Depression affects the part of the brain which is implicated in non-reward, the lateral orbitofrontal cortex, so that sufferers of the disease feel a sense of loss and disappointment associated with not receiving rewards.
Depression is also associated with reduced connectivity between the reward brain area in the medial orbitofrontal cortex and memory systems in the brain, which could account for sufferers having a reduced focus on happy memories. These new discoveries could herald a breakthrough in treating depression, by going to the root cause of the illness and helping depressed people to stop focussing on negative thoughts.
In a particularly large study, almost 1,000 people in China had their brains scanned using high precision MRI, which analysed the connections between the medial and lateral orbitofrontal cortex, the different parts of the human brain affected by depression. Researcher Jianfeng Feng commented that depression is becoming increasingly prevalent, "More than one in ten people in their life time 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."
Researcher Edmund Rolls, looking forward to the new treatments the research could lead to, said, "The new findings on how depression is related to different functional connectivities of the orbitofrontal cortex have implications for treatments in the light of a recent non-reward attractor theory of depression."