Brody et al (2001) studied 24 untreated patients with major depressive disorder (MDD). Positron Emission Tomography (PET) brain imaging was used to provide images of the patients before and after 12 weeks of either interpersonal psychotherapy treatment or pharmacologically with Paroxetin (an SSRI). A control group of non-depressive patients were also evaluated.
Subjects with depressive symptoms at the baseline had higher metabolism than the control group in the prefrontal cortex (PFF), and lower metabolism in the temporal lobe (TL).
With treatment, the depressive subjects showed metabolic changes. Their brain scans changed to match those belonging to the normal group.
The Hamilton Depression Rating scale was used to access the experience of depression in the subjects. In both treatment groups the subjects saw decrease in depression experience. However theparoxetine-treated subjects had a greater mean decrease in Hamilton Depression Rating Scale score (61.4%) than did subjects treated with interpersonal psychotherapy (38.0%).
Both subgroups showed decreases in normalized PFF and left anterior cingulate gyrus metabolism and increases in normalized left temporal lobe metabolism; the paroxetine-treated bilaterally, while interpersonal psychotherapy-treated on the right.
This study showed that inter-personal therapy treatment effected change in the metabolic activity in the brain. The effect of the treatment is also moderately different as that from pharmacological treatment.
Further study by Martin et al. (2001), using Single-Photon-Emission Computer Tomography (SPECT), comparing 28 depressive patients treated with 6 weeks of interpersonal psychotherapy and depressive patients treated with Venlafaxin(a SSNRI).
The researchers discovered, after 6 weeks of treatment, both groups of patients showed increased cerebral blood flow in the right basal ganglia. However, when they tested the patients again on the 12th week (this means 6 weeks after treatment has completed), only the psychotherapeutically treated patients retained the increased blood flow in the right posterior cingulum.
What the studies tell us is that the treatment of depression with inter-personal psychotherapy and pharmaceuticals do alleviate depressive symptoms.
Biologically, however there is a difference in how both types of treatment work.
The significant point of the studies is, that although pharmaceutical treatment seem to work as well as psychotherapy, the effect of interpersonal psychotherapy is lasting. 6 weeks after treatment has ended, the client keeps the benefits of the psychotherapeutic treatment. Pharmaceutical treatment was shown, however, to be transient, setting the patient back to original condition when the drugs are discontinued.
Brody, A. L., Saxena, S., Stoessel, P., Gillies, L. A., Fairbanks, L. A., Alborzian, S., … & Ho, M. K. (2001). Regional brain metabolic changes in patients with major depression treated with either paroxetine or interpersonal therapy: preliminary findings. Archives of general psychiatry, 58(7), 631-640.
Martin, S. D., Martin, E., Rai, S. S., Richardson, M. A., & Royall, R. (2001). Brain blood flow changes in depressed patients treated with interpersonal psychotherapy or venlafaxine hydrochloride: preliminary findings. Archives of General Psychiatry, 58(7), 641-648.