Group Cognitive Evolutionary Therapy for Depression

The goal of this clinical trial is to measure the effects of Group Cognitive Evolutionary Therapy on mental health, especially on depressive symptoms and anxiety.

Participants will be allocated in one of two conditions: (1) Group Cognitive Evolutionary Therapy (intervention) or (2) Waitlist. The intervention will consist of two 8-hour sessions of Group Cognitive Therapy, in two consecutive days.

The Group Cognitive Evolutionary Therapy group will be compared to the waitlist group to test the efficacy of the intervention.

The aim of the study is to assess the efficacy of Group Cognitive Evolutionary Therapy on depressive symptoms and other indicators of mental health for people with moderate to moderately severe depressive symptoms. This clinical trial will provide essential insights into the potential benefits of this form of therapy. The results will contribute to the development of a short, economical and effective method of enhancing mental health for patients with moderate depressive symptoms.

After recruitment, participants will be randomly assigned to one of two conditions: (1) Group Cognitive Evolutionary Therapy (intervention) or (2) Waitlist.

The intervention group will participate in two 8-hour sessions of Cognitive Evolutionary Therapy over two consecutive days, in groups of no less than 5 and no larger than 8 people. These groups will be led by licensed psychologists with extensive knowledge of evolutionary psychology and cognitive evolutionary therapies.

Both groups will be evaluated at (1) pre-intervention (baseline), (2) one week after the intervention, (3) three months after the intervention and (4) six months after the intervention.

G\*Power analysis yields a total of N = 44 (f = 0.25, power = 0.95) for the two conditions.

The statistical analysis plan includes the analysis of primary and secondary outcomes, which will be assessed using predefined measures described at the measures section. Additionally, the investigators will assess various predictors to gain insights into the factors influencing intervention outcomes. These predictors will be measured using specific instruments, including screeners (Diagnostic and Statistical Manual, Fifth Edition - Text Revision Self-Rated Level 1 Cross-Cutting Symptom Measure-adult version and The Personality Inventory for Diagnostic and Statistical Manual, Fifth Edition-Brief Form-adult version), and the Adverse Childhood Experiences questionnaire to assess adverse childhood experiences.

Besides demographic assessors and the above mentioned instruments, The Evolutionary Fitness Scale will be used both to determine predictors for the intervention outcome and as an assessment tool for the topics of interventions for each subject, this being a central part of Cognitive Evolutionary Therapy.

Eligibility Criteria:
Inclusion Criteria:

* moderate to moderately severe depressive symptoms
* age 18 to 65

Exclusion Criteria:

* severe personality traits (antagonism, impulsivity, disinhibition, psychoticism)
* formally diagnosed with a severe mental disorder
* currently participating in any ongoing therapeutic intervention for mental health.