Posttraumatic stress disorder (PTSD) is a multifaceted disorder resulting from intense and/or life-threatening trauma. PTSD sequelae often have a ripple effect on close others, including spouses and children. Studies report high levels of relationship distress for both those with PTSD and their partners as well as emotional distress. Despite the extensive knowledge on the effects of PTSD on couple relations and vice versa, and the limitations of individual therapies in addressing these issues, there has been a major lag in the development and study of couples' interventions in the context of PTSD. the current study will examine the efficacy of Cognitive Behavioral Conjoint Therapy (CBCT) for PTSD. It will employ an RCT to examine both outcomes and processes of change via multiple methods of assessment, including self-report questionnaires, qualitative interviews and physiological co-regulation measures. Moreover, it will employ a modified procedure via video conference due to COVID-19 in addition to in-person treatment option. The study will therefore contribute to theoretical understandings of the effects of PTSD on couples, to the development of therapies specifically intended for such couples.

Posttraumatic stress disorder (PTSD) is a multifaceted disorder resulting from intense and/or life-threatening trauma. PTSD sequelae often have a ripple effect on close others, including spouses and children. Despite the extensive knowledge on the effects of PTSD on couple relations and vice versa, and the limitations of individual therapies in addressing these issues, there has been a major lag in the development and study of couples' interventions in the context of PTSD.

The current study will examine the efficacy of Cognitive Behavioral Conjoint Therapy (CBCT) for PTSD. It will employ RCT design to examine both outcomes and processes of change via multiple methods of assessment, including self-report questionnaires, qualitative interviews, and physiological co-regulation measures. Moreover, it will employ a modified procedure via video conference due to COVID-19.

The first aim is to examine the efficacy of CBCT using multiple methods in RCT design in the Israeli context. The following hypotheses related to treatment efficacy will be examined:

1. The investigators expect that the CBCT group will show a larger decrease in the level of patient PTSS and a decrease in depression, anxiety, anger, guilt and marital aggression among both partners in comparison to the waiting list (WL) controls. Marital satisfaction of both partners is expected to increase.
2. The investigators expect that each of the spouses will gradually, over the course of treatment, show more regulated autonomic nervous system (ANS) activity (e.g., GSR, HRV, RSA) among the CBCT group; The investigators also expect more positive physiological co-regulation between spouses over time.

2. The second aim of the study is to understand change processes and mechanisms specific to CBCT. The following hypotheses will be examined:

1. The investigators will examine the mediating role of accommodation, emotional regulation, self-disclosure and partner responsiveness: compared to WL controls, CBCT will be associated with higher levels of these factors in mid-treatment, and they in turn will be associated with better outcomes (e.g., PTSS, depression, marital adjustment) post-treatment.
2. The investigators expect that synchrony levels between the couples will rise after CBCT. In addition, (2.a) The investigators expect PTSD severity and marital satisfaction to moderate these associations: Among couples where the individual with PTSD has more severe PTSD and where couples report on lower levels of marital satisfaction, the change in the level of arousal and strength of physiological synchrony will be lower.
3. The investigators expect that synchrony levels between the couples will rise from session to session. The investigators will also explore the dynamics of change in physiological co-regulation during sessions, as they correspond with different components of the intervention protocol. In addition The investigators will explore the association between synchronicity to the study's main outcomes (e.g., PTSS, depression, marital adjustment) post-treatment.

(3.b) The investigators will examine the role of accommodation as a mediator of change in the level of physiological co-regulation before and after the intervention. Thus, compared to WL controls, those in CBCT will show more accommodation over time, which in turn will be associated with higher levels of synchrony/co-regulation.

