Longitudinal transcranial Doppler hemodynamics in older adults with and without mild cognitive impairment

Abstract

Cerebrovascular hemodynamics are increasingly implicated in cognitive aging and mild cognitive impairment (MCI). Transcranial Doppler (TCD) ultrasonography enables noninvasive assessment of intracranial blood flow dynamics. However, longitudinal data in older adults with and without MCI remain limited. This study aimed to longitudinally characterize cerebral hemodynamic and cognitive changes in elderly adults with and without MCI.

This prospective cohort study included adults aged ≥60 years enrolled through the CIMVAC registry and evaluated at a dedicated neurological assessment center. Participants underwent standardized clinical evaluation, neuropsychological testing, carotid duplex ultrasonography, and TCD at baseline and two-year follow-up. TCD parameters included peak systolic, end-diastolic, and mean flow velocities, pulsatility index, and resistance index in the middle cerebral arteries, with bilateral values averaged per participant.

Ninety-nine participants completed 2-years follow-up. Baseline extracranial atherosclerotic burden was low, with carotid plaque identified in 16.7% of vessels. Over 2 years, plaque prevalence and intima–media thickness increased significantly. TCD demonstrated significant longitudinal increases in pulsatility and resistance indices (both p < 0.001), while flow velocities remained unchanged. Cognitive performance declined modestly, with reductions in MMSE and IADLs scores and increased depressive symptoms. Although patients with MCI exhibited lower cognitive scores and lower baseline flow velocities, no consistent differences in Doppler-derived parameters were observed between MCI subgroups at baseline or follow-up.

In elderly adults, TCD primarily reflects age-related changes in cerebrovascular resistance but does not reliably distinguish MCI from normal cognition. Nonetheless, TCD may serve as a complementary, low-cost tool for longitudinal cerebrovascular monitoring, particularly in resource-limited settings.