Author(s): DUDERSTADT, Y., SCHREIBER, S., BURTSCHER, J., SCHEGA, L., MUELLER, N.G., BRIGADSKI, T., BRAUN-DULLAEUS, R., LESSMAN, V., MUELLER, P., Institution: UNIVERSITY HOSPITAL MAGDEBURG, Country: GERMANY, Abstract-ID: 2489

INTRODUCTION:
Brain-derived neurotrophic factor [BDNF] is a crucial mediator of cognitive abilities, like long-term memory. Previous investigations indicate that different factors (e.g., physical activity, nutrition, psychosocial stress, hypoxia) can influence blood BDNF levels in humans. Currently, there is inconsistency in the reported results concerning the effects of controlled and moderate normobaric hypoxia [NH] on BDNF. Therefore, we investigated the impact of passive exposure to NH on BDNF levels in blood serum and plasma, alongside its effects on cognitive functions.
METHODS:
In a controlled crossover study 25 healthy adults (25.8±3.3yrs., 15 female) were randomly exposed to normoxia [NOR] and NH (80-85 % peripheral oxygen saturation [SpO2]). The experiment started with a passive 30-min supine rest under normoxic conditions followed by a 90 min continuation of passive NOR or NH. Serum and plasma blood samples were collected every 15 min for the entire exposure length of 120 min via peripheral venous catheter except for the final sample, which was taken simultaneously from the contralateral arm via butterfly needle. Heart rate and SpO2 were continuously measured. Before and after each exposure, cognitive tests of short-term memory, working memory and attention were performed.
RESULTS:
The 30 min of passive rest under NOR reduced the blood serum (p<.001) and plasma (p<.001) BDNF levels significantly. An extension of passive NOR have resulted in a continued decline in blood serum BDNF levels after an additional 45 min (p=0.18). Likewise, plasma BDNF levels exhibited further reductions after 30 min (p=.040) and 90 min (p=.005). Under NH BDNF levels remained stable. The two methods of blood collection (peripheral venous catheter vs. butterfly needle) did not differ. Furthermore, no effects on short-term memory or working memory functions were observed following NOR or NH. However, significant improvements in attention were observed after both conditions.
CONCLUSION:
As expected, exposure to a passive NOR leads to a reduction in BDNF levels in serum and plasma. However, 90 minutes of NH exposure has no such negative effect. There is also no acute negative effect on short-term memory, working memory or attention. These results can therefore serve as an initial basis for counteracting the decline in BDNF caused by physical inactivity with the help of controlled hypoxia. This study also shows the need for a standardized protocol for future studies determining BDNF levels determinations in blood.