Is psychotherapy delivered in videoconference as effective as in face to face for GAD?

INTERVENTION: After receiving an appropriate diagnosis and completing the ethics procedures, participants will be randomly assigned to one of the following two conditions: 1. CBT delivered in face‐to‐face: The gold standard treatment developed by Dugas et al. will be applied in weekly sessions where the patient and the therapist are in the same room. 2. CBT delivered in videoconference: The gold standard treatment developed by Dugas et al. will be applied in weekly sessions where the patient is in a room at the local site (i.e. city where the patient attends the treatment) and the therapist is in a different room in the remote site (i.e. a different city, where the therapists delivers the treatment). For both conditions, the treatments will be similar to what is being used in other research centers, with treatment beginning by a case conceptualization, followed by identification of worry processes, cognitive restructuring of the usefulness of worries, building tolerance to uncertainty with in vivo exposure, building problem solving skills, exposure in imagination to worse fear scenarios, and relapse prevention. The only difference between the two conditions is that patients and therapist may be, or not, in the same room / city. All treatments will last 15 sessions and will be supervised by the principal investigator and the co‐investigators. The treatment will be delivered by graduate students experienced in CBT and the treatment of anxiety disorders. A standardized treatment will be conducted for 15 weekly 60‐minutes sessions delivered by experienced therapists. Treatment fidelity will be enhanced by the use of treatment manuals and weekly supervisions. Adherence to the research protocol will be assessed regularly by independent raters who will review videotapes of therapy sessions. CONDITION: Generalized anxiety disorder ; Mental and Behavioural Disorders PRIMARY OUTCOME: Severity of GAD symptoms on the Anxiety Disorders Interview Schedule (ADIS):; The ADIS is a semi‐structured interview rating the severity of each symptoms of GAD to provide a global severity rating. It is a common outcome measure in research on GAD. Inter‐rater reliability will be assessed and maintained during the entire study. Total score varies between 0 to 8.; The ADIS will be administered at baseline, post‐treatment and at the 6‐ and 12‐month follow‐ups. SECONDARY OUTCOME: 1. Penn‐State Worry Questionnaire:; This self‐report measures signs of GAD and the tendency to worry. The subject must indicate to which degree he or she agrees with 16 assertions typical people suffering from GAD. All items are rated on a 0 to 5 scale.; 2. Worry and Anxiety Questionnaire:; This questionnaire is a self‐rating of the severity of DSM‐5?s GAD symptoms measured by the ADIS. All symptoms are rated on a 0 to 8 scale.; 3. Intolerance of Uncertainty:; Participants rate 45 items assessing the core psychological mechanism of GAD, namely intolerance of uncertainty. This fear of uncertainty is the reason motivating patients to engage in ruminations and worries in order to anticipate and protect themselves from dreaded consequences of daily stressors. All items are rated on a 0 to 5 scale. ; All outcomes will be assessed at baseline, post‐treatment and at the 6‐ and 12‐month follow‐ups. INCLUSION CRITERIA: 1. Ambulatory man and woman 2. At least 18 years old and at most 75 years old 3. French speaking 4. Receiving a principal diagnosis of GAD based on DSM‐5 diagnostic criteria. Assessed with asemi‐structured diagnostic interview (ADIS) 5. If currently taking medication for GAD, pharmacotherapy must me stabilized (same type and dosage) for at least six months and the GAD remained stable and uncured (i.e. still meeting the diagnostic criteria). Note that there is no perfect solution to the problem of medication since most severe cases already receive Selective Serotonin Reuptake Inhibitor (SSRI) from their doctors when they seek psychological treatments (thus, recruiting non‐medicated participants would threaten the feasibility of the study and could lead to the selection of less severe cases) and stopping medication would induce other methodological problems (e.g., withdrawal symptoms, artificial peak of severity at pre‐treatment, ethical issues)