Associations of neighborhood environment with brain imaging outcomes in the Australian Imaging, Biomarkers and Lifestyle cohort

Abstract

These findings indicate associations between neighborhood walkability and brain imaging measures (especially in APOE ε4 carriers) minimally attributable to physical activity.

The relationship between physical activity, apolipoprotein E ε4 carriage and brain health

“…Therefore, we could assume that there is more room for PA to counterbalance early neuropathological signs within this group. This is consistent with previous studies that demonstrate the effect of PA on brain pathology is most predominant among ε4 carriers (7,47,48).…”

“…in 60-80% of AD cases and is linked to a 3.2-fold increased AD risk in heterozygosis and up to 14.9fold increased AD risk in homozygosis (5). While most studies claim that PA-protective effects mainly manifest among ε4 carriers (6,7), others identified this same effect exists only in non-carriers (8,9), while other studies report benefits regardless of APOE ε4 allele carriage (10,11). This inconsistent literature is likely due to the use of varying study designs and outcome measures (i.e.…”

International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health

“…With regard to brain health, a previous study of 127 community dwellers was powered to detect associations between environmental attributes and 1.5-year changes in brain volume. 21 However, the participants were on average 10 years older than the iMAP sample. Also, significant 1.5year changes on 6 out of 12 cognitive function measures were detected in 685 cognitively intact participants with a mean age of 67 years (projected average age in iMAP: 65 years).…”

“…These samples sizes will, respectively, achieve 80% power to detect effect sizes equivalent to 1.9% and 0.6% of variance explained in longitudinal analyses. With regard to MRI brain imaging outcomes, our study indicated that environmental attributes may explain ~5% of the variance in MRI brain volumetric measures, 21 requiring 152 participants to achieve 80% power in site-specific cross-sectional regression analyses. With a conservative 20% drop-out rate 49 and 200 participants at baseline, the final sample size of 160 participants per site and 560 in total will, respectively, be able to detect effect sizes equivalent to 5.0% and 1.4% of variance explained in longitudinal analyses.…”

“…Preliminary support for the importance of urban design for brain and cognitive health comes from a few recent studies, which found mixed land use, access to various types of destinations and/or access to public transport to be predictive of better cognitive health 19 20 and brain health. 21 Yet, the findings have not been consistent. Unexpected negative or curvilinear associations between measures of destination accessibility and cognitive function have also been reported.…”