Longitudinal cortical thinning is associated with cognitive decline in MCI and Alzheimer's disease in the Korean population.

Und: Alzheimer's disease (AD) is characterized by cognitive dysfunction likely secondary to progressive neurodegeneration in the brain. However, to what extent regional cortical thickness (CT) changes are related to cognitive decline in the Asian population remains unclear. Method: We measured CT using Freesurfer v6 from T1‐weighted magnetic resonance imaging (MRI) data in 603 Korean participants, including 71 young and 288 old cognitively unimpaired (CU young and CU old), 149 with mild cognitive impairment (MCI), and 92 AD from the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer's disease (KBASE). Cognitive function of each participant was quantified by the MMSE. MRI and cognitive data were acquired at baseline (n = 603) and a 2‐year follow‐up visit (n = 380). Linear mixed‐effect models were used to estimate diagnosis group, time, and group‐by‐time interaction effects on CT measurements, with age, sex, and education as covariates. Pearson's correlations between CT measurements and MMSE total score were computed, corrected for multiple comparisons by false discovery rate (FDR). Result: At baseline, CU old participants had lower CT values than CU young participants in the inferior parietal cortex and frontal and parietal regions. In comparison with CU old participants, MCI and AD showed widespread lower CT values, more pronounced in the medial temporal lobe (i.e., the entorhinal cortex and parahippocampal gyrus), inferior temporal cortex, medial prefrontal cortex, and medial parietal cortex (i.e., the posterior cingulate cortex and precuneus), with AD lower than MCI in these regions. These regions also showed the most longitudinal atrophy in both AD and MCI over 2 years. AD patients showed faster and more widespread atrophy patterns than MCI and CU old participants. We identified significant (PFDR<0.05) positive linear correlations between cognitive decline and regional CT measurements, particularly in regions showing significant cortical thinning across time. Conclusion: In this study, we replicated the typical cross‐sectional and longitudinal brain atrophy patterns, and relationships with cognitive decline in an Asian cohort. Our findings support the generalizability of atrophy patterns in MCI and AD, suggesting common neurobiological mechanisms underlying AD symptoms across different ethnoracial populations. [ABSTRACT FROM AUTHOR]