Dissociable effects of LSD and MDMA on striato-cortical connectivity in healthy subjects.

LSD and MDMA, two psychoactive drugs being explored for psychiatric use, alter how the striatum—a brain region involved in reward and motivation—communicates with other areas. Using resting-state fMRI data from prior studies, researchers examined striatal connectivity after acute drug administration. Neither drug changed connectivity within the striatum's own networks. However, MDMA reduced connections between the limbic striatum and the amygdala, while LSD increased connections between the associative striatum and frontal, sensorimotor, and visual cortices. These changes occurred mostly outside standard striatal networks, supporting the idea that psychedelics reduce the brain's usual network segregation, potentially explaining their therapeutic and psychological effects.

Study at a glance

Abstract

Lysergic acid diethylamide (LSD) and 3,4-Methylenedioxymethamphetamine (MDMA) are widely used psychoactive drugs and their potential use in psychiatric medicine is currently generating interest. The mechanism by which these drugs may assist recovery in various disorders such as addiction and post-traumatic stress disorder (PTSD) is still not well understood. Most investigations of the effects of these drugs on brain activity have focused on cortical resting-state networks, however the striatum is a key reward and motivation hub of the brain and aberrant striatal processing may be part of the pathophysiology of these disorders. Consequently, we investigated striatal connectivity following acute MDMA and LSD administration. Resting-state fMRI (rs-fMRI) data were acquired from two separate previous studies, and seed-voxel functional connectivity analyses were used with the striatum subdivided into three seed regions: the associative, limbic, and sensorimotor striatum. Within-network connectivity was measured using group mean network maps and whole-brain connectivity (seed-to-voxel) was also examined. Neither MDMA nor LSD significantly changed within-network connectivity of any of the three striatal seed regions. However, striatal connectivity with other brain regions was significantly altered with both MDMA and LSD. Most notably, MDMA reduced connectivity between the limbic striatum and the amygdala, while LSD increased connectivity between the associative striatum and the frontal, sensorimotor, and visual cortices. Changes in connectivity were mostly observed outside the standard striatal networks, consistent with previous findings that psychedelics reduce network modularity or between-network segregation and increase connectivity across standard networks.