The risk of neurodegenerative disorders increases with age, due to reduced vascular nutrition and impaired neural
function. However, the interactions between cardiovascular dynamics and neural activity, and how these interactions
evolve in healthy aging, are not well understood. Here, the interactions are studied by assessment of the phase coherence
between spontaneous oscillations in cerebral oxygenation measured by fNIRS, the electrical activity of the brain measured
by EEG, and cardiovascular functions extracted from ECG and respiration effort, all simultaneously recorded. Signals
measured at rest in 21 younger participants (31.1±6.9 years) and 24 older participants (64.9±6.9 years) were analysed
by wavelet transform, wavelet phase coherence and ridge extraction for frequencies between 0.007 and 4 Hz. Coherence
between the neural and oxygenation oscillations at ∼0.1 Hz is significantly reduced in the older adults in 46/176 fNIRSEEG
probe combinations. This reduction in coherence cannot be accounted for in terms of reduced power, thus indicating
that neurovascular interactions change with age. The approach presented promises a noninvasive means of evaluating
the efficiency of the neurovascular unit in aging and disease.