Cognitive Impairment and Cerebral Haemodynamics in Individuals with Symptomatic Peripheral Artery Disease

Peripheral artery disease (PAD) is highly prevalent in older adults. PAD is associated with cognitive impairment; however the underlying mechanisms are unclear. The brain's metabolic needs rapidly change in response to neuronal activity requiring adjustment of regional cerebral blood flow, termed neurovascular coupling (NVC). The microvascular endothelium contributes to NVC responses. Patients with PAD have endothelial dysfunction that may extend to the cerebral circulation, impairing NVC and cognitive function. The present study examined NVC responses to cognitive stimulation using Transcranial Doppler Ultrasonography (TCD) in older adults with PAD. Participants underwent bilateral TCD in the middle cerebral arteries during four recordings; baseline and tasks from Addenbrooke's-III Cognitive Examination and Digit Span. Mean absolute change in cerebral blood velocity (CBv) was measured at two time points (25-30s; 30-40s) from a 20s baseline. Nineteen patients with intermittent claudication and 20 age-matched controls (mean: 68.4 [8.1] years; female: 12) were included. CBv increased on all cognitive tasks, however no significant differences were observed between patients (range: 0.9-7.4 cm/s) and controls (range: 1.1-6.9 cm/s). Patients with PAD had significantly poorer working memory and global cognitive function. Older adults with PAD had similar NVC responses to age-matched controls. The lack of differences may be due to the low prevalence of cognitive impairment, disease severity, small sample size, or the relatively simple cognitive paradigms. Future studies examining NVC in patients with PAD during tasks with higher cognitive load, and in more advanced disease stages, are needed to further understand whether impaired NVC contributes to PAD-related cognitive impairment.