My doctor prescribed the blood thinner warfarin because I have atrial fibrillation. But I’ve heard that people who are over 70 shouldn’t take warfarin because it increases their risk of bleeding in the brain. Is that true? —M.G., Toronto

No. Warfarin (Coumadin and generic) is proved to lower the risk of stroke in people with atrial fibrillation, or heart rhythm disturbance, better than aspirin. While some earlier studies appeared to show that the blood thinner increased the risk of rare but life-threatening brain bleeding in the very old, newer research has found that whether a person takes warfarin or not, this bleeding risk increases with age, especially after age 85. That may stem from the agerelated increase in systolic blood pressure (the upper number), seniors’ increased tendency to fall, or both. Though warfarin doesn’t cause brain bleeding, it can increase the extent of that bleeding if it occurs. So those taking the drug should be especially careful to control hypertension and to safeguard their homes.