Neurofunctional Correlates of Activities of Daily Living in Patients with Posterior Cortical Atrophy

Background: Research on posterior cortical atrophy (PCA) has focused on cognitive decline, especially visual processing deficits. However, few studies have examined the impact of PCA on activities of daily living (ADL) and the neurofunctional and neuroanatomic bases of ADL. Objective: To identify brain regions associated with ADL in PCA patients. Methods: Atotal of 29 PCA patients, 35 typical Alzheimer's disease (tAD) patients, and 26 healthy volunteers were recruited. Each subject completed an ADL questionnaire that included basic and instrumental subscales (BADL and IADL, respectively), and underwent hybrid magnetic resonance imaging and F-18 fluorodeoxyglucose positron emission tomography. Voxel-wise regression multivariable analysis was conducted to identify specific brain regions associated with ADL. Results: General cognitive status was similar between PCA and tAD patients; however, the former had lower total ADL scores and BADL and IADL scores. All three scores were associated with hypometabolism in bilateral parietal lobes (especially bilateral superior parietal gyri) at the whole-brain level, PCA-related hypometabolism level, and PCA-specific hypometabolism level. A cluster that included the right superior parietal gyrus showed an ADL x group interaction effect that was correlated with the total ADL score in the PCA group (r = -0.6908, p = 9.3599e(-5)) but not in the tAD group (r = 0.1006, p = 0.5904). There was no significant association between gray matter density and ADL scores. Conclusion: Hypometabolism in bilateral superior parietal lobes contributes to a decline in ADL in patients with PCA and can potentially be targeted by noninvasive neuromodulatory interventions.