It’s every psychiatrist’s dilemma: Two patients sit in front of you, displaying the same symptoms and the same diagnosis. After going through the same treatment, one recovers and one doesn’t. What’s the difference?
It very well could be inside the brain itself. Scientists have learned a lot about the brain in the last few decades, but mental illnesses are still diagnosed based on symptoms—the visible tips of a tower hidden in fog. But for each person a different part of the tower may be broken.
One of the conditions showing benefits from such targeted approach is post-traumatic stress disorder, or PTSD. After being through an extremely traumatic or terrifying event, people who develop PTSD experience persistent frightening thoughts, recurring flashbacks or nightmares, and crippling anxiety that impairs their everyday life. Psychotherapy is the most effective treatment, but only works for about half of the patients. Medications are even less effective and come with physical side effects.
Emerging research suggests the variation in treatment response may have something to do with biological variability inside the brains of people with PTSD, said Amit Etkin, associate professor of psychiatry at Stanford University and an investigator at the Palo Alto VA in California. In a study presented this month at the annual meeting of the Society of Biological Psychiatry in New York, Etkin and his colleagues analyzed brain activity in 106 people with PTSD and found they show four distinct patterns, corresponding to different clinical symptoms.
In other words, patients grouped under the same diagnostic category may be quite different from each other and require tailored treatments.
In a study published in the American Journal of Psychiatry in December, Etkin and his colleagues asked 66 people with similar levels of PTSD symptoms to complete tasks that required them to manage their emotional response. For example, one task involved watching fearful faces but focusing on identifying the skin hue or gender of the faces. Meanwhile, the researchers monitored their brain activity using functional magnetic resonance imaging (fMRI).
After the brain scans, the participants were randomly assigned to receive 9 to 12 sessions of exposure therapy over a few weeks or to join a waiting list.
At the end of the study, the researchers went back to the initial brain scans. Patients who had the largest reductions in symptoms after treatment had shown greater activity in prefrontal regions and lesser activity in the amygdala in response to fearful faces. This meant these people were less emotionally reactive and better able to activates their prefrontal cortex to regulate their emotional response.
There may be a way to make psychotherapy successful for the other half as well: by stimulating and “conditioning” the brain networks, Etkin said.
Other research has shown zapping the brain to stimulate the frontal regions, using a noninvasive technique called transcranial magnetic stimulation, or TMS, can improve the connection between the frontal regions and the amygdala. The TMS device is an electromagnetic coil that is placed over the skull and can boost or lower the activity in a targeted brain region. The effect is temporary and reversible, but thanks to brain’s plasticity, repeated stimulation can lead to lasting changes in neuronal activity. In 2008, TMS was approved by the U.S. Food and Drug Administration as a treatment for some forms of depression.
In a study published in the Journal of Affective Disorders in April, Philip and his colleagues had 35 people with PTSD and depression undergo 40 daily sessions of TMS. The treatment reduced the symptoms of both conditions, enough that half of the patients were no longer experiencing symptoms severe enough that required further treatment.
Several other groups have seen PTSD patients benefits from TMS, raising the idea that the brain stimulation techniques could be coupled with existing treatments, such as psychotherapy.