Cortical Complexity Analyses and Their Cognitive Correlate in Alzheimer’s Disease and Frontotemporal Dementia

Publication: Journal of Alzheimer’s Disease

Nicolasa Nicastro, Maura Malpetti, Thomas Cope, William Richard Bevan-Jones, Elijah Mak, Luca Passamonti, James B. Rowe, John T. O’Brien

30 June 2020


The changes of cortical structure in Alzheimer’s disease (AD) and frontotemporal dementia (FTD) are usually described in terms of atrophy. However, neurodegenerative diseases may also affect the complexity of cortical shape, such as the fractal dimension of the brain surface.

In this study, the researchers assessed the regional patterns of cortical thickness and fractal dimension changes in a cross-sectional cohort of patients with AD and FTD.

In addition to the well-established pattern of cortical thinning encompassing temporoparietal regions in AD and frontotemporal areas in FTD, they observed reductions of fractal dimension encompassing cingulate areas and insula for both conditions, but specifically involving orbitofrontal cortex and paracentral gyrus for FTD (FDR p < 0.05). Correlational analyses between fractal dimension and cognition showed that these regions were particularly vulnerable with regards to memory and language impairment, especially in FTD.

While the present study demonstrates globally similar patterns of fractal dimension changes in AD and FTD, the researchers observed distinct cortical complexity correlates of cognitive domains impairment. Further studies are required to assess cortical complexity measures at earlier disease stages (e.g., in prodromal/asymptomatic carriers of FTD-related gene mutations) and determine whether fractal dimension represents a sensitive imaging marker for prevention and diagnostic strategies.

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