In an article in the journal Frontiers in Psychiatry Christine DeLorenzo, PhD and colleagues reported the results of a pilot study that may help doctors predict in advance which patients are likely to benefit from the use of selective serotonin reuptake inhibitors (SSRIs) for the treatment of Major Depressive Disorder.
The identification of a readily available biomarker that predicts response to SSRIs would be of great benefit to clinicians and patients. Each year 6.7% of adults in the United States experience an episode of major depression. While SSRIs have been shown to be an effective treatment for some patients, clinicians have no reliable way to know in advance which patients are more likely to respond and which are not.
Following leads from previous studies, Dr. DeLorenzo and her colleagues used diffusion-weighted MRI to visualize the tracts leading from the raphe nucleus, the region in the brain where most serotoninergic neurons originate, and the midbrain to the amygdala and hippocampus, both of which have been implicated in depression. They were able to demonstrate a significant association between response to SSRIs and estimates related to white matter integrity (called fractional anisotropy) in tracts from the raphe/midbrain to the right amygdala. They found that average fractional anisotropy in tracts to the right amygdala was significantly lower in patients whose depression did not remit after 8 weeks of treatment than in those whose depression remitted. In addition, there was a significant correlation between pre-treatment fractional anisotropy in these tracts and the percent improvement in depression symptoms (as assessed by the Hamilton Depression Rating Scale). They observed a weaker association with regard to the left amygdala and no significant differences when the hippocampus was the target. Their findings suggest that response to SSRIs may be related to the integrity of tracts originating in the raphe/midbrain and terminating the amygdala.
The article titled “Prediction of selective serotonin reuptake inhibitor response using diffusion-weighted MRI” was published March 6, 2013. Dr. DeLorenzo, who is an Assistant Professor of Psychiatry
and Assistant Professor of Biomedical Engineering, is the director of the Brain Imaging Division of the Department of Psychiatry and Behavioral Science at Stony Brook University.