A continuous feeling of sadness could be just a dark mood, or it could be persistent depressive disorder that lasts for a long period of time. Persistent Depressive Disorder, or PDD, is not as severe ...

According to the National Institutes of Health, approximately 500,000 people in the U.S. have been diagnosed with Parkinson’s disease (PD), and that number is expected to double by 2040. Many of these ...

DEAR MAYO CLINIC: How is seasonal affective disorder diagnosed and treated? Seasonal affective disorder (SAD) is a type of depression that occurs during the winter months. Although exactly what causes ...