Behavioral activation (BA) is an evidence-based psychotherapy for depression. BA a treatment for depression very effective, even for patients who have not had success with other psychological therapy. BA shifts away from cognitions and feelings to focus on a patient’s behavior and environment. At the end of BA psychotherapy treatment, patients can continue to use the skills they have learned on their own, self-regulating their own cognitive behavior, without having to depend on therapists to help them in the future. In Vietnam common treatment for depression includes antidepressant medications and some other sedative medications. In all treatments of psychological disorders, especially depression, using BA therapy is the best treatment for patients. However, studies in Vietnam have not yet been conducted to assess the effectiveness of short-term psychotherapy for depressed patients of all ages, studies of middle-aged and elderly people are not yet available
only a few studies focused on behavioral psychological disorders in adolescents. In this article, I study three different age groups of subjects: adolescents, middle-aged, and depressed elderly adults using BA therapy in a psychiatric hospital in Vietnam. The results indicated that behavioral activation (BA) therapy was effective in the treatment of depression in adolescents, middle-aged and elderly adults. The results also showed the limitations of BA application to depression treatment among the chosen patients.