Dados do Trabalho

Título

Genetics, rhythm, and cognition: effect of BDNF Val66Met polymorphism on adolescents’ circadian rhythms and attentional performance

Introdução

Cognitive performance is impacted by sleep habits, chronotypes and genetic characteristics. Variations in circadian mechanisms generate different individual preferences timing for sleep and activity, called chronotypes, affecting the performance of cognitive skills during the day. There is a tendency to eveningness during adolescence. The Val66Met (rs6265) polymorphism, in the human Brain-Derived Neurotrophic Factor gene, plays a significant role in the cognitive performance and circadian rhythm patterns.

Objetivo

This study aimed to evaluate the effect of BDNF Val66Met polymorphism on adolescents’ circadian patterns and cognitive performance on attention tests.

Métodos

Eighty-five healthy high school students were included. All students were evaluated in the morning by the Psychological Battery for Attention Assessment, which assessed the ability to concentrate, and the divided and alternate attention. Students were categorized as carriers and non-carriers of the rs6265 polymorphism by using the TaqMan rt-PCR technique. Their chronotype profiles were classified as Morningness-Eveningness according to the score of Horne and Ostberg questionnaire. A subgroup of 42 students was objectively assessed for their sleep-wake habits, wearing an actigraph for nine days.

Resultados

Carriers of the BDNF polymorphism performed better than the non-carriers in the alternate task (107.23±12.06 vs. 98.65±17.61; 95%CI=-0.74–15.0). No association was found between the presence of the r6269 polymorphism and the Morningness-Eveningness scale score (95%CI=-5.68-4.0). With regard to actigraphic results, the carriers of the polymorphism showed significant differences, compared to non-carriers, in the Total Sleep Time (6.48±0.69 vs. 5.97±0.65; 95%CI=0.038-0.98), Total Time in Bed (7.33±0.63 vs. 6.79±0.80; 95%CI=-0.024-1.07) and Social Jet Lag (2.43±0.95 vs. 1.68±1.04; 95%CI=0.026-1.47).

Conclusões

The presence of BDNF polymorphism demonstrated a partial and counterintuitive impact on attentional performance, affecting only alternate attention. The genetic trait studied showed an impact on activity-rest rhythms, when objectively measured by actigraphy.

Palavras -chave

sleep, circadian rhythm, BDNF Val66Met, attention, adolescence.