Hostility and caffeine: cardiovascular effects during stress and recovery

Both hostility and caffeine are frequently cited as potential factors in coronary heart disease (CHD). The present study examined the independent and interactive effects of these important variables on cardiovascular functioning. The Cook–Medley Scale was used to select 24 high and 24 low hostile subjects, who received caffeine (400 mg) or a placebo (lactose) in a double-blind design. All completed mental arithmetic (MA) and anagram stress tasks during which they experienced periods of verbal harassment and non-harassment. Blood pressure and heart rate were recorded. The combination of high hostility and harassment increased diastolic blood pressure (DBP) and maintained elevated levels of mean arterial pressure (MAP) during task periods, while reducing DBP recovery during rest periods. Caffeine increased systolic blood pressure (SBP) and interacted with harassment to create an inverted-U effect, reducing blood pressure. Finally, hostility and caffeine interacted to maintain elevated levels of DBP during recovery periods. These results support the dual-interactional theory of personality and behavior, which suggests an interaction of genetic and environmental factors and of dispositional and situational factors.