Quantitatively assessing daily functional impairment in dementia by imaging cerebrovascular correlates.

BackgroundImpaired daily functioning can change day-to-day activities at the early stage of dementia, in varied association with cognitive decline and/or affective symptoms. Current clinical practice uses scales to assess daily functioning and can be prone to subject/proxy-related bias.ObjectiveTo investigate the yet unclear cerebrovascular correlate of daily activities and the usefulness of cerebral blood flow (CBF) as a quantitative marker of functional impairment.MethodsNinety patients with clinically diagnosed dementia and 30 healthy controls were prospectively recruited. Regional CBF within the frontotemporal-subcortical circuits was quantified by magnetic resonance imaging, compared between control and CBF-stratified patient groups, and then correlated with basic and instrumental activities of daily living.ResultsLower CBF was found to associate with impaired daily activities in most of the regions investigated after adjusted for the effect of age and Mini-Mental State Examination score. Analyses of partial correlation and receiver operating characteristic further revealed that impaired basic activities of daily living was best detected by the baseline CBF in the right middle temporal gyrus, with the area under the curve (AUC) = 0.860 (p < 0.001). Impaired instrumental activities of daily living was best detected by the CBF in the right superior temporal gyrus (AUC = 0.695, p < 0.001). The CBF in the two regions showed no significant detecting ability for anxiety and depression.ConclusionsWe identified the cerebrovascular correlates of daily functioning in line with the previously conceptualized role of frontotemporal-subcortical circuits, allowing quantitative assessment of daily activities with minimal confounding from affective symptoms.