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Caffeine may potentiate adrenocortical stress responses in hypertension-prone men
W R Lovallo1, G A Pincomb, B H Sung
1Behavioral Sciences Laboratories, VA Medical Center, Oklahoma City, OK 73104.
Insights
Caffeine significantly elevates blood pressure and cortisol levels in men at high risk for hypertension, especially during a challenging task. Low-risk men experienced different cortisol responses to caffeine and task stress.
Area of Science:
- Cardiovascular Physiology
- Endocrinology
- Psychopharmacology
Background:
- Essential hypertension risk is influenced by genetics and baseline blood pressure.
- Caffeine's physiological effects, including on blood pressure and stress hormones, warrant investigation in relation to hypertension risk.
Purpose of the Study:
- To investigate the differential effects of caffeine on blood pressure and cortisol levels in men with low versus high risk for essential hypertension.
- To assess the combined impact of caffeine and a psychomotor task on cardiovascular and endocrine responses.
Main Methods:
- Thirty-four healthy men (ages 21-35) were categorized as high-risk or low-risk for hypertension.
- Participants underwent a protocol involving rest, placebo or caffeine (3.3 mg/kg) administration, and a simple reaction time task.
- Blood pressure was monitored continuously, and blood samples were collected at baseline, post-drug, during task, and recovery periods.
Main Results:
- Caffeine combined with the psychomotor task induced the highest blood pressures in high-risk individuals.
- High-risk men exhibited sustained cortisol levels during rest after caffeine, unlike low-risk men who showed a decline.
- Caffeine consumption led to significant cortisol increases during and after the task in high-risk subjects.
Conclusions:
- Caffeine exacerbates blood pressure responses to stress in individuals predisposed to hypertension.
- Differential cortisol regulation by caffeine exists between high-risk and low-risk individuals, particularly under stress.
- These findings highlight caffeine's potential role in modulating cardiovascular and stress hormone responses in hypertension development.
Abstract:
The effect of caffeine on blood cortisol levels and blood pressures was examined during rest and in response to a challenging psychomotor task in men with a low versus high risk of essential hypertension. Thirty-four healthy men ages 21-35 years were selected such that 17 were at high risk for hypertension (positive parental history and screening blood pressures of 135/85-155/95 mm Hg) and 17 were at low risk (negative parental history and no pressures above 132/84 mm Hg). Testing consisted of quiet rest (20 minutes); oral placebo (grapefruit juice) or caffeine administration (3.3 mg/kg in grapefruit juice); rest during a postdrug absorption period (40 minutes); work on an unsignalled simple reaction time task (15 minutes); and quiet rest (20 minutes). Blood pressures were recorded at 2-minute intervals, and blood samples were withdrawn via an indwelling catheter at the end of the baseline, drug absorption, task, and recovery periods. The combination of task plus caffeine produced the highest blood pressures in men at risk for hypertension. Cortisol levels were found to be sustained during rest in members of the high risk group after they had consumed caffeine, whereas members of the low risk group showed a modest decline. The high risk subjects also showed a significant rise in cortisol during (+3.7 micrograms/dl) and after (+4.0 micrograms/dl) work on the reaction time task after caffeine consumption.(ABSTRACT TRUNCATED AT 250 WORDS)