Performance-Based Functional Status Predicts Diffuse Cortical Atrophy in Alzheimer's Disease

Objectives: We aimed to compare performance-based functional ability and cognitive screening performance to determine the cortical thickness relationship in cognitively unimpaired (CN) elders, mild cognitive impairment (MCI) and dementia patients, as well as to compare performance-based and proxy-evaluated functional ability and to determine its cerebral white and gray matter correlates. Methods: In total, 22 CN, 32 MCI, and 21 dementia patients were included in this study. They underwent clinical, cognitive, and Magnetic Resonance Imaging (MRI) assessment. Individuals were evaluated with the Mini-Mental State Examination (MMSE), the Rey Auditory Verbal Learning test (RAVLT), the Activities of Daily Living Questionnaire (ADL-Q) and the Direct Assessment of Functional Status-Revised (DAFS-R). Results: Higher ADL-Q scores were significantly associated with lower cortical thickness (bilateral temporoparietal regions, including the inferior temporal lobes and precuneus), p < 0.05. The DAFS-R scale showed a relationship with greater cortical thickness across extensive regions of the bilateral frontal, parietal, and temporal cortices (p < 0.05). MMSE presented a more focal association, primarily in canonical memory-related areas, including the medial and lateral temporal lobes and inferior parietal regions (p < 0.05). Conclusions: Functional independence measured by ADL-Q was associated with frontal and parietal cortical thickness, while DAFS-R scores demonstrated a more diffuse evaluation of cortical atrophy. Additionally, performance-based functional abilities according to the DAFS-R appear to be a stronger marker of cortical thickness than ADL-Q and MMSE.