Hemodynamic changes in the prefrontal cortex during working memory in essential hypertension.

Behavioral performance and hemodynamic changes in the prefrontal cortex (PFC) represent cerebrovascular reserve and may indicate functional deficits related to essential hypertension. Fifteen stage 1 hypertensive and normotensive males (19-55 years) were compared on four tests of working memory (digit span and auditory consonant trigrams), and accompanying hemodynamic changes measured by functional near infrared spectroscopy (fNIRS). With participants blindfolded, the four tests were randomized while fNIRS was used to monitor bilateral PFC changes in oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), total hemoglobin (tHb), and hemoglobin difference. The hypertensive group demonstrated significant impairment in performance on the working memory tests with a trend of decreased efficiency performance scores (tests score/O2Hb and tHb changes). Significant correlations were noted in the hypertensive group between test performance and changes in O2Hb and tHb in both the left and right PFC. These findings suggest that fNIRS combined with cognitive testing may provide important measures of cerebrovascular reserve in essential hypertension.