6 distinct forms of depression identified by AI in brain study

Scientists have identified six biologically distinct forms of depression, which could explain why some people don't respond to traditional treatments for the condition, such as antidepressants and talk therapy. 

In a new study, researchers analyzed brain scans of more than 800 patients who'd been diagnosed with depression and anxiety. These scans were taken as the patients were resting and while they were engaged in different tasks designed to test how their brains functioned. 

Specifically, the team compared the brains of the patients, looking for differences in the activity of specific regions and the connections between them. These brain "circuits" had previously been identified as being implicated in depression. They include the frontoparietal network, which is associated with goal-driven behavior, and the default mode network, which is tied to daydreaming. 

Using a type of artificial intelligence (AI) known as machine learning, the team was able to categorize the patients into specific groups based on their brain scans. Patients within each group differed in terms of their symptoms and their ability to complete certain tasks, the team found. They described their findings in a paper published Monday (June 17) in the journal Nature Medicine. 

For instance, patients who had high activity in regions of the brain associated with processing emotions were more likely to display feelings of anhedonia — the inability to experience pleasure — than other patients. They also performed worse than the others on tasks that assessed their executive function, or capacity to focus and manage activities. 

Related: 'Scent therapy' helps unlock memories in people with depression, trial finds

Despite being grouped under the same umbrella term of major depressive disorder (MDD), not everyone experiences depression in exactly the same way, Leanne Williams, co-senior study author and a professor of psychiatry and behavioral sciences at Stanford University, told Live Science.