Antidepressants start to work immediately even though patients may not notice the effects until months later, according to a report published in The American Journal of Psychiatry.
Research at Oxford University suggests that the therapeutic action rapidly begins to change negative thoughts, with subtle, positive cues adding up over time to lift the depression.
Psychiatrist Dr Catherine Harmer and her team report that patients showed positive improvements in three specific measures within three hours of taking the drug.
They were more likely to see themselves in a positive light instead of dwelling on their bad points, and were also more likely to see the positive side of others.
For example, if they encountered a bad-tempered person they no longer believed that they must have done something wrong to upset that person. However, they felt no overall improvement in mood or anxiety.
Says Dr Harmer: “We found the antidepressants target the negative thoughts before the patient is aware of any change in feeling subjectively.”