Working memory dysfunction in fibromyalgia is associated with genotypes of the catechol- O-methyltransferase gene: an event-related potential study

Abstract

Recent fndings have associated diferent COMT genotypes with working memory capacity in patients with fbromyalgia. Although it is thought that the COMT gene may infuence neural correlates (P2 and P3 ERP components) underlying working memory impairment in this chronic-pain syndrome, it has not yet been explored. Therefore, the aim of the present research was to investigate the potential efect of the COMT gene in fbromyalgia patients on ERP working memory indices (P2 and P3 components). For this purpose, 102 participants (51 patients and 51 healthy control participants) took part in the experiment. Event-related potentials and behavioral responses were recorded while participants performed a spatial n-back task. Participants had to decide if the stimulus coincided or not in the same location as the one presented one (1-back condition) or two (2-back condition) trials before. Genotypes of the COMT gene were determined through a saliva sample from all participants. Present results signifcantly showed lower working memory performance (p<0.05) in patients with fbromyalgia as compared to control participants (higher rate of errors and slower reaction times). At neural level, we found that patients exhibited enhanced frontocentral and parieto-occipital P2 amplitudes compared to control participants (p<0.05). Interestingly, we also observed that only fbromyalgia patients carrying the Val/Val genotype of the COMT gene showed higher frontocentral P2 amplitudes than control participants (p<0.05). Current results (behavioral outcomes and P2 amplitudes) confrmed the presence of an alteration in working memory functioning in fbromyalgia. The enhancement of frontocentral P2 could be refecting that these patients would manifest an inefcient way of activating executive attention processes, in carriers of the Val/Val genotype of COMT. To our knowledge, the present fndings are the frst linking neural indices of working memory dysfunctions and COMT genotypes in fbromyalgia. Applying a subgroup of patient’s strategy based on this genetic marker could be useful to establish more tailored therapeutical approaches.