Leveraging veterans' intimate relationships during treatment for posttraumatic stress disorder (PTSD) has the potential to concurrently improve PTSD symptoms and relationship quality. Brief Cognitive-Behavioral Conjoint Therapy (bCBCT) is a manualized treatment designed to simultaneously improve PTSD and relationship functioning for couples in which one partner has PTSD. Although efficacious in improving PTSD, the effects of CBCT on relationship satisfaction are small, especially among Veterans. Pharmacological augmentation of bCBCT with intranasal oxytocin, a neurohormone that influences mechanisms of trauma recovery and social behavior, may help improve the efficacy of bCBCT. The purpose of this randomized placebo-controlled trial is to compare the clinical and functional outcomes of bCBCT augmented with intranasal oxytocin (bCBCT + OT) versus bCBCT plus placebo (bCBCT + PL). The investigators will also explore potential mechanisms of action: communication, empathy, and trust.

The primary aim of this study is to investigate the effects of Brief Cognitive Behavioral Conjoint Therapy (bCBCT) paired with intranasal oxytocin (OT) versus placebo on PTSD symptoms, intimate relationship satisfaction and psychosocial functioning in a sample of veterans with PTSD (across all measures) and their intimate partners (relationship satisfaction only). The study will also explore the impact of intranasal oxytocin on potential mechanisms of action (i.e., communication skills, empathy, and trust).

bCBCT is a modified PTSD-specific cognitive-behavioral psychotherapy attended by the couple that uses close relationships as the vehicle for recovery. Across eight 75-minute sessions, this manualized therapy addresses the patient's PTSD and relationship functioning simultaneously via its focus on PTSD psychoeducation within relationship contexts, communication skills, behavioral approach exercises, and cognitive interventions.

Oxytocin is a 9-amino-acid nonapeptide hormone produced by the paraventricular and supraoptic nuclei of the hypothalamus that regulates human emotions, social cognition, and social behaviors. Oxytocin is released to several brain areas, including the amygdala, hypothalamus, hippocampus, insula, and striatum, and effects are mediated by oxytocin receptors found in these regions.

Intranasal administration of oxytocin may offer understanding of the causal effects of oxytocin on human behavior. Intranasal oxytocin is safe and easy to administer, with a short half-life that makes it highly suitable for adding to behavioral interventions. Intranasal oxytocin is best known for its widespread effects on affiliative processes and behaviors. For example, intranasal oxytocin increases trust, empathy, generosity, positive communication, and emotional disclosure. Oxytocin also improves social cognition, including emotion recognition and empathic accuracy. The combination of intranasal oxytocin with provision of social support suppresses cortisol release and subjective responses to social stress.

Intranasal oxytocin can be conceptualized as a "psychotherapy process catalyst", in that oxytocin could enhance patients' openness to intervention, attention to others' communication, and willingness and ability to develop therapeutic alliance. A recent systematic review of 14 studies of the effects of intranasal oxytocin on PTSD symptoms concluded that there is tentative evidence for the clinical utility of intranasal oxytocin for PTSD, although more studies with chronic administration among clinical samples are needed.

The investigators will employ a double blind, placebo-controlled RCT design in which Veterans will receive a dose of oxytocin or placebo before each bCBCT session and complete mid-treatment, post-treatment, 3-month, and 6-month follow-up assessments. Based on the findings from past bCBCT trial and the investigators' recent bCBCT + OT pilot study, the investigators anticipate about 1/3 of the sample will be dual Veterans or the identified Veteran is female. The investigators project an approximate 20-25% attrition rate, resulting in approximately 100 couples completing treatment. Consistent with past trials, to enhance retention, the investigators will ask couples to provide contact information for collateral informants who can reach them if the investigators are unable to do so via their primary contact information. Study personnel will routinely remind couples of appointments via telephone and/or letters and the team will meet weekly to review and problem-solve retention strategies. These are all established procedures implemented from successful prior trials. If successful, the study will advance knowledge of strategies for improving Veterans' quality of life by improving their intimate relationships along with PTSD symptoms.

