Depression is a serious mood disorder affecting approximately 175 million people worldwide, with a significant increase after the pandemic. Research on the possibilities of interventions in this disorder is polarized between those from a biological and pharmacological perspective and those that consider them insufficient to deal with all its complexity. In this context, the perspective on multifactorial, multicultural and phenomenological of this suffering is emphasized, considering the underlying psychic origin of depressive symptoms, a privileged subject of a clinic with a psychological-phenomenological basis. Despite the urgency for answers, there is a lack of research on clinical-psychological interventions that consider a broader perspective of the phenomenon, indicating the need for studies that discuss the contributions of psychotherapy to the treatment of depression as well as the evaluation of the degree of therapeutic changes and the psychological processes involved in it. This research aimed to verify the effectiveness and efficiency of the Direct Approach to the Unconscious (ADI) Method used in the psychological clinic by Personal Integration Therapy (TIP) – ADI/TIP Method - in subjects suffering from depression. The ADI/TIP Method was created by the Brazilian psychologist R. Jost de Moraes (1936-2013), through her experiential clinical practice since 1975. It is presented as an Evidence-Based Practice in Psychology for Depressive Syndrome (EBPP), and finds its fundamentals in the phenomenological psychology of E. Husserl (1859-1938) and the phenomenological anthropology of E. Stein (1891-1942). Its therapeutic resources allow for a conscious and direct approach (without analysis or interpretation) of the psychic contents registered in the unconscious layer of consciousness, enabling the therapeutic-diagnosis of primordial psychoaffective livedexperiences, allowing changes in essential layers of subjectivity, in a short-term clinical psychological intervention (10 to 15 sessions) preceded by a preparatory phase. This research is distinguished as a mixed and prospective longitudinal study with a sample of 341 participants. Data collection was carried out in four stages: 1) initial phase; 2) final phase (immediately post-therapy); 3) longitudinal phase 01 (after three months); 4) longitudinal phase 02 (after six months). The psychotherapeutic process used was the ADI/TIP Method and the BDI-II was the quantitative data collection instrument. For the longitudinal analysis, the nonparametric Friedman statistical test was used, complemented by the Wilcoxon test with Bonferroni correction for post hoc analyses. The results indicated significant improvement in the final phase and partial maintenance over time. The analysis of individual trajectories confirmed the efficacy of the treatment, with 100% of the participants showing improvement in the final phase, with an average reduction of 80.5% in depression scores and 92.6% maintaining clinically significant improvement (≥50%) after six months. For the qualitative research, 15 participants were selected according to the scope and richness of the content of their individual psychotherapeutic trajectory, and the Generic Change Indicators Scale (GCI) was used for data analysis. The participants achieved the highest levels of change on the GCI, results that remained consistent. The qualitative discussion was based on the psychological-phenomenological theory that allowed a more comprehensive interpretation of the observed changes, connecting therapeutic advances to fundamental aspects of human existence. These results demonstrate the efficiency and effectiveness of the ADI/TIP Method in the treatment of depression within the scope of Clinical Psychology (psychotherapy), and it is suggested the increase in research into longitudinal psychological-clinical interventions that meet the demands of a science that contemplates the human being in all its integrality.
