Circadian Influence on Prolonged Exposure Therapy for PTSD

Proposed research will examine time-of-day effects on trauma-related fear extinction using Prolonged Exposure Therapy (PE) telemedicine for Posttraumatic Stress Disorder (PTSD) in the National Center for PTSD (NCPTSD). The primary mechanistic outcome measure will be change in psychophysiological reactivity to script-driven imagery (SDI-PR) measured, in person, at pre-treatment, after 5 PE sessions (mid-treatment), and after all 10 PE sessions (post-treatment). A secondary mechanistic outcome will be session-to-session reduction in peak subjective units of distress (SUDS) ratings to imaginal exposures. The primary clinical outcome will be change in Clinican Administered PTSD Scale (CAPS-5) severity score; a secondary clinical outcome will be session-to-session reduction in self-reported PTSD symptoms using the PTSD checklist (PCL-5). Participants meeting inclusion criteria (described below) will be randomized to either PE sessions that begin from 07:00 to a time no later than 2 hours past a participant's customary rise time, or to the last treatment session of the day beginning at 16:00 or later (26 per arm). Participants will complete daily at-home imaginal-exposure homework within the same time frame as their PE sessions are scheduled, i.e., within 2 hours of awakening for morning (AM) group and between 16:00 and 2 hours before bedtime for late afternoon (PM) group.

Proposed research will examine time-of-day effects on trauma-related fear extinction using PE therapy for PTSD in the National Center for PTSD (NCPTSD). The primary mechanistic outcome measure will be change in SDI-PR; a secondary mechanistic outcome will be session-to-session reduction in peak SUDS ratings to imaginal exposures. The primary clinical outcome will be change in CAPS-5 severity score; a secondary clinical outcome will be session-to-session reduction in self-reported PTSD symptoms (PCL-5). Participants meeting inclusion criteria (described below) will be randomized to either PE sessions that begin from 07:00 to a time no later than 2 hours past a participant's customary rise time, or to the last treatment session of the day beginning at 16:00 or later. Participants will complete daily at-home imaginal-exposure homework within the same time frame as their PE sessions are scheduled (i.e., within 2 hours of awakening for morning group and between 16:00 and 2 hours before bedtime for late afternoon group). The assessment schedule will be identical for all participants. Participants who meet study inclusion criteria at screening will first begin a 7-day, pre-study sleep-monitoring period with wrist actigraphy, sleep diaries and completion of a diurnal profile of salivary cortisol levels. Trauma-related fear will be assessed using the standard SDI procedures detailed below at pre-treatment, after 5 PE sessions (mid-treatment), and after all 10 PE sessions (post-treatment). The CAPS-5 will be administered at these same times. PCL-5 measurements will be obtained at each treatment session and SUDs will be obtained during all treatment sessions that include imaginal exposure (sessions 3-8). All SDI sessions will be carried out at a standardized time of day in the late-afternoon (15:00-17:00). PE treatment will be administered at a targeted rate of once per week. At each PE and assessment session, pre-session saliva samples will be obtained for cortisol measurement and normalized using the diurnal profile of cortisol obtained during the sleep-assessment week. Participants will wear the wrist actigraph and complete sleep diaries throughout PE. The diurnal cortisol profile will be repeated at the post-treatment assessment.