S86 Clinical neuropsychopharmacology P.4.022 Neural correlates of generalised anxiety disorder without comorbid depression: preliminary data from a functional MRI study K. Hilbert 1 ° , U. Lueken 1 , K. Beesdo-Baum 1 . 1 Technische Universitaet Dresden, Institute of Clinical Psychology and Psychotherapy, Dresden, Germany Background and Aims: Few functional neuroimaging studies on Generalised Anxiety Disorder (GAD), which is characterised by excessive and uncontrollable worries about a variety of situations accompanied by physical symptoms, are available so far. These studies reported perturbations in the amygdala, ventrolateral prefrontal cortex (VLPFC), anterior cingulate cortex and middle frontal gyrus. But as GAD samples mostly include patients with comorbid depression, it remains unclear whether the reported neural correlates result from GAD alone [1]. Preliminary data from an ongoing study is reported. We aimed to validate the neural correlates of GAD reported so far by investigating emotional processing under two different attentional states in a GAD sample without comorbid depression. Methods: N = 22 medication-free subjects (n = 10 GAD patients without depression and n = 12 healthy controls), diagnosed by a standardised clinical interview and carefully matched on age (mean = 32.09, range: 21-57), sex (17 female), and level of education (16 high-school equivalent), participated in an event-related functional magnetic resonance imaging (fMRI) session. Using an emotional processing paradigm that has been applied successfully in a more complex form before [1], subjects viewed 16 fearful and 16 happy faces, each presented for four seconds and repeated four times in randomised order. Attention was varied by instructing the subjects to rate either their internal fear or the nose-width of the faces online during the scanning on a five-point likert scale. Blood oxygen level dependent (BOLD) fMRI data were collected on a 3-T scanner and preprocessed and analysed with SPM8 (whole-brain analysis and region-of-interest, p < 0.001 uncorrected). Results: For the contrast fearful versus happy faces, GAD patients compared to healthy controls showed increased activation in the parietal cortex and decreased activation in the ventrolateral prefrontal cortex, middle frontal gyrus and middle cingulate gyrus during ratings of internal fear. When rating the nose-width of the faces, increased activation in the parietal cortex, temporal cortex, orbitofrontal cortex and ventrolateral prefrontal cortex and decreased activation in the inferior frontal operculum was found in GAD patients for the same contrast. Conclusions: Present results indicate a failure of brain areas such as the prefrontal cortex, middle frontal gyrus and middle cingulate gyrus to regulate emotional processing in GAD. These processes seem to be modulated by the attentional focus of the subjects. Results thus confirm previous findings and indicate the existence of GAD-specific neural alterations. Furthermore, a robust hyperactivation of the parietal cortex was found in GAD patients, possibly reflecting emotional memory processes during stimulus perception [2] present in GAD samples. However, no differential activation was found in the amygdala, possibly due to limited statistical power. If replicated, these results may prove relevant for the validator-based classification of the disorder and the ongoing nosological discussion. Future studies should employ comparisons of non-comorbid GAD samples with depression and other anxiety disorders to refine knowledge on GAD-specific neural correlates and determine similarities and differences between GAD and related disorders. Reference(s) [1] Beesdo, K., Lau, J.Y.F., Guyer, A.E., McClure- Tone, E.B., Monk, C.S., Nelson, E.E., Fromm, S.J., Goldwin, M.A., Wittchen, H.-U., Leibenluft, E., Ernst, M., Pine, D.S., 2009. Common and distinct amygdala-function perturbations in depressed vs anxious adolescents. Arch Gen Psychiatry 66(3), 275– 285. [2] Murty, V.P., Ritchey, M., Adcock, R.A., LaBar, K.S., 2011. Reprint of: fMRI studies of successful emotional memory encoding: a quantitative meta-analysis. Neuropsychologia, 49(4), 695–705. P.4.023 Habenular nuclei in different phases of major depressive disorder: a magnetic resonance imaging volumetric study J. De Diego-Adeli˜ no 1 ° , M. Carceller 1 , M. Serra-Blasco 1 , Y. Vives-Gilabert 2 , B. G´ omez-Anson 3 , D. Puigdemont 4 , E. ´ Alvarez 4 , V. P´ erez 4 , M.J. Portella 4 . 1 Hospital Sant Pau CIBERSAM UAB, Dept. of Psychiatry, Barcelona, Spain; 2 UAB, Port d’Informaci´ o Cient´ ıfica (PIC), Barcelona, Spain; 3 Hospital Sant Pau CIBERNED UAB, Neuroradiology, Barcelona, Spain; 4 Hospital Sant Pau CIBERSAM UAB, Psychiatry, Barcelona, Spain Purpose of the study: Habenular nucleus (HbN) is an epithalamic structure involved in stress-response, anxiety and reward-processing. It receives frontolimbic and hippocampal afferences and also projects inhibitory