APOE & BDNF polymorphisms interact to affect memory performance at baseline in adolescent athletes

ABSTRACT

Although several single-nucleotide polymorphisms have been associated with cognitive functioning in a variety of healthy and clinical samples, the influence of gene × gene interactions on cognition is poorly understood. The purpose of this study was to examine interactive relationships between apolipoprotein E (APOE) and brain-derived neurotrophic factor (BDNF) polymorphisms on cognitive functioning in a sample of healthy adolescent athletes. Participants of this cross-sectional study included 78 student-athletes (52.6% male; age: M = 13.31, SD = 1.23). Athletes completed the Immediate Post-Concussion and Cognitive Testing (ImPACT) computerized battery at baseline. APOE and BDNF genotypes were determined with buccal samples (APOE ε4+: n = 26; APOE ε4-: n = 52; BDNF Met+: n = 23; BDNF Met-: n = 55). Two-way analyses of variance (ANOVAs) were used to evaluate the associations among APOE (ε4+ vs. ε4-) and BDNF (Met+ vs. Met-) genotypes and the ImPACT cognitive composites and two-factor model. No main effects were observed for either APOE or BDNF genotypes across the cognitive outcomes. However, there was a significant APOE × BDNF genotype interaction for the verbal (p=.009, η_p²=.091) and visual (p = .012, η_p²=.082) memory composites and the memory factor (p = .001, η_p²=.133), such that ε4+/Met+ carriers demonstrated poorer performance relative to other allele combinations. No significant interactions were observed for the visual motor speed (p = .263, η_p²=.017) or reaction time (p = .825, η_p²=.001) composites or the speed factor (p = .205, η_p²=.022). Our findings suggest an important relationship between APOE and BDNF genotypes on verbal and visual memory performance in healthy adolescent athletes. Clinicians may use this information to offer individualized concussion management based on individual athlete characteristics related to genetics and cognition.

KEYWORDS:

• Cognitive function
• ImPACT
• sports
• genes

Acknowledgments

No additional acknowledgments to report for this paper.

Disclosure statement

Dr. Ruben Echemendia is a paid consultant for the NHL and co-chair of theNHL/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. KER is a part-time employee of the National Hockey League.

Notes

¹ η_p² = partial eta squared; small =.01, medium =.06, large =.14 (Field, 2013).

Additional information

Funding

The work was supported by the APA Society for Clinical Neuropsychology (Division 40).