A longitudinal observation of brain structure between AD and FTLD

Abstract

INTRODUCTION\nAlzheimer s disease (AD) and frontotemporal lobar degeneration (FTLD) are the leading causes of dementia. To better understand the disease development of cognitive function and anatomical structure in AD and FTLD, we analyzed the changes in brain volume by MRI and the psychological test results. Here, we report a dynamic observation of brain structure.\n\n\nMETHODS\nThirteen patients diagnosed with probable AD by the 2011 NIA-AA criteria and eight FTLD patients diagnosed by the FTLD criteria underwent MRI at baseline. All subjects were rescanned after 5 months to 3 years of follow-up. The anatomic changes on T1-weighted imaging of each subject were measured, and the separate changes in the two groups and the differences in the changes between AD and FTLD were analyzed.\n\n\nRESULTS\nIn AD patients, the anterior and posterior horns of the lateral ventricle and lateral fissure enlarged progressively (p\xa0<\xa00.001). The volume of the regions, including the medial and lateral temporal lobe, especially the parahippocampal gyrus, and the frontal lobe decreased significantly as the disease progressed (p\xa0<\xa00.001). Additionally, the volume of white matter in the frontal, parietal, temporal lobe and cerebellum decreased in a relatively symmetric pattern (p\xa0<\xa00.001). In FTLD patients, the anterior horn of the lateral ventricle, lateral fissure, cerebral longitudinal fissure, external space of the orbitofrontal cortex, and mesencephalon surrounding the cisterna were enlarged (p\xa0<\xa00.005), while regions including the left frontal lobe, anterior cingulate cortex, basal ganglia (especially the left basal ganglia), left lateral temporal lobe and inferior cerebellar vermis decreased as the disease progressed (p\xa0<\xa00.005). Regarding the differences between AD and FTLD, atrophy of the frontal lobe and bilateral basal ganglia was more significant in FTLD than in AD (p\xa0<\xa00.01). In addition, enlargements of the anterior horn of the lateral ventricle, left lateral fissure and interpeduncular cistern were more significant in FTLD patients than in AD patients (p <\xa00.01).\n\n\nCONCLUSIONS\nThese findings suggest that AD and FTLD have distinctly different atrophy patterns: AD patients show diffuse atrophy while FTLD patients show an asymmetrical focal atrophy pattern, which might explain the relatively better and longer preservation of daily living function in FTLD patients.