November 5, 2010 — A cup of coffee can heighten the risk for ischemic stroke, particularly among infrequent drinkers, report researchers. Their study provides new information that may be useful in stroke prevention and is in line with what is already known about the physiologic effects of coffee.
Investigators led by Elizabeth Mostofsky, MPH, from Harvard Medical School in Boston, Massachusetts, found a 2-fold increased stroke risk in the hour after drinking a cup of coffee. The increased risk returned to baseline within a 2-hour window, which investigators say strengthens the possibility of a causal relationship.
The work appears in the November 2 issue of Neurology.
In this new multicenter crossover study, researchers interviewed 390 people with ischemic stroke. They compared each person's coffee intake the hour before stroke symptoms to his or her usual consumption.
Most people, 78%, said they drank coffee the prior year. More than half of these had a cup of coffee within 24 hours of stroke. Close to 9% of patients had coffee within 1 hour of stroke onset.
Although an increase in stroke risk was seen with coffee, there was no apparent increase in risk in the hour after a cup of caffeinated tea or cola.
The association between ischemic stroke in the hour after coffee consumption was only apparent among those consuming 1 cup or less per day and not for those who drank coffee more regularly (P for trend = .002). Relative risks remained similar when researchers restricted the sample to those who were not simultaneously exposed to other potential triggers, and the results remained significant after stratifying by time of day.
The peak plasma concentration of caffeine is usually less than 2 hours and has several systemic effects, including rapidly increasing epinephrine release, blood pressure, and insulin sensitivity, they explain. "Caffeine has both systemic and cerebral vasoconstrictive effects."