Writing in the British Medical Journal (BMJ) Prof Gordon Parker -senior psychiatrist said, depression had become a "catch-all" diagnosis, driven by clever marketing from pharmaceutical companies and leading to the burgeoning prescription of antidepressant drugs. Too many people are being diagnosed with depression when they are merely unhappy, he said.
He said the drugs were being marketed beyond their "true utility" in cases in which people were unhappy rather than clinically depressed.
The psychiatrist, of the University of New South Wales, Australia, said the "over-diagnosis" of depression began in the early 80s, when the diagnostic threshold for minor mood disorders was lowered.
His 15-year study of 242 teachers found that more than three-quarters met the current criteria for depression.
Qualifying symptoms included "feeling sad, blue or down in the dumps" for two weeks, or appetite change, sleep disturbance, drop in libido and tiredness.
The psychiatrist said these symptoms were so common that most people would have them at some point in their lives. Under the current diagnosis guidelines, around one in five adults is thought to suffer depression during their lifetime.