(CBS) - Too much strenuous exercise can be bad for your heart. Two European studies found increased risks of heart attacks, strokes, and irregular heart rhythms in people who engaged in prolonged, high-intensity exercise. But don't quit the gym. The authors of both studies stress regular exercise is still necessary for long-term health. _______________________________________________________________________________________________________________________ (CBS) - A common antidepressant might slow Alzheimer's disease. That's according to a new study at Washington University and the University of Pennsylvania. It finds the antidepressant Citalopram reduces brain plaques - which are linked to memory loss and other impairments from Alzheimer's . But researchers warn it's way too early to recommend people take antidepressants to prevent Alzheimer's. _______________________________________________________________________________________________________________________ (CBS) - And, a new Canadian study suggests some patients who are hospitalized over the weekend have a higher risk of death - regardless of when they were admitted. Researchers have long known about the so-called "weekend effect" for patients who enter the hospital on a weekend. But this new study is the first to show that risk exists even for patients who were admitted earlier in the week - but stayed through the weekend.