Have a functional MRI to refine a diagnosis of depression and identify the best treatment? This could become a reality if we are to believe work carried out by Stanford researchers and presented in the journal Nature Medicine.
Using brain imaging, this team identified six subtypes, or “biotypes,” of depression as well as treatments that are more or less likely to work for three of them.
Depression: different disturbances in brain functioning
About 30% of people with depression do not respond to treatment. To try to understand the origin of this phenomenon, the team brought together 801 participants who had already received a diagnosis for this psychological disorder. Their brain activity was measured – using functional MRI – while they were at rest, but also when they were engaged in different tasks. Scientists focused on regions and connections in the brain known to play a role in this disease.
“Using a machine learning approach known as cluster analysis to group patients’ brain images, they identified six distinct activity patterns in the brain regions studied“, explains the press release from their establishment.
Participants were randomly assigned to receive one of three antidepressants commonly used for depression or to undergo behavioral talk therapy.
Patients with the subtype, characterized by hyperactivity in cognitive regions of the brain, showed the best response to the antidepressant venlafaxine (commonly known as Effexor) compared to those affected by other biotypes. Patients affected by a subtype where the resting brain displays higher levels of activity in three regions associated with depression and problem solving saw their symptoms decrease with therapy.
A third subtype, characterized by lower levels of resting activity in the attention brain circuit, was less likely to see symptoms improve with talk therapy compared to other biotypes.
A discovery that can improve the treatment of depression
The researchers also noticed that biotypes were correlated with different symptoms and task performance. For example, patients with hyperactive cognitive regions had higher levels of anhedonia (inability to feel pleasure, Editor’s note) than people affected by other biotypes of depression. They also performed worse on executive function tasks.
The team specifies that one of the six biotypes discovered showed no notable difference in brain activity in the regions studied compared to the activity of people in good mental health. Professor Leanne Williams suggests that the activity could be located in an unstudied region. Indeed, the analyzes focused on regions known to be involved in depression and anxiety, “there could be other types of dysfunction in this biotype that their imaging did not capture“, recognizes the expert who plans to continue her work to test more patients and treatments.
“To our knowledge, this is the first time that we have succeeded in demonstrating that depression can be explained by different disturbances in brain functioning”explains Professor Leanne Williams, author of the study. “Essentially, this is a demonstration of a personalized medicine approach to mental health based on objective measures of brain function.”
“To truly move the field toward precision psychiatry, we need to identify the treatments most likely to be effective for patients and get them on treatment as soon as possible”adds Dr Jun Ma who participated in the research. “Having information about their brain function, particularly the validated signatures we assessed in this study, would help inform more precise treatment and prescriptions for individuals.”
