Somatic Symptom Disorder (DSM-5)

The main objective of this randomized clinical trial is to study if various modalities of brief (eight sessions) and ultra-brief (four sessions) transdiagnostic cognitive-behavioral treatment work for decrease emotional symptoms and disorders, as well as to find out which emotional regulation processes and common factor of the intervention itself are involved in the therapeutic improvement. The investigators will compare the interventions of four groups: ultra-brief group treatment (1), brief group treatment (2), ultra-brief individual treatment (3) with the ultra-brief relaxation (control) group. The main questions the study aims to answer are: * Will the brief and ultra-brief treatment formats works better than the relaxation-based control group? * Will results obtained between the brief group therapy group and the ultra-brief group therapy group be similar? * Will the individual ultra brief therapy be more effective than the two group therapies because of common factors, such as the therapeutic alliance? * Will group therapies be more beneficial for cost and in terms of capability to reduce emocional symptoms than individual therapy? Participants will be randomly assigned to each of the groups and will receive the corresponding treatment, with different number of sessions. They will answer a series of questionnaires at the beginning and at the end of the intervention, as well as 3 months and 6 months after the end of the treatment.

This single-center, randomized, double-blind, placebo-controlled trial evaluates the efficacy and safety of fluoxetine (40 mg/day) versus placebo in 194 adults with refractory chronic constipation exhibiting Somatic Symptom Disorder (SSD) features diagnosed by SCID-5. After a 2-week screening period, participants are randomized 1:1 to fluoxetine or matching placebo for 12 weeks. The primary endpoint is the proportion of CSBM responders, defined as an increase of ≥1 CSBM per week from baseline in ≥50% of treatment weeks (Weeks 5-12). Key secondary endpoints include weekly SBM/CSBM frequency, Bristol Stool Form Scale, straining score, bloating severity, Patient Global Impression of Change (PGIC, 7-point), and changes in validated PRO scales (SSD-12, PHQ-15, PHQ-9, GAD-7, PAC-QOL, KESS). Mechanistic assessments include resting-state fMRI and high-resolution anorectal manometry (HRAM). Safety is monitored through adverse events, thyroid/liver/renal function tests, and ECG.

Persistent somatic symptoms significantly impair the daily lives of individuals with Somatic Symptom Disorder (SSD). Negative psychological factors (NPFs), such as catastrophizing and negative affectivity, further compound this impairment. Yet, few studies have examined strategies in daily life that directly target somatic symptoms and their dynamic relationship with NPFs. The goal of this clinical trial is to investigate if an Ecological Momentary Intervention (EMI) using music listening and cognitive reappraisal can reduce the intensity of and impairment due to somatic symptoms in 40 individuals with Somatic Symptom Disorder (SSD), aged 18-65 years. Participants will report symptom intensity, impairment, and NPFs up to four times daily via a smartphone app over a six-week period. Using an intraindividual randomized controlled design, during weeks two to five, participants will be randomly assigned in the ratio of 50:25:25 to no intervention, music listening, and cognitive reappraisal, both at fixed times (evening measurement) and during episodes of acute somatic impairment.

The purpose of this randomized, double-blind, placebo-controlled trial is to evaluate the efficacy and safety of transcranial alternating current stimulation (tACS) in adults with refractory functional constipation comorbid with somatic symptom disorder. This population is characterized by persistent bowel dysfunction despite conventional treatments, frequent reliance on laxatives, and evidence of impaired brain-gut regulation contributing to chronic symptoms. The study focuses on three primary domains: Efficacy - Bowel Function: • Assessment of whether a 4-week course of tACS improves bowel activity, measured by changes in Complete Spontaneous Bowel Movements (CSBM) and overall bowel-movement frequency over the treatment and follow-up period. Efficacy - Symptom and Quality of Life Burden: • Evaluation of the effect of tACS on constipation-related severity and patient-reported outcomes, including the Patient Assessment of Constipation-Symptoms (PAC-SYM) and Patient Assessment of Constipation-Quality of Life (PAC-QOL). Safety and Tolerability: • Documentation of adverse events associated with tACS, with particular attention to incidence, intensity, and overall patient tolerability compared with sham stimulation.