The Effect of Physical Activity on Neurotrophin Concentrations and Cognitive Control in Patients With a Depressive Episode

BACKGROUND: Cognitive deficits occur in most patients with affective disorders. The role of neurotrophic factors (e.g., BDNF) as modulators of brain plasticity affecting neurocognitive abilities has been emphasized. Neurotrophin concentrations may change under the influence of various interventions, including physical activity. Selected studies have shown that cognitive function may also be affected by exercise. AIM: The aim of the study was to determine whether physical activity changes the concentration of neurotrophins and their receptors in patients with an episode of depression. It was also examined how one session of aerobic exercise affects cognitive control. METHODS: The study included 41 participants. The subjects were asked to exercise on a cycloergometer for 40 min with individually selected exercise loads (70% VO(2)max). Before and shortly after the exercise blood samples were acquired to perform blood assays (proBDNF, BDNF, TrkB, NGFR). The participants also performed a Stroop test twice—before the exercise and 10 min after its cessation. RESULTS: The single bout of physical exercise did not cause any significant changes in the concentration of neurotrophic factors. The SCWT results: both the mean reading time (29.3 s vs. 47.8 s) and the color naming time (36.7 s vs. 50.7 s) increased. The patients made more mistakes after physical exercise, both in part A (0.2 vs. 1.5) and B (0.6 vs. 1.5). The so-called interference effect decreased—the difference between naming and reading times was smaller after exercise (6.2 s vs. 2.4 s). No significant correlations were found between the concentrations of the studied neurotrophic factors and the Stroop test results. CONCLUSIONS: The results did not confirm changes in neurotrophin concentration under the influence of a single session of physical activity. The shortening of the interference time after exercise may be caused by practice effects. A significant limitation of the study is the use of the Stroop test twice in short intervals.