BDNF and dementia: When exploring the synergistic effects of BDNF, APOE, and HbA1c (glycated hemoglobin) on cognitive decline over 10 years in adults without dementia, Persson et al. found joint effects on memory decline in BDNF × APOE × age, with the subjects carrying the Met allele, as well as at least one copy of the APOE ε4 allele, showing magnified effect sizes with increasing age on memory decline, while the homozygote Val subjects carrying the ε4 allele showed a decreased slope [73].