Tissue oxygen saturation and pulsatility index as markers for amnestic mild cognitive impairment: NIRS and TCD study

ObjectiveTo evaluate the utility of near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD) parameters as potential markers for amnestic mild cognitive impairment (aMCI).MethodsBy means of NIRS and TCD, noninvasive and inexpensive technologies, we studied 21 patients with aMCI (10 M and 11 F, 70.2 ± 7.3 years) and 10 age matched healthy controls.ResultsBy means of NIRS, we found a significant mean decrease of tissue oxygen saturation of cortex microcirculation (TOI), – 27%, p < 0.0005, on the temporal–parietal cortex of both side compared to the controls. By means of TCD, we found a significant mean increase of pulsatility index (PI), p < 0.0007, of middle cerebral artery (MCA) of both side compared to the controls. Cerebrovascular risk factors were present in 81% of the aMCI patients.ConclusionsOur study reveals that the TOI reduction on the temporal-parietal cortex of both side and the increase of PI in both MCA are associated with a clinical diagnosis of aMCI patients.SignificanceThe reduction of TOI may be considered a new marker for aMCI, especially when combined with the increase of PI in MCA.

► New application of near-infrared spectroscopy to study amnestic mild cognitive impairment. ► The TOI reduction on the temporal-parietal cortex of both side and increase of pulsatility index in both MCA are associated with a clinical diagnosis of amnestic mild cognitive impairment. ► The reduction of cerebral tissue oxygen saturation, especially when combined with the increase of pulsatility index, may be considered a new marker for amnestic mild cognitive impairment.