Associations of Later-Life Education, the BDNF Val66Met Polymorphism and Cognitive Change in Older Adults

Studying at university in later life slows cognitive decline: A long-term prospective study

INTRODUCTION

Declining cognition in later life is associated with loss of independence and quality of life. This decline in cognition may potentially be reduced or reversed through engaging in cognitively stimulating activities. This study examined the potential for university attendance in later life to enhance cognitive function in older adults.

METHODS

Cognitively unimpaired adults (n = 485, 69% female, median age 60 years) were given the opportunity to undertake free university study. Repeated neurocognitive assessment was performed over 7 years.

RESULTS

Participants in the university education group (n = 383) improved z = .02 SD (.01, .03) per year of the study compared to controls (P = .001; averaged across a battery of cognitive tests). The largest improvements were observed on tests of language and verbal learning, memory, and episodic memory.

DISCUSSION

Later-life university study was associated with improved cognitive trajectories. Later-life education may preserve cognitive function, specifically for functions associated with communication, social interaction, and maintaining independence.

Association Between Components of Cognitive Reserve and Serum BDNF in Healthy Older Adults

Background: The brain-derived neurotrophic factor (BDNF) protein has been shown to have a prominent role in neuron survival, growth, and function in experimental models, and the BDNF Val66Met polymorphism which regulates its expression has been linked to resilience toward the effects of aging on cognition. Cognitively stimulating activity is linked to both increased levels of BDNF in the brain, and protection against age-related cognitive decline. The aim of this study was to investigate the associations between serum BDNF levels, the BDNF Val66Met genotype, and components of cognitive reserve in early and mid-life, measured with the Lifetime of Experiences Questionnaire (LEQ). Methods: Serum BDNF levels were measured cross-sectionally in 156 participants from the Tasmanian Healthy Brain Project (THBP) cohort, a study examining the potential benefits of older adults engaging in a university-level education intervention. Multiple linear regression was used to estimate serum BDNF's association with age, education, gender, BDNF Val66Met genotype, later-life university-level study, and cognitively stimulating activities measured by the LEQ. Results: Serum BDNF in older adults was associated with early life education and training, increasing 0.007 log(pg/ml) [95%CI 0.001, 0.012] per unit on the LEQ subscale. Conversely, education and training in mid-life were associated with a -0.007 log(pg/ml) [-0.012, -0.001] decrease per unit on the LEQ subscale. Serum BDNF decreased with age (-0.008 log(pg/ml) [-0.015, -0.001] per year), and male gender (-0.109 log(pg/ml) [-0.203, -0.015]), but mean differences between the BDNF Val66Met polymorphisms were not significant (p = 0.066). All effect sizes were small, with mid-life education and training having the largest effect size ( η p 2 = 0.044). Conclusion: Education in both early and mid-life explained small but significant amounts of variance in serum BDNF levels, more than age or gender. These effects were opposed and independent, suggesting that education at different stages of life may be associated with different cognitive and neural demands. Education at different stages of life may be important covariates when estimating associations between other exposures and serum BDNF.

The BDNF Val66Met Polymorphism Modulates Resilience of Neurological Functioning to Brain Ageing and Dementia: A Narrative Review

Brain-derived neurotropic factor (BDNF) is an abundant and multi-function neurotrophin in the brain. It is released following neuronal activity and is believed to be particularly important in strengthening neural networks. A common variation in the BDNF gene, a valine to methionine substitution at codon 66 (Val66Met), has been linked to differential expression of BDNF associated with experience-dependent plasticity. The Met allele has been associated with reduced production of BDNF following neuronal stimulation, which suggests a potential role of this variation with respect to how the nervous system may respond to challenges, such as brain ageing and related neurodegenerative conditions (e.g., dementia and Alzheimer’s disease). The current review examines the potential of the BDNF Val66Met variation to modulate an individual’s susceptibility and trajectory through cognitive changes associated with ageing and dementia. On balance, research to date indicates that the BDNF Met allele at this codon is potentially associated with a detrimental influence on the level of cognitive functioning in older adults and may also impart increased risk of progression to dementia. Furthermore, recent studies also show that this genetic variation may modulate an individual’s response to interventions targeted at building cognitive resilience to conditions that cause dementia.