BDNF Val is considered a risk allele for patients with poststroke dementia, and it was found that ischemic stroke patients with a heterozygous Val/Met genotype developed cognitive impairment earlier than those with a Met/Met homozygous genotype and had significantly reduced survival (Kim et al., 2012; Rezaei et al., 2016). The gene discussed is BDNF; the disease is Cognitive impairment.