Scientists have identified six biologically distinct forms of DEPRESSIONwhich may explain why some people do not 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 had been diagnosed with depression and anxiety. These scans were taken while the patients were resting and while they were engaged in various tasks designed to test how their brains were working.
Specifically, the team compared the patients’ brains, looking for differences in the activity of specific regions and the connections between them. These brain “circuits” had has been previously identified as implicated in depression. They include the frontoparietal network, which is associated with goal-directed behaviorand the default mode network, which is associated with daydreaming.
Using a type of artificial intelligence (AI) known as machine learning, the team was able to categorize patients into specific groups based on their brain scans. Patients within each group differed in terms of their symptoms and their ability to perform certain tasks, the team found. They described their findings in a paper published Monday (June 17) in the journal Nature Medicine.
For example, patients who had high activity in brain regions associated with emotion processing were more likely to display feelings of anhedonia – the inability to experience pleasure – than other patients. They also performed worse than others on tasks that assessed their executive function, or the ability to focus and manage activities.
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Despite being grouped under the same umbrella term of major depressive disorder (MDD), not everyone experiences depression in the same way, Leanne Williamsco-author of the study and a professor of psychiatry and behavioral sciences at Stanford University, told Live Science.
To be formally diagnosed with MDD, a patient must have experienced at least five of the nine possible symptoms of depression – such as depressed mood, insomnia and fatigue – for at least two weeks. However, this leaves many possible combinations of symptoms.
A better understanding of the biological reasons for a particular symptom of depression can help patients feel like they are understood and can help reduce any stigma associated with their condition, Williams said.
In a separate analysis, the team found that three of the six subtypes they had identified showed signs of being more or less likely to respond to specific treatments. For example, patients who had high activity in the cognitive regions of the brain responded better to an antidepressant called venlafaxine, which is commonly marketed under the brand name Effexor, than other subtypes.
This knowledge may be clinically useful, as up to a third of people with depression do not respond to any type of treatment. In the meantime, can take weeks or months to determine whether antidepressants, for example, will have an effect on a particular patient’s symptoms.
“To see that we can predict better outcomes in specific treatments really does that [this work] it’s really worth it,” Williams said.
This is an “extraordinary” study. Greg Siegela professor of psychiatry at the University of Pittsburgh, who was not involved in the research, told Live Science in an email.
The idea that neuroimaging-derived subtypes of depression may have important clinical differences and potentially different treatment responses could be a critical step in moving toward personalized care, he said.
The researchers now plan to test their approach on more people. They would also like to see how each subtype responds to other treatment options.
The hope is that one day, doctors may be able to match patients to the type of treatment most likely to work for them based on their subtype, Williams said.
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