Perspective taking and its structural correlates in early Alzheimer's disease

Abstract

AbstractBackgroundThere is an increasing effort to find simple and reliable tests for the early diagnosis of Alzheimer´s disease (AD). Spatial orientation deficits are present early in AD and could thus serve as an early cognitive marker of the disease. We aimed to evaluate the potential of perspective taking tests to identify individuals with early AD and to determine associations between perspective taking and volumes of the selected brain regions affected in early AD.Method66 participants with amnestic mild cognitive impairment (aMCI) and positive AD‐biomarkers (aMCI due to AD, n=22), aMCI and negative biomarkers (aMCI AD‐negative, n=15), mild AD dementia (n=7) and cognitively normal (CN) older adults (n=22) underwent clinical and neuropsychological evaluation, MRI brain scan with automated volumetry, AD‐biomarker assessment and two perspective taking tasks: Standardized Road‐Map test of Direction Sense (RMTDS) and Perspective Taking/Spatial Orientation Test (PTSOT). In the RMTDS, the participants followed a pathway on a city map indicating a direction of turning at each intersection. The PTSOT included pictures of arrays of objects and participants indicated direction between selected objects.ResultThe aMCI due to AD and mild AD dementia groups had lower scores than the CN group (p<0.05) in the PTSOT. The aMCI due to AD group had a lower score compared to the CN group (p<0.05) in the RMTDS. There were no differences between the CN and aMCI AD‐negative groups in both tests. PTSOT scores correlated with volumes of the right inferior temporal gyrus and right and left precuneus.ConclusionThe perspective taking tests reliably detect spatial orientation impairment typical for early stages of AD. Worse performance in the PTSOT was associated with smaller volumes of the brain regions affected early in AD.