces a hyperdynamic circulation, in the presence and absence of systemic inflammation. Further, exogenous AM could possibly be a useful adjunct in the common setting of sepsis-associated pulmonary hypertension.