Other patients who received medication and had that pattern didn’t improve.
On the other hand, in patients with a different pattern, medication worked and CBT didn’t.
So one day the brain test could determine which treatment to try first.
Is major depression really several illnesses?
Right now, anyone who shows at least five of the nine symptoms listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) can be diagnosed with depression.
There are at least 256 unique combinations of those symptoms, according to Dr. Conor Liston, assistant professor of neuroscience and psychiatry at Weill Cornell Medicine in New York.
One person can gain weight, another lose weight, and they’ll get the same diagnosis.
“Someone who’s suffering from weight loss, no appetite, only able to sleep four or five hours a night, very agitated, very anxious, is probably not suffering from exactly the same biological problem as someone who has gained a lot of weight because they have an increased appetite, they’re craving carbohydrates all the time; they’re sleeping 19 hours a day, can’t get out of bed, and they feel slowed and lethargic and can barely move,” Liston explained in a webinar for the Brain & Behavior Research Foundation, which gave Liston an early grant.
Liston and his team set out to “cluster patients” based on underlying biology. From there, they established “interesting or clinically useful subtypes.” The study results appeared in Nature Medicine in January, 2017.
The signs of depression aren’t obvious in a brain scan. But brain imaging can show blood flowing to different areas, and if it comes to two areas at the same time, a sign of “functional connectivity,” Liston said.
Liston’s team gathered scans of more than 500 patients with active major depression from five universities across the country. None of the patients had bipolar disorder.
The group created color-coded “maps” to display areas that tended to become active at the same time, and areas that were more likely not to become active together.
In effect, the team created a map of a depressed brain, since some of the “connectivity features” were abnormal and showed up in all these depressed patients.
The next step was matching “connectivity features” to symptoms.
Four subtypes emerged.
Two involved people suffering more serious “anhedonia”— loss of interest in their ordinary activities.
Two other groups involved people who were more anxious.
To test whether the types really described depression and not mental illness generally, the team analyzed scans of 75 patients diagnosed with schizophrenia but not depression. Almost none fit into the depression subtypes.
Using another set of scans that included people who were not depressed, the team tested whether the markers they had found could predict who was. The answer was yes, with 80 to 90 percent accuracy.
In a separate test, people diagnosed with anxiety — but not depression — showed brain scan patterns that fit the two depression subtypes characterized by anxiety.
Liston believes this result may eventually help us treat patients with anxiety as well.