Background Cognitive-Behavioral Therapy (CBT) has a signi cant adjunctive effect in the treatment of Major Depressive Disorder (MDD), however its uses as monotherapy is less explored, mainly the group-based approaches. Methods We assessed the responses of distinct psychophysiological domains after a intervention using groupbased CBT (gCBT, 16 weeks) in drug-free patients with mild-moderate MDD (n = 20; women = 11) and to compare with a healthy control group (n = 25, women = 13). Results Treatment resulted in 65% of response and 55% of remission rates. Reductions in depressive and anxiety symptoms and increase in self-esteem and sleep quality were observed as responses of gCBT. After treatment patients regulated their previous deregulated salivary cortisol awakening response (CAR) and sleep quality to healthy parameters. These improvements were correlated among themselves and dependent of remission condition. Remitted patients showed large progresses than non-remitted patients, who signi cantly changed only serum cortisol and self-perceived depressive symptoms. Further, better baseline sleep quality was predictor of remission. Conclusion These psychophysiological changes in response of gCBT support its use as tool with low cost and no side effects for treatment of mild-moderate major depression, as well as suggests a stronger exploration of these psychological domains in psychotherapies and stimulates furthers studies of neurobiology of MDD and alternatives treatments. Trial registration U1111-1215-4472. Registered 21 August 2018, http://www.ensaiosclinicos.gov.br/rg/RBR-3npbf8/ [38, 39]. However, studies that have measured the effects of CBT as a monotherapy on cortisol levels of MDD patients are few and inconsistent [40, 41]. Thus, this study investigated the responses of distinct psychophysiological domains, such as depression and anxiety symptoms, self-esteem, sleep quality and cortisol levels (salivary and serum), in MDD patients under group CBT monotherapy treatment. We expected to nd a reduction of depressive and anxious symptoms, associated with increases in self-esteem and in sleep quality, as well as an adjustment of cortisol levels, especially in remitted patients. Methods This open-label trial was conducted at the Federal University of Rio Grande do Norte (UFRN) between 2018-2019. It has been approved by the UFRN Human Ethics Committee (# 2628,202) and registered at http://clinicaltrials.gov (U1111-1215-4472). The procedures of this study comply with the ethical standards of the relevant national and institutional committees for human experimentation and with the Declaration of Helsinki of 1975, revised in 2008. All subjects provided written informed consent prior to participation and it was ensured freedom to withdraw from the study at any time and without any prejudice. All study's information has been kept con dential.

BackgroundCognitive-Behavioral Therapy (CBT) has a significant adjunctive effect in the treatment of Major Depressive Disorder (MDD), however its uses as monotherapy is less explored, mainly the group-based approaches.MethodsWe assessed the responses of distinct psychophysiological domains after a intervention using group-based CBT (gCBT, 16 weeks) in drug-free patients with mild-moderate MDD (n = 20; women = 11) and to compare with a healthy control group (n = 25, women = 13).ResultsTreatment resulted in 65% of response and 55% of remission rates. Reductions in depressive and anxiety symptoms and increase in self-esteem and sleep quality were observed as responses of gCBT. After treatment patients regulated their previous deregulated salivary cortisol awakening response (CAR) and sleep quality to healthy parameters. These improvements were correlated among themselves and dependent of remission condition. Remitted patients showed large progresses than non-remitted patients, who significantly changed only serum cortisol and self-perceived depressive symptoms. Further, better baseline sleep quality was predictor of remission.ConclusionThese psychophysiological changes in response of gCBT support its use as tool with low cost and no side effects for treatment of mild-moderate major depression, as well as suggests a stronger exploration of these psychological domains in psychotherapies and stimulates furthers studies of neurobiology of MDD and alternatives treatments.Trial registrationU1111-1215-4472. Registered 21 August 2018, http://www.ensaiosclinicos.gov.br/rg/RBR-3npbf8/