Long-term use of the painkiller ibuprofen may reduce the risk of dementia, a large-scale study suggests. Researchers studied 250,000 veterans and found that those who used ibuprofen regularly for more than five years were 40 percent less likely to develop Alzheimer's. But experts say that not all non-steroidal anti-inflammatory meds reduce the risk of dementia, and that people should not start taking ibuprofen regularly without talking to their doctor.