Dose-dependent effects of the selective serotonin reuptake inhibitor citalopram: A combined SPECT and phMRI study. (June 2019)

• Record Type: Journal Article
• Authors: Schrantee, Anouk; Solleveld, Michelle M; Schwantje, Hilde; Bruin, Willem B; Mutsaerts, Henk-Jan MM; Adriaanse, Sofie M; Lucassen, Paul; Booij, Jan; Reneman, Liesbeth
• Is Part Of: Journal of psychopharmacology. Volume 33:Number 6(2019)
• Page Start: 660
• Page End: 669
• Publication Date: 2019-06
• Subjects: Citalopram -- phMRI -- serotonin -- SPECT; Psychopharmacology -- Periodicals; 615.78
• DOI: 10.1177/0269881119836229
• Languages: English
• ISSNs: 0269-8811

Abstract

Background: Serotonin transporter blockers, like citalopram, dose-dependently bind to the serotonin transporter. Pharmacological magnetic resonance imaging (phMRI) can be used to non-invasively monitor effects of serotonergic medication. Although previous studies showed that phMRI can measure the effect of a single dose of serotoninergic medication, it is currently unclear whether it can also detect dose-dependent effects. Aims: To investigate the dose-dependent phMRI response to citalopram and compared this with serotonin transporter occupancy, measured with single photon emission computed tomography (SPECT). Methods: Forty-five healthy females were randomized to pre-treatment with placebo, a low (4 mg) or clinically standard (16 mg) oral citalopram dose. Prior to citalopram, and 3 h after, subjects underwent SPECT scanning. Subsequently, a phMRI scan with a citalopram challenge (7.5 mg intravenously) was conducted. Change in cerebral blood flow in response to the citalopram challenge was assessed in the thalamus and occipital cortex (control region). Results: Citalopram dose-dependently affected serotonin transporter occupancy, as measured with SPECT. In addition, citalopram dose-dependently affected the phMRI response to intravenous citalopram in the thalamus (but not occipital cortex), but phMRI was less sensitive in distinguishing between groups than SPECT. Serotonin transporter occupancy showed a trend-significant correlation to thalamic cerebral blood flow change. Conclusion: These results suggest that phMRI likely suffers from higher variation than SPECT, but that these techniques probably also assess different functional aspects of the serotonergic synapse; therefore phMRI could complement positron emission tomography/SPECT for measuring effects of serotonergic medication.