The brain-derived neurotrophic factor (BDNF) gene Val66Met polymorphism affects memory performance in older adults

Objective: Memory impairment is an important contributor to the reduction in quality of life experienced by older adults, and genetic risk factors seem to contribute to variance in age-related cognitive decline. Brain-derived neurotrophic factor (BDNF) is an important nerve growth factor linked with development and neural plasticity. The Val66Met polymorphism in the BDNF gene has been associated with impaired episodic memory in adults, but whether this functional variant plays a role in cognitive aging remains unclear. The purpose of this study was to investigate the effects of the BDNF Val66Met polymorphism on memory performance in a sample of elderly adults. Methods: Eighty-seven subjects aged > 55 years were recruited using a community-based convenience sampling strategy in Porto Alegre, Brazil. The logical memory subset of the Wechsler Memory Scale-Revised was used to assess immediate verbal recall (IVR), delayed verbal recall (DVR), and memory retention rate. Results: BDNF Met allele carriers had lower DVR scores (p = 0.004) and a decline in memory retention (p = 0.017) when compared to Val/Val homozygotes. However, we found no significant differences in IVR between the two groups (p = 0.088). Conclusion: These results support the hypothesis of the BDNF Val66Met polymorphism as a risk factor associated with cognitive impairment, corroborating previous findings in young and older adults.

Crack-cocaine dependence and aging: effects on working memory

Objective: To compare the working memory (WM) performance of young adult crack-cocaine dependent users, healthy older adults, and a control group of healthy young adults. Methods: A total of 77 female participants took part in this study: 26 young adult crack-cocaine dependent users (CRK), 19 healthy older adults (HO), and 32 healthy younger adults (HC). All participants completed the N-back verbal task. Results: A multivariate analysis of covariance was performed. The model included education, income, and medication use as covariates. A group effect (F6,140 = 7.192, p < 0.001) was found. Post-hoc analyses showed that the performance of the CRK and HO groups was reduced compared to the HC group in two N-back conditions. No differences between the HO and CRK groups on WM performance were found. Conclusions: CRK participants perform similar to HO participants on a WM task, despite the well-known effects of age on WM and the young age of CRK. These data point to a possible parallel between cognitive declines associated with crack use and developmental aging.