Short-Long Functional Polymorphism of Serotonin Transporter Gene Modulates the Acute Citalopram Challenge PhMRI Response

Darragh Downey¹, Gabriella Juhasz², Shane McKie², Karen Elizabeth Davies¹, Emma Jane Thomas², Diana Chase², Rebecca Elliott², John Francis William Deakin², Ian Muir Anderson², Stephen Ross Williams¹

We investigated whether citalopram-challenge phMRI, as a probe of serotonin transporter function, would detect functional variants of the serotonin transporter gene and how this may influence normal serotonergic function. 42 normal volunteers underwent phMRI with intravenous 7.5mg citalopram. Homozygous Short/Short allele carriers had reduced BOLD responses bilaterally in the caudate, mid-cingulate gyrus and parietal cortex and increases in the superior frontal gyrus compared with the Long/Long carriers. The results offer the first direct evidence that the short and long variants of the 5HTT promoter region indeed influence synaptic 5HT function in the living human brain.