Frontoparietal functional connectivity underlies top-down attention in mild cognitive impairment

Patients with amnestic mild cognitive impairment frequently show attention problems such as reduced top-down control, the ability to ignore task-irrelevant information. It is unclear whether this reduction corresponds with decreased brain connectivity. We aimed to determine whether and how differences in functional connectivity, or the correlated activity between brain areas, explain differences in top-down control in amnestic mild cognitive impairment. We conducted a case-control study with 26 patients with amnestic mild cognitive impairment (58-91 years; 10 women) and 29 age-matched healthy older adults (60-79 years; 9 women). All patients and control participants underwent neuropsychological assessment to confirm diagnosis and healthy cognitive status, respectively. We used resting-state functional magnetic resonance imaging at 3T to analyse functional connectivity. Top-down control was estimated with a 'theory of visual attention'-based verbal partial-report task (parameter α ; higher α indicates poorer control). We identified visual and attention-relevant functional brain networks and tested for differences between patients and controls while controlling for age and gender. Compared with healthy control participants, patients with amnestic mild cognitive impairment showed lower functional connectivity in the left frontoparietal attention network and in one visual network and worse top-down control α (t(37.43) = -2.24, p = 0.031). The reduced connectivity in the frontoparietal network, but not the visual network, significantly correlated with top-down control α across all participants (ρ = -0.33, p = 0.003) and in the patient group (ρ = -0.48, p = 0.014). Moreover, connectivity in the frontoparietal network mediated the relationship between amnestic mild cognitive impairment and top-down control α. These results link lower frontoparietal connectivity to worse attentional control in patients with amnestic mild cognitive impairment. Worse control reflects inefficient attentional selection and increasing distraction by irrelevant information during perceptual processing and encoding into working memory. Overall, this implicates a role for the frontoparietal network in maintaining cognitive control or, more generally, supporting cognitive functioning in older adults with emerging cognitive impairment.