Anxiety can be normal in stressful situations such as public speaking or taking a test. Anxiety is only an indicator of underlying disease when feelings become excessive, all-consuming, and interfere with daily living.
The persistent feeling of sadness or loss of interest that characterizes major depression can lead to a range of behavioral and physical symptoms. These may include changes in sleep, appetite, energy level, concentration, daily behavior, or self-esteem. Depression can also be associated with thoughts of suicide.