Caffeine, extended stress, and blood pressure in borderline hypertensive men

Caffeine increases blood pressure (BP), and its pressor effects are larger in borderline hypertensive (BH) men than in controls. This article extends findings of larger caffeine effects on BP at rest and to brief mental stress in BH to a new analysis of caffeine and prolonged mental stress in BH. In a double-blind, crossover study, 24 male BH (140/90 mmHg < BP < 160/95 mmHg) and 23 normotensive controls who were habitual caffeine consumers (NT; BP < 135/85 mmHg; negative parental history) worked on alternating mental stressors for 35 min after placebo or caffeine (3.3 mg/kg). Caffeine raised systolic blood pressure (SBP) and diastolic blood pressure (DBP) alone and during the extended tasks (all ps < .00001/.00001). BH had larger SBP and DBP increases over all postcaffeine periods (ps < .04/04) and larger DBP rises to the extended tasks after caffeine (p = .007). These combined effects led to undesirably high BPs (> 140/82 mmHg) relative to controls (< 130/75) during the 100 min after caffeine intake. Caffeine taken by BH at times of extended behavioral stress may elevate BP to a clinically meaningful degree.