The investigators intend to utilize state-of-the-art validated Human Connectome Project (HCP) style approaches to determine the effects of MDMA on prefrontal and amygdala activation, and to explore the relationship between these MDMA-induced neural changes and the acute behavioral effects of the drug in patients with PTSD. In addition, the investigators will collect preliminary data on the MDMA effects on large-scale intrinsic functional connectivity using novel graph-based network analyses.~Specifically, the investigators will measure medial prefrontal cortex (mPFC) and amygdala activation in response to negative stimuli in patients with PTSD. The investigators hypothesize that MDMA will increase mPFC, but decrease amygdala, activation in response to negative stimuli.~The investigators will also explore the relationship between the MDMA-induced mPFC and amygdala activation, and performance on Ekman's Emotional Facial Expression task. This task is modulated by the mPFC and amygdala and as well as trauma severity in participants with PTSD. And finally, to explore the effects of MDMA on resting-state functional connectivity (rs-fcMRI) the investigators will use Coupled Intrinsic Connectivity Distribution (Coupled-ICD); an innovative, graph-based, fully data-driven approach that is particularly sensitive to paired rs-fcMRI data (e.g. pre/post-treatment).~Adult participants with PTSD will be recruited for a double-blind, placebo-controlled, within-subjects, crossover-dose neuroimaging study in which they will initially receive either a single dose of MDMA 1.5mg/kg or a placebo (niacin 250mg), with a crossover dose to follow. Doses will be separated by 2 weeks.
This study aims to investigate the effects of MDMA on prefrontal and amygdala activation, and to explore the relationship between these MDMA-induced neural changes and the acute behavioral effects of the drug in patients with PTSD.