A pilot study examining BDNF Val66Met polymorphism and biological sex: Relationships with baseline cognitive functioning in adolescent athletes

Abstract

The purpose of this exploratory study was to examine interactive relationships between a common brain-derived neurotrophic factor (BDNF) polymorphism (Val66Met) and biological sex on cognitive functioning in a sample of healthy adolescent athletes. Participants included 82 student athletes (age: M = 12.85 years, SD = 1.13) who were involved in a clinically-based sports-concussion management program. Athletes completed the ImPACT computerized battery at baseline and provided buccal samples for determination of their BDNF genotype. Two-way ANOVAs were used to evaluate the effect of BDNF genotype (Met+ vs. Met−) and sex (male vs. female) on cognitive functioning (subgroup n’s: Female/Met+ = 12, Female/Met− = 26, Male/Met+ = 12, Male/Met− = 32). ANOVAs revealed non-significant main effects for both BDNF genotype and sex across all four cognitive composites. However, there was a significant BDNF genotype by sex interaction for the visual-motor speed composite (p = .015; η_p² = .073), such that female Met carriers demonstrated better performance than male Met carriers. In contrast, no differences were found on visual-motor speed performance between females and males without a Met allele. Although these results will need to be replicated using larger samples, our preliminary findings lend support to the view that the Met allele may be somewhat neuroprotective in healthy adolescent females.

Keywords:

• Adolescents
• baseline
• BDNF
• gender
• genetics
• ImPACT

Acknowledgements

We would like to thank the Penn State Genomics Core Facility for their assistance with processing the genetic data for this study. Additionally, we would like to thank the athletes for their participation in this research.

Disclosure statement

Dr. Ruben Echemendia is a paid consultant for the NHL and co-chair of the NHL/NHLPA Concussion Subcommittee. He is also a paid consultant for Major League Soccer, the US Soccer Federation, and Princeton University Athletic Medicine. He is currently a Co-PI in a grant funded by the NFL and he occasionally provides expert testimony in matters related to mTBI and sports concussion. None of the remaining authors have conflicts of interest to report.

Notes

1 Sensitivity analyses were conducted removing athletes who failed additional contemporary ImPACT validity indicators (X’s and O’s Total Incorrect > 30 OR Impulse Control Composite > 30 OR Word Memory Learning Percent Correct < 69% OR Design Memory Learning Percent Correct < 50% OR Three Letters Total Letters Correct < 8). These indicators captured an additional four athletes leaving a total sample of 78. After removing these athletes, results remained the same. Therefore, the original sample was retained for all major analyses.

Additional information

Funding

This investigation was supported by a grant awarded to Dr. Merritt from the APA Society for Clinical Neuropsychology (Division 40). Furthermore, Dr. Merritt received salary support during the writing of this manuscript from a Career Development Award from the VA Clinical Science Research & Development Service (IK2 CX001952).