Anti-depressant

Antidepressants are drugs used for the treatment of major depressive disorder and other conditions, including dysthymia, anxiety disorders, obsessive compulsive disorder, eating disorders, chronic pain, neuropathic pain and, in some cases, dysmenorrhoea, snoring, migraine, attention-deficit hyperactivity disorder (ADHD), addiction, dependence, and sleep disorders. They may be prescribed alone or in combination with other medications.

The most important classes of antidepressants are the selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), reversible monoamine oxidase A inhibitors (rMAO-A inhibitors), tetracyclic antidepressants (TeCAs), and noradrenergic and specific serotonergic antidepressant (NaSSAs).St John's wort is also used in the treatment of depression.

One theory regarding the cause of depression is that it is characterized by an overactive hypothalamic–pituitary–adrenal axis (HPA axis) that resembles the neuro-endocrine response to stress. These HPA axis abnormalities participate in the development of depressive symptoms, and antidepressants may serve to regulate HPA axis function.

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