A physical source of depression has potentially been identified in a recent journal published in Brain; titled “Medial reward and lateral non-reward orbitofrontal cortex circuits change in opposite directions in depression.”
1 in 7 Australians will experience depression within their lifetimes with it being the 3rd highest burdening of all mental illnesses globally. This burden is determined by factors such as mortality (associated death), morbidity (associated sickness) and financial cost. Not only that but people diagnosed with depression show higher rates of obesity, heart disease, stroke, sleep disorders and over half of those with depression experience symptoms of anxiety too.
Research conducted by the University of Warwick and Fudan University tested 909 people and found that depression affected a region of the brain known as the orbitofrontal cortex; in particular, the lateral (outside) region. The cortex enables individuals to adapt their behaviour in response to unexpected rewards or adversities. Of the 909 people tested, 421 patients were diagnosed with major depressive disorder and 488 were control subjects with no diagnosis; this allowed for the researchers to study the differences in brain structure between patients. Using functional connectivity neuroimaging, they were able to determine the activity and strength of different connections within the brain. Functional connectivity neuroimaging works by scanning the for variations in blood flow to different areas of the brain to determine the activity in that area.
The study showed that because of increased activity within the lateral orbitofrontal cortex suffers of the disease felt a sense of loss and disappointment when not being rewarded. Thoughts of personal loss and low self-esteem were potentially associated with a link between the lateral cortex and the area of the brain involved with the sense of one’s self. It was also noted that decreased activity between the lateral, medial (inside) orbitofrontal cortex and memory sectors could explain the reason why people with depression have trouble focusing on positive memories.
Professor Jianfeng Feng commented “Our finding, with the combination of big data we collected around the world and our novel methods, 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.” She continued with “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.”
This theory proposes that in depression, the lateral orbitofrontal cortex is more easily triggered and maintains activity for longer. This results in negative states of thinking, which in turn further activates the orbitofrontal cortex; a loop of negative thinking within the mind. Scientists are hoping that treatments of depression, such as the use of ketamine, will be able to inhibit this overactive and over sensitive region of the brain; curing people of depression.