Background: Transcranial Doppler Ultrasonography (TCD) can be utilised to measure
the tight coupling of cerebral blood flow velocity (CBFv) in response to cognitive demand by task
activation, termed neurovascular coupling.
Aims: To investigate the differences in neurovascular coupling between healthy older (>50 years)
and younger (18-49 years) adults in response to cognitive testing.
Methods: Fifty-four older (n=25) and younger (n=29) adults underwent continuous bilateral TCD,
beat-to-beat blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO2
(ETCO2; capnography) monitoring. After a 5-min baseline period, memory (M1-4: recalling three
learned words, learning a name and address, recalling US presidents and UK prime ministers, and
recalling the previously learned name and address) and visuospatial (V1-4: drawing a cube and infinity
diagram, drawing a clock face, counting dots, and recognising obscured letters) tasks from
the Addenbrooke's Cognitive Examination (ACE-III) were performed. Data are mean (standard deviation).
Results: In the memory paradigms, the peak percentage change in CBFv differed significantly between
younger and older groups only in the dominant hemisphere during the M1 task, (2.17
(9.16)% vs. 8.38 (9.27)%, respectively, p=0.017). In the visuospatial paradigm, there were also significant
differences in peak percentage change in CBFv between younger and older groups in the
V1 (5.87 (8.32)% vs. 11.89 (6.60)%, p=0.005) and V2 tasks (6.30 (8.72)% vs. 11.30 (7.77)%,
Conclusion: Healthy older adults demonstrate augmented cerebrovascular physiology in response
to cognitive challenge compared to younger adults. The impact of abnormal ageing on cerebrovascular
physiology, for example, related to cognitively impaired states, requires further investigation.