Depression Depression is a mood disorder that involves a persistent feeling of sadness and loss of interest. It is different from the mood fluctuations that people regularly experience as a part of life. Signs and symptoms m The symptoms of depression can include: A depressed mood Reduced interest or pleasure in activities once enjoyed Changes in appetite Unintentional weight loss or gain Sleeping too much or too little Agitation, restlessness, and pacing up and down Slowed movement and speech Fatigue or loss of energy Causes The medical community does not fully understand the causes of depression. There are many possible causes, and sometimes, various factors combine to trigger symptoms. Factors that are likely to play a role include: Genetic features Changes in the brain’s neurotransmitter levels Environmental factors Psychological and social factors Additional conditions, such as bipolar disorder Conditions that can get worse due ...