Geospatial environmental complexity, spatial brain volume, and spatial behavior across the Alzheimer's disease spectrum.

INTRODUCTION

Understanding impact of environmental properties on Alzheimer's disease (AD) is paramount. Spatial complexity of one's routinely navigated environment is an important but understudied factor.

METHODS

A total of 660 older adults from National Alzheimer's Coordinating Center (NACC) dataset were geolocated and environmental complexity index derived from geospatial network landmarks and points-of-interest. Latent models tested mediation of spatial navigation-relevant brain volumes and diagnosis (cognitively-healthy, mild cognitive impairment [MCI], AD) on effect of environmental complexity on spatial behavior.

RESULTS

Greater environmental complexity was selectively associated with larger allocentric (but not egocentric) navigation-related brain volumes, lesser diagnosis of MCI and AD, and better spatial behavioral performance, through indirect hierarchical mediation.

DISCUSSION

Findings support hypothesis that spatially complex environments positively impact navigation neural circuitry and spatial behavior function. Given the vulnerability of these very circuits to AD pathology, residing in spatially complex environments may be one factor to help stave off the brain atrophy that accompanies spatial navigation deficits across the AD spectrum.