BDNF and Mental deterioration: Genetic markers: Associations between genetic polymorphisms and the development of cognitive decline have been evaluated, mainly involving genes associated with neurogenesis, repair and neuroplasticity after neuronal damage such as APOE ε4 and Brain-Derived Neurotrophic Factor (BDNF). In a study by Ahles et al [46], long-term survivors of breast cancer (mean 8.8+/−4.3 years after treatment) with at least one APOE ε4 allele scored significantly lower in visual memory (p < 0.03) and spatial ability (p < 0.05) [46].