Major depression is a mental illness that seriously threatens public health, leading to disability, reduced quality of life, economic burden, and premature death. It is estimated that 18.4% of the world's population lived with depression between 2005 and 2015, and it is projected to be a leading cause of global disease burden by 2030. Major depressive disorder manifests with symptoms such as decreased interest and desire, a depressed mood, increased or decreased sleep and appetite, feelings of worthlessness and guilt, decreased energy, suicidal thoughts and attempts, leading to significant impairment in functioning. Choosing the appropriate treatment for depression and taking measures to improve the individual's functionality quickly, shorten hospital stays, and reduce the number of hospitalizations are crucial. In addition to pharmacological treatment, clinical guidelines recommend the combined use of pharmacological and psychosocial interventions in the treatment of depression. The mindfulness-based cognitive therapy, which forms the basis of the psychoeducation planned for this study, was developed as an 8-week group approach. Theoretical studies examining emotion regulation mechanisms have indicated that mindful awareness is a fundamental mechanism for emotion regulation. The literature suggests a negative correlation between mindful awareness and the severity of depressive symptoms and difficulty in emotion regulation. Furthermore, despite numerous descriptive, correlational, and experimental studies on major depression, no studies have been found demonstrating the effect of mindful awareness-based psychoeducation on emotion regulation difficulties, distress tolerance, and symptom severity in patients diagnosed with major depression. This study, therefore, differs from existing research and will make a significant contribution to the literature.

Individuals with depression are emotionally pessimistic, unhappy, and hopeless. They experience inner turmoil and restlessness, and even activities they previously enjoyed no longer bring them pleasure. They also feel sad and lonely. Their interest in their surroundings decreases, and their negative emotions increase (Demir, 2015). Another factor associated with depression is distress tolerance, defined as the ability to withstand negative emotional states (Rette et al., 2021). It has been noted that individuals who have difficulty demonstrating distress tolerance show more depressive symptoms. Intolerance encompasses deficiencies in a person's ability to tolerate negative emotions (Çaylak, 2021). In depression, which negatively affects individuals' quality of life and functionality, and also leads to workforce and economic losses and suicide attempts, selecting the appropriate treatment and taking necessary measures to improve the individual's functionality in a short time, shorten hospital stays and reduce the number of hospitalizations are extremely important (Başoğul and Buldukoğlu, 2015; Çelik and Hocaoğlu, 2016; Lopez and Murray, 1998; Greenberg et al., 2021; Tamam et al., 2012). Pharmacological treatment alone is not sufficient to treat depression (Foroughi et al., 2020). In this context, clinical guidelines recommend the combined use of pharmacological and psychosocial interventions in the treatment of depression (Başoğul and Buldukoğlu, 2015). Psychosocial interventions include health education and interventions that focus on psychological or social factors rather than biological factors (Ruddy and House, 2005). Through psychosocial interventions, patients learn how to cope with their problems and their adherence to treatment increases (Foroughi et al., 2020). In today's world, where the search for new solutions for the treatment of depression continues, various psychosocial interventions are being applied. A review of national and international literature reveals research conducted with different study groups on the prevalence, causes, and treatment options of depression (Çalık and Altaş, 2011; Koruç and Bayar, 2004). All research indicates that difficulties in emotion regulation processes play a role in the emergence and persistence of depressive symptoms that impair cognitive, physical, and behavioral functioning in daily life. One of the situations that makes adaptation difficult by causing physical or mental distress and threats to the individual is stress (Baltaş and Baltaş, 2010). While some events can trigger a stress response, the stress response begins with a mental interpretation of the situation, leading to the decision that it is dangerous (Uçar, 2004). The ability to accept negative emotional situations, regulate emotions, and tolerate distress-which means constructing emotions to prevent or alleviate negative emotional states-is crucial for coping with difficulties and maintaining health. Individuals with low distress tolerance focus on negative emotions, stating that their emotions negatively affect their lives and that they are exhausted (Simons and Gaher, 2005). Theoretical studies examining emotion regulation mechanisms have indicated that the fundamental mechanism of mindful awareness is emotion regulation. A review of the literature reveals that the prevailing view is that there is a negative correlation between mindful awareness and difficulty in emotion regulation. Current studies indicate that as individuals' levels of mindful awareness increase, the difficulties they experience related to emotion regulation decrease (Çelik, 2020). The literature also supports the idea that mindful awareness is a fundamental mechanism (Akkuzu et al., 2023). A study conducted on university students demonstrated the effect of a mindful awareness-based cognitive therapy program on the levels of depressive symptoms in individuals. Although many descriptive, correlational, and experimental studies have been conducted on major depression, no study has been found that demonstrates the effect of mindfulness-based psychoeducation on emotion regulation difficulties, distress tolerance, and symptom severity in patients diagnosed with major depression. This study differs from previous studies in this respect. It is believed that the data obtained from this study can help provide scientific information on the effect of mindfulness-based psychoeducation on emotion regulation difficulties, distress tolerance, and symptom severity in depressed patients, provide data to healthcare professionals on managing the symptoms of patients diagnosed with major depressive disorder, and contribute to guiding future research in this area.

Inclusion Criteria:

• Volunteering to participate in the study
• Residing in Gaziantep city center
• Not having any communication impediments
• Being between 18 and 65 years of age
• Being followed up as an outpatient with a diagnosis of depression according to DSM-V criteria
• Having been receiving treatment for depression for at least 6 months
• Being literate
• Not having been enrolled in such an educational program related to their illness within the last 5 years

Exclusion Criteria:

• Those diagnosed with another comorbid mental illness
• Patients with mental conditions that make cooperation impossible, such as intellectual disability or dementia
• Those who are illiterate
• Patients who do not consent to the interview
• Those receiving inpatient treatment

Individual patient data will not be shared in order to protect patient privacy and avoid stigmatization.

Participants in the experimental group will receive mindfulness-based psychoeducation, and the results will be evaluated by the researcher.