Moreira-Neto A. Effects of aerobic exercise with and without motor complexity on hopelessness, affective responses, and volume of the amygdala, thalamus, and nucleus accumbens in individuals with major depression from the Brazil's unified health system [thesis]. São Paulo: "Faculdade de Medicina; Universidade de São Paulo''; 2023. INTRODUCTION: Individuals with major depression (MD) present hopelessness, low affective responses (clinical outcomes), and volumetric reductions of the amygdala, thalamus, and nucleus accumbens (NAcc) (volumetric outcomes), which are associated with the severity of MD, mainly in individuals with low socioeconomic conditions. Although aerobic exercise (AE), such as walking and running, is one of the main low-cost interventions that decreases depressive symptoms and increases hippocampal volume, there are no studies analyzing the effects of AE on the outcomes mentioned in the present study. Additionally, it is important to test the hypothesis that AE with motor complexity (AEMC) could be more effective than isolated AE in improving clinical and volumetric outcomes, due to the fact that complex exercises present better brain responses than non-complex exercises. OBJECTIVE: To analyze and compare the effects of 24 weeks of AE and AEMC on hopelessness, affective responses (clinical outcomes), and volumetry of the amygdala, thalamus, and NAcc (volumetric outcomes) in individuals with MD from the Brazil's unified health system Sistema Único de Saúde (SUS). METHODS: Forty individuals (>40 years) with MD diagnosed by the International Neuropsychiatric Interview (MINI) and with depressive symptoms evaluated through the Montgomery-Asberg Depression Rating Scale (MADRS) completed the study. Hopelessness was measured through the Beck Hopelessness Scale (BHS), affective responses through the Feelings Scale (FS), and volumetric outcomes were evaluated through 3T magnetic resonance imaging morphometry and analyzed by FreeSurfer software. All individuals used antidepressants and were randomized by the MADRS score and the number of depressive episodes into three groups: No Exercise (NE, n=12), AE (n=14), and AEMC (n=14). The AE and AEMC groups performed 60 minutes of exercise, twice a week, for 24 weeks (on non-consecutive days). Effect size (ES) with confidence interval (CI) was used to analyze the intra and between-group differences in hopelessness, affective responses, and volumetric outcomes. In addition, a multiple linear regression analysis (stepwise model) was performed to identify if the improvement (post-pre) of volumetric outcomes could explain the improvement of hopelessness and affective responses in the training groups. RESULTS: The AE group reduced the BHS score (ES= -0.73, CI= -0.15 to -1.31), increased the FS score (ES= 1.24; CI= 0.75 to 1.73), increased the volumetry of the left (ES= 0.27; CI= 0.07 to 0.46) and right (ES= 0.34; CI= 0.08 to 0.61) amygdala, left (ES= 0.33; CI= 0.06 to 0.60) and right (ES= 0.26; CI= 0.09 to 0.42) thalamus, and left NAcc (ES= 0.54; CI= 0.31 to 0.77). AEMC o...