Evidence from both hypertensive and normotensive individuals
indicate that elevated blood pressure is associated with decreased
pain sensitivity. The current study sought to experimentally
raise blood pressure using 250 mg caffeine, and investigate
its effects on the cold pressor pain experiences of 25 men and
25 women. In a placebo-controlled repeated-measures experiment,
caffeine increased systolic and diastolic blood pressure, as
well as producing more clearheaded and energetic feelings. Caffeine
produced higher pain threshold and pain tolerance levels compared
to placebo, and women had a lower tolerance to pain than men.
Finally, a significant association was found between
caffeine-related increase in systolic blood pressure and
caffeine-related increase in pain tolerance. Furthermore, this
association was the strongest in women. These results are discussed
in light of future directions for pain and hypertension research.