The magnitude of combined training-induced changes in executive functions is related to pre-training BDNF levels in middle-aged and older adults with Type 2 Diabetes Mellitus

Abstract

Background: Many cognitive functions are affected by Type 2 Diabetes Mellitus (T2DM). Aerobic plus resistance exercise training, known as combined training (CT), may mitigate or reverse the T2DM-related cognitive impairment by improving metabolic control. Brain-derived neurotrophic factor (BDNF) seems to modulate the cognitive functions of healthy and T2DM adults. However, the CT-effects on BDNF levels of T2DM subjects need to be better elucidated. Aim: To analyze the effects of 8-week CT on circulating BDNF levels of T2DM subjects. Additionally, were investigated the relationship between BDNF levels and CT-induced changes in executive functions and long-term memory of T2DM subjects. Methods: Thirty-five (63 ± 8 years old) T2DM subjects of both sexes were allocated to CT (n=17, thrice-weekly during 8 weeks) or control group (CONT, n=18). Executive functions (evaluated through Trail making test, Stroop color task, and Digit Span), long-term memory (evaluated through the simplified version of Taylor Complex Figure Test), and plasma samples were analyzed pre- and post-intervention. Results: CT induced higher improvements in executive functions composite z-score than CONT (d= 1.31). BDNF levels were not statistically altered (pre-CT: 179±88 pg/ml; post-CT: 148±108 pg/ml; pre-CONT: 163±71 pg/ml; post-CONT: 141±84 pg/ml, p> 0.05). However, pre-CT BDNF levels were positively related to CT-induced changes on executive functions composite z-score (r= 0.71), inhibitory control (r= 0.58) and cognitive flexibility (r= 0.56). Conclusion: CT improved executive functions and higher pre-training BDNF levels have been correlated to those CT-induced improvements on executive functions, independently of the training alterations in resting BDNF levels of T2DM subjects.