Selective attention in a reaching task: Effect of normal aging and Alzheimer's disease

This study examined the ability of young adults, older adults, and older adults suffering from Alzheimer's disease (AD) to perform a selective reaching task. Normal aging did not increase interference caused by distracters. In contrast, patients with AD showed massively increased effects of distracter interference. AD patients showed a high probability of making responses to distracter items. The proportion of these incorrect responses was related to the inability to use inhibitory processes, which increased with the severity of AD. Responses to distracters occurred despite the fact that patients could discriminate targets and distracters and knew that their responses to distracters were in error. These data suggest that AD patients are impaired in their ability to inhibit incorrect responses.