Visual attention deficits in Alzheimer's disease: Relationship to HMPAO SPECT cortical hypoperfusion

► AD patients were slower to reorient their attention to an uncued location. ► AD patients showed a greater cost for switching attention to invalid left targets. ► Right superior parietal hypoperfusion uniquely accounted for this validity effect. ► Bilateral parietal pathology can lead to attentional deficits as with focal lesions. ► Orienting deficit in AD patients resembles that from focal lesion, but less severe.