3 . Setting : Goldsmiths College, University of London.

1. Examining electrophysiological response to alcohol-related stimuli in non-dependent heavy drinkers Matthew J. Mayhew1, José Van Velzen1, Jane H. Powell1, & David M. Ball2 1Goldsmiths College, University of London 2Institute of Psychiatry, King’s College London Correspondence: Contact Matthew Mayhew (m.mayhew@gold.ac.uk). 1. Aims: To examine P3 amplitudes in response to alcohol-related (AR) and household-related (HR) words in non-dependent heavy drinkers (HDs) and light drinkers (LDs). Figure 1: ERPs elicited by AR and HR words at posterior electrodes (P1, P2, P3, P4, P03, and P04) in heavy drinkers (n = 12) (left panel) and in light drinkers (n = 10) (right panel) 2. Design: 2 x 2 mixed-measures, with the independent-measures factor of drinking group (2 levels: HDs and LDs) and the repeated-measures factor of word-type (2 levels: AR and HR). Participants had abstained from alcohol for at least 12 hours prior to testing. Participants’ event-related potentials were recorded whilst they were shown a block of 134 AR and a block of 134 HR words during one testing session; order of the two conditions was counter-balanced. In each block, a set of 17 words was randomly repeated eight times. At the end of the session, participants rated the word stimuli for affective salience. 3. Setting: Goldsmiths College, University of London. 4. Participants:Twenty-three students at Goldsmiths College. 12 were HDs (females drinking more than 16 units per week and males drinking more than 26 units per week) and eleven were LDs (females drinking between 1-2 units per week and males drinking between 1-6 units per week). Participants were excluded if they had a current or previous diagnosis of addictive disorder. Figure 2: Mean P3 amplitude in heavy and light drinkers [significant WORD-TYPE x GROUP interaction: F (1, 20) = 4.89; p = 0.04, in mixed-measures ANOVA] Figure 3: Mean affective salience ratings in heavy and light drinkers [significant WORD-TYPE x DRINKING GROUP interaction: F (1, 19) = 8.06; p = 0.01, in mixed-measures ANOVA] 6. Findings and Conclusions: • Within HDs, greater P3 amplitudes were observed in response to AR compared to HR words; within LDs, there was no difference in P3 amplitudes to AR and HR words (see Figures 1 & 2); • Within HDs, greater affective salience was attributed to AR compared to HR words; in LDs, there was no difference in affective salience ratings for AR and HR words (see Figure 3); • In non-dependent drinkers, affective and brain responses to alcohol-related cues vary as a function of drinking level. 5. Measurements:Mean P3 amplitudes, consisting of the mean voltages occurring throughout the P3 relative to a prestimulus baseline, were calculated separately for AR and HR words. Participants rated the words for affective salience on an 11-point scale ranging from 0 (“neither positively nor negatively arousing”) to 10 (“extremely positively or negatively arousing”).