Depression (from the Latin depressio, meaning 'oppression', 'shrinkage' or 'dejection') is a mood disorder, characterized by feelings of despondency, unhappiness and guilt, with difficulty enjoying everyday life. It is usually accompanied to a greater or lesser extent by anxiety.
The origin of depression is multifactorial, influencing biological, genetic and psychosocial factors. Environmental factors that increase the risk of depression are the death of a loved one, a move, family conflicts, surgery, psychosocial stress, food intolerance, physical inactivity, obesity, smoking or drug addiction. Among the psychosocial factors, stress and certain negative feelings stand out (a sentimental disappointment, contemplation or experience of an accident, murder or tragedy, bad news, social context, aspects of personality, a near-death experience) or an inadequate preparation of A challenge.


The symptoms mainly affect the emotional sphere and consist of sadness, depression, irritability, a feeling of discomfort and helplessness. Although this is common, cognitive, volitional or even somatic conditions may also appear. The person suffering from depression may not experience sadness, but rather suffer a loss of interest and inability to enjoy daily recreational activities, demotivation and psychomotor slowing.


Treatment is based on psychotherapy associated with antidepressant drugs. The most used antidepressants are SSRIs (Serotonin Reuptake Inhibitors), since it is believed that there is a deficit in brain serotonin. Treatment with antidepressants is the only one that has demonstrated significant effectiveness in major and psychotic depression, either alone or in combination with psychotherapy. For mild depression, psychotherapy may be more effective than pharmacological treatment.​

No differences have been found between the effectiveness of different types of antidepressants. The antidepressant effect takes about two weeks to appear, gradually increasing to its peak of maximum effectiveness around two months. Pharmacological treatment must be continued for six to twelve months to avoid the risk of relapses, although the full effect can be achieved one month after starting treatment.