One of the most staggering statistics in healthcare is related to depression: 350 million people suffer from it, and 800,000 of them end their own lives every year as a result of it being left untreated.
The more the condition is understood, the better medical professionals will be at treating it – and although researchers have made major strides forward in the last few decades, much still remains a mystery. However, evidence is mounting that it’s a neurological disorder rather than an exclusively psychological one, and a new study led by a team at the University of Edinburgh bolsters this theory.
According to their study in the journal Scientific Reports, depression is linked to changes in the structure of the brain itself. Specifically, the white matter – which contains intricate neural communication networks – appears to be significantly altered in patients suffering from the condition.
This groundbreaking study, which looked at the brains of 3,461 patients, is the most expansive of its kind to date. They were drawn from a public database, UK Biobank, which contains detailed health data on 500,000 people.
Traditional magnetic resonance imaging (MRI) techniques can be used to view the entirety of the brain, but for this study, the white matter had to be isolated. In order to achieve this, the team used an advanced technique known as "diffusion tensor imaging”, which looks at how water rather than blood diffuses around the brain.
This revealed detailed maps of the patients’ white matter, which allowed the team to look for very small structural differences between samples.
Subjects who had reported suffering from depression, or afflicted by symptoms linked to depression, had noticeably different structures in their white matter compared to mentally healthy people. The key measure here was something known as “white matter integrity”, and the prevalence of depression seemed to negatively correlate with this.
The exact causal mechanism linking depression with these structural differences is uncertain at this point. Does having depression cause these structural changes or do these structures indicate that a person is more likely to suffer from depression than others?
Either way, the study adds credence to the idea that depression has a neurobiological basis, or at least a biological one. Over the last few years, genetic links to depression have been found too.
This line of reasoning doesn’t mean that psychology plays no role, but it suggests that there may be detectable biological markers of the condition. These could lead to earlier detections, which leads to more effective treatment.
Depression is by far the world’s most common disability, but it’s still arguably one of the least well understood. Studies like these help shine a light into a darkness that cuts millions of lives short.