SPECT proves helpful in clinical management of depression

Technetium-99m HMPAO SPECT can show brain perfusion changes in patients undergoing treatment for depression, according to Israeli researchers. The findings, which shed light on the condition's causes and proper treatment, support functional imaging use in behavioral medicine.

About 19 million people get diagnosed with depression each year in the U.S. Previous imaging studies have shown these patients have abnormal brain blood flow, but none has proven which type of perfusion impairments are transitory and which are permanent signs of the condition.

Treatment with drugs or electroconvulsive therapy has been shown to produce changes in cerebral blood flow that may be associated with clinical improvement. However, physicians do not know what treatment regimen is more effective, according to senior investigator Dr. Omer Bonne, an associate professor of psychiatry at Hadassah-Hebrew University Medical Center in Jerusalem.

"This study found that antidepressants normalized blood flow in patients with depression, while electroconvulsive therapy produced additional decreases in blood flow," he said.

Bonne and colleagues evaluated 33 patients diagnosed with depression and 25 healthy control subjects using SPECT with Tc-99m hexamethylpropyleneamine oxime (HMPAO). Patients underwent imaging before and after treatment with tricyclic antidepressants, selective serotonin reuptake inhibitors, or electroconvulsive therapy. The investigators found that cerebral blood flow increased only in patients whose depression improved. They published their findings in the August issue of the Journal of Nuclear Medicine.

Baseline regional cerebral blood flow in depressed patients was lower than in controls in the frontal, limbic, and subcortical brain regions. The improvement in blood flow suggested a positive response to pharmacotherapy. Conversely, electroconvulsive therapy led to an additional blood flow decrease in the parietotemporal and cerebellar regions.

Findings will help elucidate the mechanism of depression and its treatment. Additional studies could also determine the role of functional imaging in the management of these patients, Bonne said.

"Currently, clinical psychiatry is based almost solely on subjective observer-based judgment. Our findings suggest that objective imaging evaluations could support subjective clinical decisions," he said.

For more information from the Diagnostic Imaging archives:

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PET shows link between endorphins and depression

fMRI hints at the source of bipolar disorder