Inclusion Criteria:

Inclusion criteria for Veteran:

1. Be a Veteran (age 18 or older) with a current DSM-5 diagnosis of PTSD (as assessed by the CAPS-5 with a minimum severity score of 25) no less than 3 months after the index trauma occurred (to allow for potential natural recovery)

2. Be on a stable psychoactive medication regimen for at least 4 weeks (if applicable)

3. Be enrolled and eligible to receive care at the VASDHS

   Inclusion criteria for Partner:

4. Be an intimate partner (age 18 or older) who is willing to participate in the intervention (partners can also be Veterans but cannot meet criteria for possible PTSD per the PCL-5)

   Inclusion criteria for Veteran and Partner:

5. Be married, or cohabitating for at least 6 months

6. Willing to be randomized into either treatment condition (bCBCT + OT or bCBCT + PL)

7. Agree to have assessment and treatment sessions audio/video recorded

8. Agree not to receive other individual trauma-focused psychotherapy for PTSD or any form of conjoint therapy during the treatment portion of the study

9. Have the capacity to participate in virtual care (access to internet via DSL or a cable provider, private space)

   Exclusion Criteria:

   Exclusion criteria for Veteran and Partner:

10. Current substance dependence in either member of the couple not in remission for at least 3 months, as assessed by the Alcohol Use Disorders Identification Test (AUDIT)74 and Drug Abuse Screening Test (DAST)75

11. Any current uncontrolled psychotic disorder in either member of the couple as assessed by positive screen on the Prime Screen-Revised (PS-R). Exclusion to be determined following case consult by PI or other clinician.

12. Imminent suicidality or homicidality in either member of the couple (e.g., C-SSRS)

13. Any severe cognitive or medical impairment in either member of the couple making it difficult to regularly attend weekly couples psychotherapy

14. Any perpetration of severe physical or sexual relationship aggression (as assessed by the CTS-2) or fear/intimidation (3-item IPV screen, Couples Questionnaire) in the past year

    Exclusion criteria for Veteran:

15. Severe ongoing medical problems, including heart disease, uncontrolled hypotension (systolic blood pressure <100 mm Hg) or hypertension (systolic BP >130 or diastolic BP > 80 mm Hg), and neuroendocrinological disorders (e.g., diabetes). Exclusion to be determined in collaboration with study physician following completion of physician's one-on-one appointment with Veteran and review of all relevant information (e.g., risk factors, health history, concomitant medications, etc.) from Veteran's VA medical record and study screening/assessment processes including selfreport measures and blood pressure measurement. Additionally, Veterans for whom the study physician has elevated concern, will be asked to attend an in-person visit at a VA medical center, clinic, or the Veterans Medical Research Foundation before enrollment.

16. Positive screen (7+) for borderline personality disorder (BPD) as assessed by the MacLean Screening Instrument for BPD76. Exclusion to be determined following case consult by PI or other clinician.

17. Pregnancy, delivery in the past 6 months, current breastfeeding, or the ability to become pregnant while not practicing an effective method of contraception. If able to become pregnant, Veteran must have a highly sensitive negative urine pregnancy test verified visually via telehealth or in-person at the Veterans Medical Research Foundation by research staff at study entry and prior to each medication administration during treatment. Veteran must verbally confirm that they completed the test themselves that day. Veteran must also agree to use an effective birth control method from study entry until conclusion of treatment to prevent pregnancy. The ability to become pregnant is defined as: assigned female at birth, fertile, following menarche and until becoming post-menopausal unless permanently sterile. Permanent sterilization methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy.

    Effective birth control methods include intrauterine device (IUD), injected, implanted, intravaginal, or transdermal hormonal methods, oral hormones, a barrier contraception method (e.g., male or female condoms, diaphragm, cap), or vasectomized sole sexual partner.

    Pregnancy tests will be purchased by the study and mailed to Veteran unless PI has approved waiver of testing requirement.

18. Known allergy to preservatives (i.e., Methylparaben, Propylparaben, Glycerin, Sodium Benzoate, Potassium Sorbate, and Disodium EDTA) utilized in oxytocin nasal spray.

Double-blind, quadruple masking