Prof Parker carried out a study, following 242 teachers. 15 years into the study, he noted that 79 percent of the people had met the symptom and duration criteria for major, minor or sub-syndromal depression.
This caused him to concluded that it is normal to be depressed, reports the BMJ.
He also warned that over-diagnosis of clinical depression could lead to a diagnosis of it becoming less credible.
However, Prof Hickie states that if increased diagnosis and treatment has actually led to demonstrable benefits and is cost effective, then it is not yet being over diagnosed.
He insists that diagnosis and treatment has led to a reduction in suicides and increased productivity. He also adds that due to this, there has been a reduction in the stigma attached to being depressed.