Washington, Oct 25 (ANI): More than half of the people who take anti-depressants never get relief. This is because the cause of depression has been oversimplified and drugs designed to treat it aim at the wrong target, according to a new study.

The study, led by Eva Redei, psychiatry professor at Northwestern University Feinberg School of Medicine (NUFSM), appears to topple two strongly held beliefs about depression.

One is that stressful life events are a major cause of depression. The other is that an imbalance in neurotransmitters in the brain triggers depressive symptoms.

Both findings are significant because these beliefs were the basis for developing drugs currently used to treat depression.

Redei found powerful molecular evidence that quashed the long-held dogma that stress is generally a major cause of depression.

The new study has revealed that there is almost no overlap between stress-related genes and depression-related genes.

Redei’s findings are based on extensive studies with a model of severely depressed rats that mirror many behavioural and physiological abnormalities found in patients with major depression.

“This is a huge study and statistically powerful. This research opens up new routes to develop new antidepressants that may be more effective. There hasn’t been an antidepressant based on a novel concept in 20 years,” Redei said.

She took four genetically different strains of rats and exposed them to chronic stress for two weeks. Later, she identified genes in the brain regions (linked with depression in rats and human) that had increased or decreased in response to the stress in all four strains.

“This finding is clear evidence that at least in an animal model, chronic stress does not cause the same molecular changes as depression does,” Redei said.

The findings were presented at the Neuroscience 2009 conference in Chicago. (ANI)