Cognitive super-aging versus typical aging in community-dwelling older adults: Longitudinal trajectories in global cortical thickness over six years

Background It is common for older adults to experience decline in some cognitive functions with increasing age. Importantly, a subset, usually referred to as super-agers (SA; Rogalski, et al., 2013, J Cog Neurosc, 25: 29-36) live to an old age whilst continuing to maintain cognitive function at levels similar to demographically-matched peers at least 20-30 years their junior. The current study reports trajectories of change in cortical thickness on a well-defined group of SAs vs. typical agers (TA) followed longitudinally over six years in the Australian Imaging, Biomarkers & Lifestyle Study (AIBL) (Ellis et al., 2009, Int Psychogeriat, 2: 672-87). Methods Super-Agers were defined as individuals aged 60+ who scored in the normative range for individuals aged 30 – 44 on the CVLT-II, a test of verbal episodic memory, at baseline and two consecutive time-points 18 months apart. SAs additionally must have performed in the unimpaired range in all other cognitive domains, as compared to same-aged peers. Typical agers must have scored within the normal range on all cognitive measures compared with same-aged peers. This report describes data from 21 SAs and 24 TAs. The TAs were chosen from a larger group matched on age, education and gender to the SA group. All participants completed brain magnetic resonance imaging every 18 months for six years. We conducted multiple linear mixed models analyses to assess the association between preservation of cortical thickness in SAs and TAs. Results From 34 regions of interest identified as potentially differentiating SAs from TAs from previous neuroimaging studies, our results were consistent in finding greater cortical thinning amongst TAs in 20 of these regions (p-values ranging between ≤ .000 and .047), with an additional five regions at trend level (p-values ranging between ≥ .05 and .073). Using false discovery rates, we found significantly preserved thickness in three regions not previously reported including left superior parietal gyrus, left precuneus, and left paracentral lobule. Conclusions SAs and TAs displayed similar cortical thickness at baseline (p >.40), but showed different trajectories over time. The findings will be discussed in the context of current models of cognitive and brain reserve

AU‐ARROW (Australia)

Background The highly encouraging findings from the Finnish Geriatric Intervention Study (known as FINGER) led to the global initiative for dementia risk reduction known as world-wide FINGERS (WW FINGERS). As part of the collaboration, our Australian AU-ARROW trial will follow the general protocol of the FINGER trial, and will also be aligned with the U.S. arm of the study, US-POINTER, though will have minor cultural and dietary modifications to determine the validity of the intervention in an Australian setting. Method AU-ARROW is a randomised, single-blind 2-year clinical trial that will recruit 600 participants aged 60-79 satisfying specific inclusion/exclusion criteria, including normal cognition and one or more cardiovascular risk factors that place them at greater risk of cognitive decline. Participants will be distributed across two sites (a) Macquarie University Health Clinics, Sydney, NSW and (b) Sarich Neuroscience Research Institute, Edith Cowan University, Perth, WA, and will be randomised equally into either the innovative multi-modal intervention group or the study control group, who will receive general lifestyle advice and annual health check-ups, without treatment. Multi-modal intervention consists of aerobic exercise, resistance training and stretching; dietary advice with monitoring to encourage adherence to the MIND diet; cognitive training sessions via the Brain HQ computerised online training system; and medical monitoring and regular health education sessions. Heart rate trackers, diet and exercise log books, and the monitoring of Brain HQ sessions will all help with adherence. Primary outcome measure is improvement in global cognitive score, measured using neurocognitive tests identical to those in the US-POINTER protocol. Additional neurocognitive tests, physical function improvements, detailed diet monitoring and sleep monitoring will provide added data. The unique extra value of AU-ARROW trial consists of the testing for Alzheimer’s disease (AD) blood biomarkers in all participants; as well as the AD Aβ amyloid-specific ligand-PET imaging, brain MRI and retinal biomarker tests that half of the participants will undergo. These tests will provide comprehensive data which have the ultimate purpose of increasing knowledge of the preclinical stages of AD, and help not only to develop preclinical AD diagnostic tests but also efficacy of AU-ARROW’s intervention