Validation of a Dynamic Measure of Current Cognitive Reserve in a Longitudinally Assessed Sample of Healthy Older Adults: The Tasmanian Healthy Brain Project.

Cognitive reserve (CR) is a theoretical construct describing the underlying cognitive capacity of an individual that confers differential levels of resistance to, and recovery from, brain injuries of various types. To date, estimates of an individual's level of CR have been based on single proxy measures that are retrospective and static in nature. To develop a measure of dynamic change in CR across a lifetime, we previously identified a latent factor, derived from an exploratory factor analysis of a large sample of healthy older adults, as current CR (cCR). In the present study, we examined the longitudinal results of a sample of 272 older adults enrolled in the Tasmanian Healthy Brain Project. Using results from 12-month and 24-month reassessments, we examined the longitudinal validity of the cCR factor using confirmatory factor analyses. The results of these analyses indicate that the cCR factor structure is longitudinally stable. These results, in conjunction with recent results from our group demonstrating dynamic increases in cCR over time in older adults undertaking further education, lend weight to this cCR measure being a valid estimate of dynamic change in CR over time.

Further education improves cognitive reserve and triggers improvement in selective cognitive functions in older adults: The Tasmanian Healthy Brain Project.

INTRODUCTION: The strong link between early-life education and subsequent reduced risk of dementia suggests that education in later life could enhance cognitive function and may reduce age-related cognitive decline and protect against dementia. METHODS: Episodic memory, working memory, executive function, and language processing performances were assessed annually over 4 years in 359 healthy older adults who attended university for a minimum of 12 months (intervention) and were compared against 100 healthy adult controls. RESULTS: Multiple group latent growth curve modeling revealed a significant improvement in language processing capacity over time in the intervention group. No changes were detected for episodic memory, working memory, or executive function. DISCUSSION: These results suggest that complex mental stimulation resulting from late-life further education results in improved crystallized knowledge but no changes to fluid cognitive functions.

The BDNF Val66Met polymorphism moderates the effect of cognitive reserve on 36-month cognitive change in healthy older adults.

INTRODUCTION: Cognitive reserve (CR) and BDNF Val66Met are independently associated with the rate of cognitive decline in preclinical Alzheimer's disease. This study was designed to investigate the interactive effects of these variables on 36-month cognitive change in cognitively intact older adults. METHODS: Data for this investigation were obtained from 445 community-residing participants of the Tasmanian Healthy Brain Project, who underwent genetic screening and annual assessment of neuropsychological, health, and psychosocial function. RESULTS: Our main result was that BDNF Val66Met moderated the relationship between baseline CR and change in executive function performance, in that CR-related differences in function decreased across the follow-up period in BDNF Val homozygotes, but became more pronounced in BDNF Met carriers. Similar effects were not observed within the other memory- and language-related cognitive domains. DISCUSSION: Inheritance of BDNF Met may be associated with a detrimental influence on the relationship between CR and cognitive change in cognitively intact older adults, but this effect may be restricted to the executive function domain.

Variations in the APOE allele or BDNF Val66Met polymorphism are not associated with changes in cognitive function following a tertiary education intervention in older adults: the Tasmanian Healthy Brain Project.

The apolipoprotein (APOE) ε4 allele and the Met variant of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism are associated with reduced cognitive function in older adults. The aim of this study was to examine the independent and interactional effect of the APOE ε4 allele and BDNF Val66Met polymorphism on cognitive function in a cohort of healthy older adults who had undertaken further university level education. Multiple group latent growth curve modeling revealed no change in cognitive function over time in APOE ε4-carriers or in BDNF Met-carriers, nor in carriers of both APOE-ε4 and BDNF-Met alleles. Further, the results indicate that allelic variation in either APOE or BDNF does not modify the beneficial effects of a university-based education intervention on cognitive function over a 4-year period following the intervention.