Attentional networks in normal aging and Alzheimer's disease.

By combining a flanker task and a cuing task into a single paradigm, the authors assessed the effects of orienting and alerting on conflict resolution and explored how normal aging and Alzheimer's disease (AD) modulate these attentional functions. Orienting failed to enhance conflict resolution; alerting was most beneficial for trials without conflict, as if acting on response criterion rather than on information processing. Alerting cues were most effective in the older groups--healthy aging and AD. Conflict resolution was impaired only in AD. Orienting remained unchanged across groups. These findings provide evidence of different life span developmental and clinical trajectories for each attentional network.