Abstract
IntroductionBrain‐derived neurotrophic factor (BDNF) has an important role in the neurogenesis and neuroplasticity of the brain. This systematic review was designed to examine the association between BDNF Val66Met (rs6265) polymorphism and four cognitive domains—attention and concentration, executive function, verbal fluency, and memory, respectively.MethodologyPrimary literature search was performed using search engines such as PubMed and Scopus. Observational studies that evaluated the neurocognitive performances in relation to BDNF polymorphism within human subjects were included in this review, while animal studies, overlapping studies, and meta‐analysis were excluded.ResultsForty of 82 reviewed studies (48.8%) reported an association between Val66Met polymorphism and neurocognitive domains. The proportion of the studies showing positive findings in cognitive performances between Val/Val homozygotes and Met carriers was comparable, at 30.5% and 18.3%, respectively. The highest percentage of positive association between Val66Met polymorphism and neurocognition was reported under the memory domain, with 26 of 63 studies (41.3%), followed by 18 of 47 studies (38.3%) under the executive function domain and four of 23 studies (17.4%) under the attention and concentration domain. There were no studies showing an association between Val66Met polymorphism and verbal fluency. In particular, Val/Val homozygotes performed better in tasks related to the memory domain, while Met carriers performed better in terms of executive function, in both healthy individuals and clinical populations.ConclusionWhile numerous studies report an association between Val66Met polymorphism and neurocognitive changes in executive function and memory domains, the effect of Met allele has not been clearly established.
Highlights
Brain-derived neurotrophic factor (BDNF) has an important role in the neurogenesis and neuroplasticity of the brain
As BDNF is highly expressed in regions of the central nervous system (CNS) that modulate learning and memory, it would be of interest to understand how the BDNF rs6265 polymorphism influence specific cognitive domains such as the attention and concentration, executive function, verbal fluency, and memory
There has been a cross-sectional study which found that the association between physical activity and episodic memory was mediated by BDNF polymorphism, as Val/Val homozygotes were found to perform significantly better than Met carriers if they were active in physical activity, showing how that environmental factor can be a consideration (Canivet et al, 2015)
Summary
The brain-derived neurotrophic factor (BDNF) belongs to the neurotrophin superfamily and has an essential role in the neurogenesis and neuroplasticity of the brain (Matsuo et al, 2009). The G196A polymorphism occurs in the proregion of BDNF, resulting in an amino acid substitution of valine for methionine at codon position 66 (Val66Met) This polymorphism change has been linked to aberrant sorting of pro-BDNF into secretory vesicles and decreased activity-dependent secretion of BDNF which constitutes the main process in the regulation of extracellular levels of BDNF (Wei et al, 2012). In view of the importance of BDNF in the central nervous system (CNS) and the functional consequences of its SNP, numerous genetic studies have evaluated the association between the BDNF rs6265 polymorphism with cognitive performance in various disease states. As BDNF is highly expressed in regions of the CNS that modulate learning and memory, it would be of interest to understand how the BDNF rs6265 polymorphism influence specific cognitive domains such as the attention and concentration, executive function, verbal fluency, and memory. This systematic review was conducted to evaluate the relevant studies regarding associations between the SNP Val66Met and neurocognitive domains
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