1 Department of Psychology, Faculté des Arts et Sciences, Université de Montréal, Montréal, Canada.
2 Changping Laboratory & Peking University, Beijing, China.
3 Department of Pediatrics, Faculty of Medicine and Health Sciences, Université Sherbrooke Hospital Research Center, Sherbrooke, Canada.
4 Center for Studies in Behavioral Neurobiology and Perform Center, Department of Health, Kinesiology and Applied Physiology, Concordia University, Montréal, Canada.
5 Research Center, Institut Universitaire de Gériatrie de Montréal, Montréal, Canada.
6 Department of Psychology, Faculté des Arts et Sciences, Université de Montréal, Montréal, Canada. hugo.theoret@umontreal.ca.

Lorazepam is a fast-acting benzodiazepine that is widely used to manage anxiety symptoms through modulation of GABAergic activity. Despite being one of the most prescribed benzodiazepines, the effects of a single dose of lorazepam on brain functional connectivity at rest is not known. In this placebo-controlled, crossover study, twenty healthy adult participants (9 women; 26.2 ± 5.2 years) underwent two resting-state fMRI (rs-fMRI) scans following administration of either lorazepam (2.5 mg) or placebo. Imaging data were analyzed using an individual brain network parcellation approach and differences in functional connectivity among 78 individual-specific ROIs were estimated. Compared to placebo, functional connectivity was reduced following administration of lorazepam between the left medial paracentral lobule and left temporal pole and between the left posterior cingulate sulcus and right cuneus. Reduced connectivity within higher-order cognitive networks partly supports what has been reported for other benzodiazepines such as midazolam and alprazolam. However, differences across benzodiazepines - possibly due to pharmacokinetics, dosage and receptor selectivity - underscore the need for further research.