Phasic and tonic alerting in mild cognitive impairment: A preliminary study.

In this preliminary study we assessed the functioning of the different attentional networks in mild cognitive impairment (MCI) patients, taking as theoretical framework the Posner's cognitive neuroscience approach. Two groups of participants were tested in a single short experiment: 20 MCI patients (6 amnestic, 6 non-amnestic and 8 multiple-domain) and 18 healthy matched controls (HC). For attentional assessment we used a version of the Attention Network Test (the ANTI-V) that provided not only a score of the orienting, the executive, and the alerting networks and their interactions, but also an independent measure of vigilance (tonic alerting). The results showed that all subtypes of MCI patients exhibited a selective impairment in the tonic component of alerting, as indexed by a decrease in the d' sensitivity index, and their performance in executive network increased up to the HC group level when phasic alerting was provided by a warning tone. Our findings suggest that a core attentional deficit, especially the endogenous component of alerting, may significantly contribute to the behavioral and cognitive deficits associated with MCI.