PS56. A smaller percentage of unipolar depression patients with manic or hypomanic switch during acute antidepressant treatment convert to bipolar disorder

s | 19 Methods: We studied 20 healthy volunteers who were tested on two occasions receiving either ebselen (3600mg over 24 hours) or identical placebo in a double-blind, random-order, cross-over design. Two hours after the final dose of ebselen/placebo, participants underwent proton magnetic resonance spectroscopy (1H MRS) at 7 tesla (7T) with voxels placed in anterior cingulate and occipital cortex (Figure 1). Neurometabolite levels were calculated using an unsuppressed water signal as a reference and corrected for individual cerebrospinal fluid content in the voxel. Results: Ebselen produced no effect on neurometabolite levels in the occipital cortex. In the anterior cingulate cortex, ebselen lowered concentrations of inositol as well as those of glutathione, glutamine, glutamate and Glx (Table 1). Conclusions: The study suggests that at the dosage used, ebselen produces a functional inhibition of IMPase in the human brain. The ability of ebselen to lower indices of glutamate activity are consistent with its action, reported in animal experimental work, to inhibit the enzyme, glutaminase. Ebselen appears to have potential as a repurposed treatment for bipolar disorder and it would be of interest to see if similar biochemical alterations are produced by ebselen treatment in this patient group. PS55 Parkinsonism induced by valproic acid: a case report and review of literature Haruka TADA, Tomomi OGIHARA, Daimei SASAYAMA, Toshinori NAKAMURA, Nobuhiro SUGIYAMA, Yuka TAKAHASHI, and