Abstract
Background and purpose: In clinical practice, lorazepam is commonly prescribed to reduce anxiety. Functional MRI studies have demonstrated reduced cerebral activation in the emotional circuit by the anti-anxiety effect on decision-making and facial affective processing. However, to our knowledge, the effect on functional connectivity in affective processing by anti-anxiety drug has not been fully investigated. We investigated the effect of the anti-anxiety drug lorazepam and a placebo on cerebral functional connectivity during listening to affective vocalizations.
Methods: Twenty-four right-handed subjects participated in this study. After acquiring informed consent, each subject participated in a randomized controlled trial for 3 days. The subjects were scanned by functional MRI (fMRI) at non-drug, placebo, and lorazepam. They took the drug/placebo 2 hours before fMRI. Subjects performed judgement of emotional valence (positive, negative, neutral) to selected vocal sets from Montreal Affective Voices during fMRI. We analyzed functional connectivity while subjects listened to fearful vocalizations under 3 conditions: non-drug, placebo, and 1mg lorazepam. In this study, we compared functional connectivity among the 3 conditions.
Results: Compared with non-drug, the conditions of placebo and lorazepam showed significantly decreasing functional connectivity in the anterior-middle cingulate and left-right primary visual cortex (p<0.05). Compared with non-drug and lorazepam, the condition of placebo showed significantly increased functional connectivity between inferior temporal gyrus (ITG) and inferior parietal lobe (IPL) (p<0.05). Compared with non-drug and placebo, the condition of lorazepam showed significant decrease of functional connectivity between left precentral gyrus and left middle cingulate (p<0.05).
Conclusions: Our findings demonstrated that cerebral functional connectivity by affective processing was susceptible by anti-anxiety drug. Especially, these were suggested: 1) decreasing connectivity in anterior cingulate and primary visual cortex by anti-anxiety effect, 2) increasing left tempo-right parietal connection by placebo effect, and 3) decreasing left precentral-cingulate connectivity by lorazepam.