Evaluation of the effects of aerobic exercise interventions on levels of brain derived neurotropic factor (BDNF) in adults with major depression.

Abstract 1.1 Objectives To evaluate the effects of aerobic exercise interventions on plasma and serum brain derived neurotropic factor in adults with a clinical diagnosis of major depression disorder (MDD). 1.2 Search Strategy Using pre-selected keywords, a range of electronic databases Cochrane, Cinahl, Embase, Psychinfo, Medline, Sciencedirect, Webofscience, Scopus, Ebsco and Google Scholar were searched between June and July 2016. 1.3 Selection Criteria Inclusion criteria were male and females over the age of 18 with a confirmed clinical diagnosis of MDD. Eligible studies included those that evaluated levels of serum or plasma brain derived neurotropic factor (BDNF) in response to aerobic exercise intervention. Studies published in English up to the date of 2016 and with full text available were included. 1.4 Data collection and Analysis The methodological quality of articles was evaluated using the Effective Public Health Practice Project tool (EPHHP.) Evidence was graded as either 1 - Strong, 2 - Moderate, 3 - Weak. 1.4 Results Of an initial 772 studies identified, 16 full articles were screened and 11 met the inclusion criteria. Sample sizes ranged between 348 and 12 participants. Three studies were graded as "strong", five as "moderate" and three as "weak". All eleven studies found that aerobic exercise improved MDD symptoms but none identified statistically significant increases in plasma or serum BDNF levels. 1.5 Conclusions From the findings, no statistically significant increases in BDNF were reported, although the evidence reviewed suggests that aerobic exercise intervention may improve depressive symptoms. Further research using higher quality and more focused research with more homogenous samples and approaches are required before any recommendations can to be made around the intensity and duration of aerobic exercise that significantly increases BDNF levels in adults with MDD.msc_physpreunpub2948_ethesesunpu