HYPOTHALAMIC-PITUITARY-ADRENOCORTICAL RESPONSES TO PSYCHOLOGICAL STRESS AND CAFFEINE IN MEN AT HIGH AND LOW-RISK FOR HYPERTENSION

Objective: This study examined pituitary-adrenocortical responses to d ietary doses of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coff ee), alone and combined with behavioral stress, in men at high risk ve rsus low risk for hypertension. A randomized, double-blind, caffeine-p lacebo crossover design was used. Method: Adrenocorticotropic hormone (ACTH) and cortisol levels in plasma were assessed at rest and in resp onse to 60-minutes of continuous work on a mental stressor (arithmetic ) and a psychomotor task (reaction time) on four test sessions held on separate days. Results: Tasks alone caused greater ACTH and cortisol increases in high risk men than in the low risk group. Caffeine alone elevated ACTH and cortisol in both groups, with more immediate respons es in the high risk group. Both groups showed significant ACTH and cor tisol responses to caffeine plus tasks, with the high risk group showi ng more persistent elevations. The high risk group also showed the hig hest levels of ACTH and cortisol after caffeine plus tasks. Conclusion s: These findings demonstrate for the first time the combined effects of caffeine plus stress on ACTH and demonstrate greater corticosteroid effects in hypertension-prone men. As such, they may have implication s for the dietary use of caffeine during periods of stress and in thos e at risk for hypertension.