When legal drugs are bad medicine

This is strange. For all the talk about the so-called dangers of medical marijuana, it's useful to remember that legal drugs are not without their own pitfalls.

Researchers have identified a strange side effect to a treatment for Parkinson's disease: excessive gambling. Some patients taking medications known as dopamine agonists developed the problem within six months of starting treatment, even though they had previously gambled only occasionally or never at all. "This is a striking effect," remarks J. Eric Ahlskog of the Mayo Clinic, a co-author of the new study. "Pathological gambling induced by a drug is really quite unusual."

Fortunately it only affects a small number of patients and can be easily remedied by changing medications.