Research has shown that when we experience a positive event in our lives, our brains respond with an increase in electrical activity — a reaction known as “reward positivity.” People who suffer from depression, however, tend to show reduced brain activity in response to good things happening in their lives.
In a new study, researchers at the University of Illinois at Chicago (UIC) wanted to see if they could use reward positivity to predict which patients might do better on serotonin reuptake inhibitors (SSRIs) versus cognitive behavioral therapy (CBT). They also wanted to see whether changes in reward positivity were associated with symptom improvement over the course of treatment.
To do this, the researchers used electroencephalography, or EEG, a device which records brain activity through the scalp using a cap embedded with electrodes. A larger reward positivity signal reflects an enhanced brain response to receiving a reward.
The findings, published in the Journal of Clinical Psychiatry, show that reward positivity is directly related to symptom improvement during treatment and that those who show blunted reward positivity prior to treatment may do better with SSRIs.
“About 50 percent of people prescribed either selective serotonin reuptake inhibitors, or SSRIs, — a class of antidepressants — or cognitive behavioral therapy get better with those treatments,” said Katie Burkhouse, assistant professor of psychiatry in the UIC College of Medicine and lead author on the paper.
“We haven’t had an objective way to measure whether a patient is improving with treatment or which patients will do better on SSRIs versus cognitive behavioral therapy, until now.”
Burkhouse adds that there are serious considerations that go into prescribing either of these treatments. “SSRIs can have unwanted side effects, while CBT requires a significant amount of time and commitment, and practitioners trained in delivering CBT can be hard to find.”
For the study, the researchers recruited 63 participants with a history of anxiety or depression and 25 healthy participants with no history of mental health problems. Each wore the EEG cap while undergoing a simple computer task. They were then asked to choose one of two doors on a computer screen and told that if the right door were chosen, they would win a small amount of money. If the wrong door were chosen, they would lose money.
Next, participants with anxiety or depression were randomly chosen to take an SSRI every day for 12 weeks, or receive 12 weekly sessions of CBT delivered by a psychotherapist. After treatment, all participants underwent the monetary reward task again to determine whether there were changes in neural reactivity in response to receiving a reward.
There were two significant findings of the study, according to Burkhouse.
“The more that reward positivity increased from the baseline measurement to the final post-treatment measurement, the more participants reported a lessening of their depression or anxiety symptoms with treatment,” said Burkhouse.
“This means that reward positivity closely follows symptom improvement as treatment progresses, and as such, can be used to help determine if a particular treatment is working for a patient or not.”
The second finding was that individuals with a blunted reward positivity before starting treatment had a greater reduction in depressive symptoms if they were given SSRIs, but not talk therapy.
“These findings could help bring precision medicine closer to reality for patients with anxiety and depressive disorders,” said Dr. K. Luan Phan, professor of psychiatry in the UIC College of Medicine and a senior author on the paper.
Many depressed or anxious patients who seek treatment don’t always do well with the first therapy prescribed, because they are not able to tolerate side effects of drugs or they are not able to commit to weeks of talk therapy, said Phan, who holds the University of Illinois Center on Depression and Resilience Professorship.
“We can say with heightened certainty that being able to give them a treatment that will work for them is a big step towards helping more patients get relief from their symptoms sooner,” said Phan.