Comparison of white matter hyperintensities between Latin American and American individuals with Alzheimer’s disease and cognitively normal older adults

Abstract

AbstractBackgroundWhite matter hyperintensities (WMH) are Flair signal abnormalities frequently seen in periventricular and subcortical brain regions in the elderly. They are presumed to be, at least in part, a sign of cardiovascular disease (CVD). WMHs are associated with stroke, cognitive decline, and dementia. Given that most of the literature on dementia comes from high‐income countries, little is known about dementia in Latin American countries (LAC), which have an increased risk of dementia and CVD due to unique demographic, socioeconomic, cultural and ethnic factors. Our study aims to characterize the effects of white matter hyperintensities (WMH) in patients with AD within LAC and to compare these findings with a sample from the USA.MethodA total of 491 latin american subjects (235 cognitively normal (CN), 256 AD) and 271 american subjects (165 CN, 106 AD), underwent a brain MRI. WMH were extracted from T2‐FLAIR images using the Lesion Segmentation Toolbox and were divided into periventricular (pWMH) or deep (dWMH) depending on their distance from the ventricles. Linear mixed‐effects were used to model the volumes of WMH as a function of age, gender, years of education, intracranial volume, average cortical thickness, and region (LAC or USA).ResultAD groups from both regions showed larger total, dWMH and pWMH volumes compared to HC. Higher pWMH from AD and HC was associated with age, female sex and inversely associated with years of education. On the other hand, the increase in dWMH was found to be associated with female sex for the HC group and with age for AD. Cortical thinning was associated with an increase in total, subcortical and periventricular WMH for both groups. No statistically significant association was found between the region (USA or LAC) and WMH.ConclusionAD showed higher WMH compared to HC. Our findings suggest that pWMH and dWMH have different clinical correlates. No associations between region and WMH load or distribution were found. Future studies need to elucidate if there is an increase in other signs of CVD (such as cerebral microbleeds, brain lacunae, enlarged perivascular spaces) in Latin America and if they are linked to cognition and social determinants of health.