Additive pressor effects of caffeine and stress in male medical students at risk for hypertension

The effects of caffeine on blood pressure (BP) and cortisol secretion were examined during elevated work stress in medical students at high versus low risk for hypertension. Among 31 male medical students who were regular con sumers of caffeine, 20 were considered at low risk for hypertension (negati ve parental history and all screening BP < 125/78 mm Hg) and 11 at high ris k based on epidemiologic criteria (positive parental history and average sc reening BPs between 125/78 and 139/89 mm Hg). Cortisol levels and ambulator y BP were measured with and without caffeine during two lectures (low work stress) and two exams (high work stress) in a randomized, double-blind, cro ssover trial. Caffeine consumption and exam stress increased cortisol secre tion in both groups (P < .05). BP increased with caffeine or exam stress in both groups, low versus high risk, respectively (Caffeine: + 5/4 vs + 3/3 mm Hg; Stress: + 4/1 vs + 7/3 mm Hg; P < .05). The combination of stress an d caffeine caused additive increases in BP (Low Risk + 9/5 mm Hg, High Risk + 10/6 mm Hg) such that 46% of high-risk participants had average systolic BP greater than or equal to 140 mm Hg. This combined effect of stress and caffeine on BP suggests that it may be beneficial for individuals at high r isk for hypertension to refrain from the use of caffeinated beverages, part icularly at times when work demands and attendant stressors are high. For t he same reasons, recent intake of caffeine should be controlled in patients undergoing BP measurement for the diagnosis of hypertension. (C) 2000 Amer ican Journal of Hypertension, Ltd.