A (B)link Between Anorexia Nervosa and Dopamine?
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Anorexia nervosa (AN) is a chronic and relapsing disorder associated with low body weight and food restriction. Alterations in dopaminergic function may be important in the pathophysiology of the disorder. Researchers have studied these alterations in spontaneous eye blink rate and acoustic startle, but results have been mixed. The primary aim of this study was to attempt to understand these inconsistencies by considering the effects of medication and comorbid mood and anxiety disorders on these eye blink measures and how they relate to prediction error—an indirect measure of dopaminergic function. Individuals with AN (N = 21) and healthy controls (HC; N = 50) completed interviews and questionnaires to assess demographics, psychiatric history, and typical symptoms of AN. They also completed a spontaneous eye blink task, an acoustic startle task, and a taste reward task in an fMRI machine to measure prediction error. Data were analyzed in SPSS using a 2 (Group: AN vs. HC) x 1 multivariate analysis of variance (MANOVA) with spontaneous eye blink rate, average baseline eye blink amplitude, and startle response as dependent variables and medication and mood and anxiety disorders as covariates. Partial correlations and Spearman’s correlations evaluated the relation between prediction error and eye blink measures. Data indicate no differences in eye blink response between individuals with AN and HC. Greater average baseline eye blink amplitude was associated with greater prediction error response of individuals with AN in the right and left caudate head, the right and left nucleus accumbens, the right inferior orbital frontal cortex, and the left ventral anterior insula. No other relations between prediction error and eye blink response were found. These results reveal that dopaminergic alterations in AN are not reflected in eye blink response. There may be other factors that play a role in eye blink response of individuals with AN. Identifying potential neurotransmitter interactions within spontaneous eye blink rate and acoustic startle response may help explain why inconsistencies in the literature remain.