The experts are of the belief that the elimination of bacteria and viruses has made our immune system weaker which has subsequently affected the functioning of our brains, preventing the production of feel good chemicals such as serotonin.
The researchers pointed out that rates of depression among the worlds poorer nations are far lower than those in the western world, with around 1 in 10 Brits suffering from depression compared to just one in a hundred in Nigeria.
A scientist on the study, Dr Andrew Miller, said: ‘We believe the immune system is causing depression.’
‘As people develop and grow up, their immune system develops. If they are exposed to more bacteria and parasites, they are able to better control the inflammation.
‘Nowadays people’s environment is much cleaner and hygienic so our immune system never really learns how to deal with infectious agents. We are overactive because our immune system has not been trained.’ He said.
The scientists studied how the inflammation or over-reaction affected the brain by recruiting 27 participants to take drugs designed to treat hepatitis C (which causes similar reactions).
The researchers concluded that certain reactions could prevent the brain from producing feel good hormones such as serotonin and they have now moved on to testing whether anti-inflammatory drugs could be used to treat depression.