Emotion Regulation-based Internet-delivered Cognitive Behavioural Therapy for Premenstrual Dysphoric Disorder

Premenstrual dysphoric disorder (PMDD) is a debilitating cyclic mental disorder affecting about 2-5% of women of reproductive age. PMDD is characterised by recurring emotional, behavioural, cognitive, and somatic symptoms that arise during the luteal (premenstrual) phase of the menstrual cycle and remit shortly after the onset of menses. Although pharmacological interventions are available, many women experience residual symptoms, discontinue treatment or refrain from them because of side effects. Therefore, non-pharmacological treatment options are needed.

Preliminary evidence suggests that internet-delivered cognitive behavioural therapy (ICBT) is a promising candidate, but further research is warranted. Also, there is room for treatment improvement. Specifically, it has been suggested that components targeting emotional and interpersonal dysregulation should be incorporated into CBT for PMDD. The current study aims to assess the effects of an ICBT intervention for PMDD incorporating skills training in emotion regulation and interpersonal effectiveness in a randomised controlled trial (RCT).

The study is a parallel two-group RCT with 1:1 allocation to 8 weeks of a therapist-guided self-help ICBT for PMDD or a waitlist control group. Approximately 164 women (age 18-45) fulfilling the DSM-5 diagnostic criteria for PMDD will be randomly assigned.

Recruitment

Participants will be recruited from the general population using the following screening procedure.

1. Web-based screening for PMDD (Premenstrual Screening Tool) and other eligibility criteria
2. Clinical diagnostic (telephone) interview assessing preliminary PMDD diagnosis and psychiatric comorbidity
3. Prospective daily ratings of premenstrual symptoms during two consecutive menstrual cycles using the Daily Report of Severity of Problems (DRSP).

Outcomes and Expected Results

Primary outcomes are pre- to post-treatment group differences in premenstrual symptoms and their impact on everyday life (prospective daily ratings, two menstrual cycles pre- and post-treatment) and PMDD-related psychological and functional impairment (retrospective ratings). Participants in the treatment group (vs waiting list) are expected to report a reduction in primary outcomes during the luteal (premenstrual) phase after treatment (vs baseline). No group differences in outcomes are expected during the follicular (post-menstrual) phase.

Secondary outcomes include treatment effects on quality of life (QoL) and difficulties in emotion regulation. Participants in the treatment group are expected to report higher QoL and lower levels of difficulties in emotion regulation after treatment (vs. baseline) than the waitlist control group. To assess long-term treatment effects, follow-up assessments will be conducted 6 and 12 months after treatment.

Health economic data will be collected for future health economic evaluations of the treatment.

Analysis

All randomised participants will be included in the intention-to-treat (ITT) population, regardless of whether they received or completed treatment. The per-protocol (PP) population will be a subgroup of the ITT population containing all participants without a major protocol violation. Sensitivity analyses will also be conducted with (1) participants who have completed at least four mandatory modules (modules 1-4) and (2) participants who have completed at least four mandatory modules and at least one of the optional lifestyle modules. To further explore potential differential effects of ICBT, exploratory analyses will be conducted for different symptom clusters (e.g., affective symptoms) and symptom trajectories in terms of onset and/or in combination with severity and severity peak. The relationship between difficulties in emotion regulation and improvement in primary outcomes will also be explored.

Eligibility Criteria:
Inclusion Criteria:

1. PMDD diagnosis according to DSM-5
2. Menstrual cycle length between 23-34 days, i.e., 5-8 cycles in the last six months
3. Sufficient proficiency in Swedish to comprehend the treatment materials
4. Access to computer/tablet/mobile phone with internet connection

Exclusion Criteria:

1. Breastfeeding or pregnancy during the previous three months
2. Initiation of or change in treatment with antidepressants, benzodiazepines, contraceptives, or hormones during the last three months
3. Current or history of a gynaecological disease (e.g., endometriosis, polycystic ovary syndrome) that may confound the results
4. Ongoing or previous psychological treatment for premenstrual disorders
5. Severe mental disorders that may interfere with the person's ability to complete the treatment or complicate the interpretation of results, e.g., psychosis, bipolar disorder, severe eating disorder, or severe depression
6. Elevated suicide risk (e.g., recurrent active suicidal ideation, current suicide plans, previous suicide attempts).