The predictive value of HMPAO SPECT regarding treatment response in patients with major depression treated with citalopram

Abstract

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Objectives: Alterations of regional cerebral blood flow (rCBF) in prefrontal cortex and rostral anterior cingulate are conspicuous findings in patients with major depression (MD). While rCBF changes in these regions have been suggested as fuctional disease markers, so far, data in large patient samples regarding treatment response prediction to antidepressant therapy are limited. In this study, we examined the predictive value of HMPAO-SPECT for subsequent treatment response to citalopram in a large collective of depressed patients. Methods: 93 Patients with DSMR-IV-defined MD were examined with Tc-99m-HMPAO-SPECT twice, at the beginning of citalopram-treatment (t1) and after 4 weeks of treatment (t2). To determine the impact of HMPAO-SPECT with regard to subsequent treatment response, the patient sample was divided into 2 groups: responders (44 patients; decline of Hamilton Rating Scale for Depression scale (HRSD) >50% after 4 weeks of therapy) and non-responders (49 patients; decline of HRSD <50%). A two-sample t-test in SPM2 between the two subgroups was used to determine group-specific rCBF-increases and decreases (FDR-corrected, p<0.05). To exclude potential influences of age, gender and initial HRSD, these variables were treated as regressors of no interest in the statistical analysis. Results: The responder group, compared to the non-responder group, revealed significant rCBF-increases at t1 in a widespread region encompassing prefrontal and anterior/perigenual cingulate regions. No rCBF-decreases were detected in the responder group. The comparison between t1 and t2 rCBF-measurement revealed a trend (p<0.001, uncorrected) of rCBF-decrease in prefrontal cortex in the responder group, not however in the non-responder group. Conclusions: Our data in a large patient sample show that rCBF-measurements with HMPAO-SPECT provide a predictor estimate for subsequent treatment response in depressed patients undergoing antidepressant therapy with citalopram. Most notably, this effect is independent of the initial HRDS and may thus be a helpful "clinical" marker in MD patients.