The impact of antidepressants and genetic polymorphisms on emotion.

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Selective serotonin reuptake inhibitors (SSRIs) are a type of medication and are a first line treatment for major depression and anxiety. While recent studies have shown that neuroimaging and genetics may be used to predict response to SSRI treatment, (see Kemp, Gordon, Rush, & Willams, 2008 for review) basic experimental research is needed to determine exactly how the effects of SSRIs improve symptoms of depression and anxiety. Acute administration of SSRIs may increase processing of positive emotional information, providing a foundation for subsequent changes in thoughts and behaviour (see Harmer, 2008). In order to examine this further, a number of critical issues remain to be addressed. One such issue is the serotonin transporter (5­HTT) gene. The different forms of this gene (5­HTT polymorphisms; l/l, l/s, or s/s alleles) have been reported to moderate the impact of SSRIs on emotion perception (Hinkelmann et al., 2010). However, researchers are yet to examine the interacting roles of SSRIs and the 5­HTT polymorphisms on emotional processing in real­time. A second issue is that researchers are yet to account for the different types of emotional processing and emotion regulation strategies under different conditions. Aims: The aims of this study are to examine the impact of acute administration of an SSRI (escitalopram oxalate) and 5­HTT polymorphisms on covert and overt emotion processing and strategies to regulate this processing. Participants: 50 students will be recruited from first year Psychology students, genotyped and scanned under placebo and escitalopram conditions using a randomised controlled design. Given 5­HTT polymorphisms frequencies of 30% (l/l), 50% (l/s), and 20% (s/s) it is expected that a minimum of 15 participants homozygous for the L ­allele and 35 participants with at least one copy of the S ­allele will be recruited. Treatment: Administration of escitalopram oxalate (20mg) or placebo (saccharin, an artificial sweetener). Participants will complete experimental tasks once peak absorption has been reached. One week later (for compete elimination of drug), participants will be administered the alternate treatment and complete the experimental tasks once again. Tasks: Data will be collected using functional magnetic resonance imaging (fMRI) during rest, covert and overt emotion processing of different images from the International Affective Picture System. Participants will be asked to either passively view or reappraise emotions evoked by the presented stimuli. Questionnaires: Depression, Anxiety and Stress Scales; Patient Health Questionnaire; GAD­7 anxiety questionnaire; Early life stress; Ratings of emotional images Experimental Design: 2 Group (5­HTT s­allele, l­allele) X 2 (escitalopram oxalate, placebo) within­-subject design.

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