Is there a specific pattern of attention deficit in mild cognitive impairment with subcortical vascular features? Evidence from the Attention Network Test.

BACKGROUND: Mild cognitive impairment (MCI) is an intermediate state between normal aging and early dementia. Some MCI patients show white matter hyperintensities in magnetic resonance imaging, revealing subcortical vascular damage (SVD). This study aimed to evaluate potential attention deficits not previously described in these patients. Specifically, we evaluated attention network functioning in MCI on the basis of Posner's cognitive neuroscience model, which considers attention as a set of networks: alerting, orienting and executive control. METHODS: Three groups of participants were tested: 19 MCI patients with SVD (svMCI), 15 MCI patients free from SVD (nvMCI) and 19 healthy controls (HC). We used a task in which the three attention networks and their interactions can be assessed simultaneously, the Attention Network Test (ANT). RESULTS: The svMCI group showed smaller orienting effect compared with the nvMCI and HC groups. In contrast to the HC and nvMCI groups, svMCI patients did not show improvement in the executive network from the valid visual cue. CONCLUSIONS: svMCI patients show a deficit in orienting attention networks. This deficit could be related to an effect of SVD on the cholinergic system because acetylcholine is implicated in the modulation of covert orienting responses of attention.

Attention network functioning in patients with dementia with Lewy bodies and Alzheimer's disease.

BACKGROUND: Attention deficits are at the core of the defects in neuropsychological performance which define both dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Most studies have used separate tasks to test different attention abilities in patients with these diagnoses, precluding the assessment of any interaction among the different attention components. METHODS: We used a version of the Attention Network Test in which the alerting, orienting and executive attention networks, along with their interactions, could be assessed with a single task. Three groups of participants were tested: DLB patients (n = 13), AD patients (n = 18) and healthy controls (n = 18). RESULTS: The alerting signal improved orienting attention and increased the conflict effect in the healthy controls, but they had no effect on these networks in the AD patients. The DLB patients only showed preserved orienting and conflict effects when the alerting signal was present, indicating that there was regulation of the orienting and executive attention networks by the alerting signal. CONCLUSIONS: The most important differences among the 3 groups were observed in the attention network interactions, where alerting played a more relevant role in the DLB than in the AD patients. Under alerting states, the DLB patients showed evidence of certain regulation in the orienting and executive attention networks.