The mechanical state of intracranial tissues in elderly subjects studied by imaging CSF and brain pulsations.

The biomechanical properties of intracranial tissues influence the mechanical coupling of brain and CSF oscillations to the driving vascular pulsations. Dynamic phase contrast MRI was used to measure the transfer functions that characterize these couplings in normal elderly subjects and patients with Alzheimer's disease. The transfer functions of both groups were significantly different from the previously reported transfer functions of normal young subjects. The data show that vascular pulsations tend to cause greater spinal cord movements and smaller CSF oscillations in the older subjects than in the younger ones. These results are likely to be due to age-related changes in the mechanical state of intracranial tissues.