Single photon emission computed tomography (SPECT) of anxiety disorders before and after treatment with citalopram.
BACKGROUND
Several studies have now examined the effects of selective serotonin reuptake inhibitor (SSRI) treatment on brain function in a variety of anxiety disorders including obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), and social anxiety disorder (social phobia) (SAD). Regional changes in cerebral perfusion following SSRI treatment have been shown for all three disorders. The orbitofrontal cortex (OFC) (OCD), caudate (OCD), medial pre-frontal/cingulate (OCD, SAD, PTSD), temporal (OCD, SAD, PTSD) and, thalamic regions (OCD, SAD) are some of those implicated. Some data also suggests that higher perfusion pre-treatment in the anterior cingulate (PTSD), OFC, caudate (OCD) and antero-lateral temporal region (SAD) predicts subsequent treatment response. This paper further examines the notion of overlap in the neurocircuitry of treatment and indeed treatment response across anxiety disorders with SSRI treatment.


METHODS
Single photon emission computed tomography (SPECT) using Tc-99 m HMPAO to assess brain perfusion was performed on subjects with OCD, PTSD, and SAD before and after 8 weeks (SAD) and 12 weeks (OCD and PTSD) treatment with the SSRI citalopram. Statistical parametric mapping (SPM) was used to compare scans (pre- vs post-medication, and responders vs non-responders) in the combined group of subjects.


RESULTS
Citalopram treatment resulted in significant deactivation (p = 0.001) for the entire group in the superior (t = 4.78) and anterior (t = 4.04) cingulate, right thalamus (t = 4.66) and left hippocampus (t = 3.96). Deactivation (p = 0.001) within the left precentral (t = 4.26), right mid-frontal (t = 4.03), right inferior frontal (t = 3.99), left prefrontal (3.81) and right precuneus (t= 3.85) was more marked in treatment responders. No pattern of baseline activation distinguished responders from non-responders to subsequent pharmacotherapy.


CONCLUSIONS
Although each of the anxiety disorders may be mediated by different neurocircuits, there is some overlap in the functional neuro-anatomy of their response to SSRI treatment. The current data are consistent with previous work demonstrating the importance of limbic circuits in this spectrum of disorders. These play a crucial role in cognitive-affective processing, are innervated by serotonergic neurons, and changes in their activity during serotonergic pharmacotherapy seem crucial.
MRC Unit on Anxiety Disorders, Department of Psychiatry, University of Stellenbosch, Tygerberg, 7505, Cape Town, South Africa. pcarey@sun.ac.za
Paul D
PD
Carey
James
J
Warwick
Dana J H
DJ
Niehaus
Geoffrey
G
van der Linden
Barend B
BB
van Heerden
Brian H
BH
Harvey
Soraya
S
Seedat
Dan J
DJ
Stein
D000328:Adult; D001008:Anxiety Disorders / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000187:drug effects*; D015283:Citalopram / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008032:Limbic System / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000000981:diagnostic imaging / Q000188:drug therapy; D017397:Prefrontal Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D016574:Seasonal Affective Disorder / Q000000981:diagnostic imaging / Q000188:drug therapy; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D013313:Stress Disorders, Post-Traumatic / Q000000981:diagnostic imaging / Q000188:drug therapy; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data; D016896:Treatment Outcome
D015283:Citalopram; D017367:Selective Serotonin Reuptake Inhibitors; D019690:Technetium Tc 99m Exametazime