Most of the estimated 16 million adults who live with depression find little relief with antidepressants. This is a problem that most researchers say lies in the way the disease is diagnosed.
In modern-day psychiatry, depression is diagnosed from a list of criteria. If a patient exhibits low mood and four additional symptoms from a list of nine, they are considered to be clinically depressed. However, depression is often not this black and white. Diagnosing depression from a list of nine very different and specific symptoms has led psychiatrists to use the same medication and treatment methods for a disease that manifests very differently from person to person. One individual might be gaining weight and sleeping a lot, while another might be losing weight and feeling anxious much of the time. However, under today’s protocol, both of these individuals would receive the same types of treatment for their depression.
It is this problem that led Conor Liston, a neurobiologist at Weill Cornell Medicine, to study the neurobiology of depression. Liston and his team realized that the current generalized approach to understanding depression has hindered patients from getting treatment that is tailored to their specific needs. In a recent study, Liston and his colleagues set out to find distinguishing characteristics for different types of depression in the form of biological markers.
In Liston’s study, over one thousand fMRI scans of both depressed and non-depressed individuals were analyzed. For each subject, the researchers analyzed 258 brain areas, measuring how strong the connections were within each area of the brain. Researchers found that one brain area, called the subgenual cingulate cortex, has unusually strong connections with other regions of the brain in people who are depressed. This conclusion led Liston and his team to identify four subtypes of depression. The first two subtypes tend to exhibit more fatigue, while the other two subtypes exhibit more restlessness.
This subtyping has implications for both pharmaceutical treatment and different types of therapy. For example, Liston and his colleagues found that individuals that experienced more fatigue with their depression were more likely to benefit from a newer therapy called transcranial magnetic stimulation, or TMS. This method produces small electrical currents in certain areas of the brain, and is usually reserved for individuals who haven’t been responsive to antidepressants. However, because of the identification of different subtypes of depression, Liston and his team are hoping to be able to tell which individuals will not be responsive to antidepressants at all. He is then hoping to develop a method where the physician could scan the patient’s brain through fMRI and target the under-stimulated areas of the brain with more specificity.
This new avenue of treatment and therapy will open up more avenues to treatment than just antidepressants and therapy. Hopefully, more Americans will be able to find treatment that is tailored to their specific depression symptoms, and fewer individuals will continue to suffer in silence.
References:
Drysdale, A. T., Grosenick, L., Downar, J., Dunlop, K., Mansouri, F., Meng, Y., … Liston, C. (2016). Resting-state connectivity biomarkers define neurophysiological subtypes of depression. Nature Medicine, 23(1), 28-38. doi:10.1038/nm.4246
Liston, C., Chen, A. C., Zebley, B. D., Drysdale, A. T., Gordon, R., Leuchter, B., … Dubin, M. J. (2014). Default mode network mechanisms of transcranial magnetic stimulation in depression. Biological Psychiatry, 76(7), 517-526. doi:10.1016/j.biopsych.2014.01.023
