"We found that older men who were using antidepressants but remained depressed had a substantially higher mortality risk. However, men using antidepressants who were free of depressive symptoms had a similar mortality risk over 10 years as the rest of the population.
"The most plausible explanation for these results is that the increased mortality risk associated with antidepressant use is not due to the medication itself, but to the persistence of depressive symptoms despite treatment. In other words, it is the depression that is contributing to shorten people's lives."
Professor Almeida said the results of the study showed more needed to be done to improve the efficacy of current antidepressant treatments.
"More than half of older men with depression who use antidepressants or psychotherapy fail to respond fully to the treatment," he said.
"We need to do something urgently to improve the efficacy of our treatments for depression. We are currently running two new studies at our Centre that try to do just that."
Depression is a common and disabling condition that affects one in 10 people over the age of 60 years living in the community.
Professor Almeida and his team assessed the health and lifestyle of 5,276 men aged over 68 years who had been living in Perth for more than a decade. Their health status was assessed periodically over the decade.