Efeitos do exercício físico em marcadores inflamatórios, neurotróficos, imunológicos e em neurotransmissores em pessoas com depressão: uma revisão sistemática e metanálise

Abstract

Depression is one of the most disabling illnesses in the world and the worldwide burden associated with lost work days due to depression and anxiety are estimated to be 2.3 trillion dollars by the year 2030. The standard treatment for depression, psychotherapy, and medication do not help to improve the physical-functional capacity of these individuals. On the other hand, physical exercise provides several physical and emotional benefits, reducing the appearance of comorbidities, exerting antidepressant effects, and improving the quality of life of this population. The present review aimed to identify whether chronic physical exercise effects were sufficient to modify blood biomarkers in adults with depression and if these changes were related to changes in depressive symptoms. Searches were performed between August 2021 and February 2022 in six different databases (PubMed, PsycINFO, Cochrane Library, SportDiscus, Embase, Scopus, and Web of Science). The present study included randomized clinical trials (RCT) published in English, Portuguese, or Spanish, with no restriction on the year of publication. In addition, subjects should have a diagnosis of unipolar depression, and the RCTs should use a model of chronic physical exercise and present measurements of blood markers collected before and after the intervention. Studies with children and adolescents, animal models, and people diagnosed with another psychiatric disorder (in addition to depression) were excluded. A 3,865 studies were found, leaving 2,507 after removing the duplicates. Of these, 2,459 titles and abstracts were removed, leaving 48 full texts for reading. Twelve studies were selected to compose this review, 9 being included in the meta-analysis. After statistical analysis, physical exercise reduced depressive symptoms, and the reduction was associated with an increase in the circulating levels of some biomarkers, such as BDNF and kynurenine. These changes were observed when comparing groups that performed aerobic physical exercises with those that remained in a control group, performing some other activity or just being a passive control. It can be concluded that, despite the differences in the samples and the activities performed in the control groups, aerobic exercise changed circulating levels of neurotrophins and that the increase in these levels was related to the reduction of depressive symptoms.