depression (1000 words) risk factorsmood disorderdepression includetypes of depressivefeeling sadunited statesmental illnessestreat depressionmajor depressive episodemental disordersst john s wortbipolar disordernational institute of mental healthmedical conditionshealth professionalside effectspostpartum depressionsymptoms of depressionpeople with depressionseasonal affective disorder