rCBF changes in OCD patients receiving antidepressants

It is generally accepted that obsessive compulsive disorder (OCD) patients have consistently increased rCBF or rCGM in prefrontal regions. Symptoms of OCD improve with antidepressants that are serotonin reuptake inhibitors (SSRIʹs) but less so with antidepressants that are norepinephrine reuptake inhibitors. Recently, we have demonstrated that both sertraline, an SSRI and desipramine, a predominantly norepinephrine reuptake inhibitor reduced frontal rCBF in OCD patients who also suffered major depression. In patients receiving sertraline, this effect was more focused and was more pronounced in the right prefrontal region. Clinically, symptoms of depression and OCD improved to various degrees with both medications. The aim of the present study was to examine differences in rCBF between patients whose obsessive-compulsive symptoms improved and patients whose symptoms failed to improve, irrespective of the medication that they received. It was hypothesized that greater blood flow reductions in prefrontal regions would occur in improved than in unimproved patients. Sixteen drug free and physically healthy patients were diagnosed with OCD and major depression by means of the SCID. Six were male, the average age was 39.2 years (range 22 to 65). Fourteen were Caucasian, one was African-American and one was Oriental. Their average education was 16.5 years (range 13 to 20). Using a double-blind design, patients were placed randomly on sertraline or desipramine for 12 weeks. The dose was gradually increased to a maximum of 200 mg sertraline or 300 mg desipramine per day. Compliance was assessed by obtaining plasma blood levels. Weekly assessments were made with the Yale-Brown Obsessive Compulsive Scale (YBOCS), the NIMH Global OCD Rating Scale and the Hamilton Depression Scale. rCBF was measured during the drug free period and after 12 weeks of medication by Single Photon Emission Tomography (SPECT), with Tc99m HMPAO as blood flow tracer. Images were obtained using a triple head camera in a quiet room while patients kept their eyes closed. Images were analyzed using statistical parametric mapping (SPM), a method that allows statistically significant rCBF differences between two study conditions to be displayed graphically. In eleven patients, symptom reduction of 30 percent or more occurred on the YBOCS (responders). Five patients did not respond to treatment (nonresponders).: Responders showed a marked decrease in rCBF in both frontal lobes, especially the left frontal lobe while nonresponders exhibited no clear blood flow differences between pre- and post-treatment conditions.