As for the qualitative design, it does not assume hypotheses, but rather poses questions. A sub-sample of 15 couples will undergo a semi-structured qualitative interview regarding their subjective experience in therapy, before and after the intervention. The interview will consist of pre-defined open-ended questions regarding 4 main elements: 1. The expectations and the experience of couples' therapy via video conference. 2. Assessing the impact and effectiveness of the intervention on couples relationship and psychological distress; 3. Changes that occurred in spouses' mutual understanding of PTSD, its effects on the relationship, and how they handle and react in light of these effects. This will give participants a chance to describe their experiences over the course of therapy in their own words. In this part of the study, there is one directional hypothesis: The investigators expect interviews to reflect a positive experience from therapy, reflecting both symptomatic change (in PTSS) and positive changes in couples' adjustment and relationship.

The study is a randomized controlled trial (RCT), including 60 couples (120 participants in total) in which one of the spouses suffers from PTSD. An initial phone prescreen will be conducted to determine possible eligibility for all potential participants who respond or are referred via various recruitment strategies. The phone prescreen will be used to provide initial information about the study and the assessment procedures, as well as initial Screening method to assess level of motivation and relationship status. Individuals who appear eligible will then be contacted for two longer screening sessions with a trained staff member, via video conference, to further assess eligibility based on the exclusion criteria. During the screening sessions, participants will be sent an electronic consent form. Participants will be asked to complete an online survey collecting demographic information, self-report questionnaires and the Clinicians Administered PTSD Scale for DSM-V. The self report questionnaires will assess: (a) active psychosis; (b) substance use; (c) suicidal risk; (d) physical, verbal or cyber aggression in the relationship. Participants data will be collected through Qualtrics, an online data-capture tool. Participants excluded for significant suicidal ideation, psychosis or substance abuse will be referred to appropriate treatment options. Couples found to be eligible will receive a thorough explanation about the treatment, the study and its various components, and will subsequently be randomized using a block randomization method for assignment.

The couples will be randomly assigned to 2 conditions: (1) Group CBCT (n=30), (2) Waitlist control group, subsequently assigned to treatment (n=30). The CBCT intervention will be conducted remotely through video conference. As the study continues, participants may be given the option to choose between remote therapy and face-to-face meetings, depending on the state of COVID-19 spread in Israel. Participants will complete structured clinical interview and self-report questionnaires tapping psychological (PTSD symptoms, depression, anger), behavioral (domestic violence), and marital satisfaction; As well as physiological measures (HRV and skin conductance) at 4 assessments: pre-/during/post- treatment, and 4 months after treatment.

To date, no RCT has examined CBCT for PTSD in Israel or examined the treatments efficacy when sessions take place in a telehealth platform. In addition, The study will be the first study to examine physiological co-regulation changes due to CBCT for PTSD. Therefore, the study will contribute to theoretical understandings of the effects of PTSD on couples, to the development of therapies specifically intended for such couples. and finally, to the well-being of Israeli PTSD patients and their spouses.

Inclusion Criteria:

1. have a cohabiting partner or spouse and both spouses must commit to staying in the relationship through 15 sessions of CBCT for PTSD
2. have a current diagnosis of PTSD based on Diagnostic and Statistical Manual of Mental Disorders (5th Edition [DSM-5]; [2]), assessed with the Clinician Administered PTSD Scale for DSM-5 (CAPS-5;80)
3. not participate in concurrent psychotherapies directly targeting PTSD (e.g., eye movement desensitization and reprocessing; present centered therapy; PE) or concurrent couples therapy

Exclusion Criteria:

1. unmanaged active psychosis or manic episode (assessed with Yale University PRIME Screening Test)
2. substance use disorder warranting primary substance use treatment or detoxification (assessed with AUDIT;109 and DAST-10;110])
3. Imminent suicidal risk (assessed with Paykel questionnaire;111)
4. severe physical, verbal or cyber aggression currently or in the past 3 months (assessed with CARS;112 and CTS-2;84)
5. a current PTSD diagnosis for both spouses (assessed with CAPS-5;80).

IPD would be available to other researchers, including Study Protocol, Statistical Analysis Plan, Informed Consent Form, Clinical Study Report and Analytic Code through e- mail or publications.

Participant, therapists, investigators and outcome assesors are blind to the condition the individual participant was assigned to, by encrypting the names of the individual into a number-letter codes.The therapists led the intervention group was not aware of the participants condition.