If depression is sadness taken to extreme, can extreme happiness also be considered a mental illness?

Is exercise beneficial for depressed people?

What is the length of time for which the patient needs to present a certain set of symptomatology for diagnosing depression?

Once you are diagnosed with clinical depression, are you more at risk for a lifelong illness and long-term management?

What is the relationship between marijuana use and bipolar disorder?

Is there any difference in the prevalence of bipolar disorder among different ethnicities?