The findings could lead to new treatments for depression by targeting the root cause of the illness and helping depressed people to stop focusing on negative thoughts, the team said.
“More than one in ten people in their lifetime suffer from depression, a disease which is so common in modern society and we can even find the remains of Prozac – a depression drug – in the tap water in London,” said researcher Jianfeng Feng. “Our finding enables us to locate the roots of depression, which should open up new avenues for better therapeutic treatments in the near future for this horrible disease.”
After using high-precision MRI to scan the brains of nearly 1,000 volunteers, half with depression and half without, the team found that the medial and lateral orbitofrontal cortexes, areas of the brain associated with emotion and reward, are wired up differently in those suffering from depression.
The lateral orbitofrontal cortex is activated during feelings of disappointment such as when expected rewards are not received. The researchers found that in depression sufferers it is more closely connected to areas of the brain involved in one’s sense of self, and so could therefore explain their negative self-perception and lower self-esteem.
They also found reduced connectivity between the reward brain area in the medial orbitofrontal cortex and memory systems elsewhere, meaning depression sufferers are less likely to recall happy memories.