ABSTRACT
Introduction: Adolescents' cognitive performance is impacted by factors such as sleep habits, chronotypes and also genetic characteristics. The periods of human sleep and wakefulness are controlled by homeostatic and circadian factors, which the combination generates variations in the preferences for hours of activity and rest, called chronotypes. Chronotypic classification impacts cognitive skills such as logic and problem solving. In adolescence, there is a greater tendency to evening chronotype. The neural factor called BDNF, Brain- Derived Neurotrophic Factor, showed a significant role in cognitive performance variations as in different sleep patterns. The human BDNF gene has a frequent polymorphism called Val66Met, related to several cognitive functions and different patterns of sleep and circadian rhythm. Objective: Evaluate the association of BDNF Val66Met polymorphism with circadian patterns and cognitive performance on tests of attention, in high school students. Methods: High school students, aged between 15 and 17 years old were included in the study, whose cognitive attention skills were investigated by the Psychological Battery for Assessment of Attention. Their BDNF genotypes were determined by analyzing self-collected oral cell samples, which were amplified by real-time PCR using fluorescent probes. Chronotypic characteristics were evaluated by completing two morningness and eveningness scales. Because of the pandemic of COVID-19, a questionnaire about the presence of symptoms, in the previous days of the tests, was included. At present, volunteers are being evaluated through actigraphy. Results: Eighty-five adolescents were evaluated in that study. The average attention score of students who study in the afternoon was lower than individuals who study in the morning. The average score attention for the female gender was significantly lower than that obtained for the male gender. The students who reported symptoms of COVID- 19 had a significantly lower attention score. Lastly, there was no correlation between the chronotype defined by the scales, the performance in the attention test, or even the BDNF genotype of the participants. Conclusion: The central findings obtained, in the first phase of the study, complement the understanding of the associations between the parameters of cognition, chronobiology and genetic aspects. In the next phase, the use of actigraphy will make it possible to deepen these analyzes and conclusions.