Mismatch vs. Standard Intervention During Memory Reconsolidation Blockade With Propranolol: Effect on Psychophysiological Reactivity During Traumatic Imagery

Inclusion Criteria: * Initial participants will be males or females 18-65 years old who have experienced a traumatic event that meets the DSM-5 PTSD A criterion, and whose PCL-5 score is \>33 (to maximize the likelihood that they will meet our psychophysiological inclusion criterion). In order to be randomized, participants must further meet this psychophysiological inclusion criterion during baseline script-driven imagery testing Although we do not require a diagnosis of PTSD, because we have set a minimum psychophysiological inclusion criterion and a valid Criterion A traumatic event, our sample will include a substantial number, likely a majority, of PTSD participants. Exclusion Criteria: 1. Basal sitting or standing systolic blood pressure \<90/60 mm Hg or basal HR \<50 BPM. Those participant-candidates excluded for this reason with such readings will be counseled and referred for further clinical consultation if symptomatic or if they wish to be referred even if asymptomatic. 2. Medical condition that contraindicates PPNL, e.g., congestive heart failure, heart block, insulin- requiring diabetes, chronic bronchitis, emphysema, or asthma. Asthma attacks will only be exclusionary if they: a) occurred within the past ten years, b) occurred at any time in life if induced by a β-blocker, or c) are currently being treated 3. Previous adverse reaction to, or non-compliance with, a β-blocker 4. Current use of medication that may involve potentially dangerous or confounding interactions with PPNL, including anti- hypertensives, antiarrhythmics, and benzodiazepines. (Possible inhibition of CYP2D6 isoenzyme-dependent reactions will not be of concern in this study, because PPNL will only be administered once a week) 5. Presence of drugs of abuse, including opiates, marijuana, cocaine, amphetamines, or alcohol at the initial assessment 6. Pregnancy or breast feeding. Women of childbearing potential will have a pregnancy test at the initial assessment 7. Presence of a contraindicating psychiatric condition, e.g., psychotic, bipolar, melancholic, or active substance use disorder; or suicidality (see below) 8. Initiation of, or change in, psychotropic medication within the previous two months. For participants receiving stable doses of pharmacotherapy, they and their clinicians-prescribers will be asked not to alter the regimen during the proposed two-month study period (excluding the one-month follow-up) except in clinically urgent circumstances. If this becomes necessary, a decision will be made on a case-by-case basis about retaining the participant or terminating participation 9. Current participation in any psychotherapy other than supportive. Participants will be asked not to initiate new psychotherapy during the proposed two-month study period (excluding the one-month follow-up) except in clinically urgent circumstances. If this becomes necessary, a decision will be made on a case-by-case basis about retaining the participant or terminating participation 10. Inability to understand the study's procedures, risks, and side effects, or to otherwise give informed consent for participation 11. Participant candidate does not understand English. This exclusion criterion is necessary because the procedures require a nuanced dialogue with English-speaking investigators.