Functional correlates of instrumental activities of daily living in mild Alzheimer's disease.

Instrumental activities of daily living (IADL) includes the integration of task-initiation, -planning, and -performance. Little is known on the cerebral perfusion correlates of these subcomponents of IADL in Alzheimer's disease (AD). In 121 AD patients, cerebral perfusion, using single-photon emission computed tomography, in 13 bilateral regions of interest (ROI) and the perfusion correlates of IADL subcomponents, rated on the Disability Assessment in Dementia scale, were explored. Significant correlations were observed between IADL initiation and multiple bilateral prefrontal-striatal-anterior cingulate ROI (p < 0.01), IADL planning and right occipital ROI (p < 0.05), and IADL performance and right parietal ROI (p < 0.05). Multiple regression, accounting for age, cognitive impairment, and depression severity, revealed significant relationship between right basal ganglia perfusion and IADL-initiation (R = 0.6, R(2) = 0.39, F(4,117) = 17.8, SE = 1.56; p < 0.001) and right occipital perfusion and IADL-planning (R = 0.6, R(2) = 0.34, F(4,117) = 19.5, SE = 1.47; p < 0.001). In AD, perfusion correlates of these subcomponents may be linked to the heterogenous cognitive processes involved in IADL.