A psycho-genetic study of associations between the symptoms of binge eating disorder and those of attention deficit (hyperactivity) disorder Caroline Davis a,b,c, * , Karen Patte a,b , Robert D. Levitan b , Jacqueline Carter c , Allan S. Kaplan b,c , Clement Zai b , Caroline Reid a,b , Claire Curtis a,b , James L. Kennedy b a Faculty of Health Sciences, York University, Centre for Addiction and Mental Health, 343 Bethune College, 4700 Keele Street, Toronto, ON, Canada M3J 1P3 b Centre for Addiction and Mental Health, Toronto, Canada c Psychiatry, University Health Network, University of Toronto, Canada article info Article history: Received 20 May 2008 Received in revised form 17 October 2008 Accepted 21 October 2008 Keywords: ADHD Binge eating Obesity DRD3 Dopamine abstract Objective: Some recent studies have reported intriguingly strong correlations between ADHD and obes- ity. This study examined whether ADHD symptoms were more pronounced in adults with symptoms of binge eating disorder (BE) than in their non-binging obese counterparts, and whether the links were stronger with inattentive vs impulsive/hyperactive symptoms. We also assessed the role of the dopamine D3 receptor in ADHD symptoms since the DRD3 gene has been associated with impulsivity and drug addiction – both relevant features of ADHD. Methods: A case (BE: n = 60) double-control (normal weight: n = 61 and obese: n = 60) design was employed. Assessments of both childhood and adults ADHD symptoms were made, as well as genotyping of seven markers of DRD3 including the functional Ser9Gly polymorphism. Results: Three DRD3 genotypes, including Ser/Ser, had significantly elevated scores on the hyperactive/ impulsive symptom scale. In turn, the four ADHD symptom scales were all significantly elevated in the BE and obese groups, who did not differ from each other, compared to those with normal weight. Conclusions: Results indicated a role for the D3 receptor in the manifestation of the hyperactive/impul- sive symptoms of ADHD, and that symptoms of ADHD are significantly, but not differentially, elevated in obese adults with and without binge eating. Our findings suggest that ADHD screening in adults seek- ing treatment for obesity, including those with BE, may be warranted as methods used to treat ADHD may help some to better manage overeating and other factors contributing to weight gain. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Attention deficit/hyperactivity disorder (ADHD) was initially seen as a childhood disorder that typically remitted with puberty (Mayes and Rafalovich, 2007). Views changed with the evidence that 70–80% of children with ADHD retain some of their symptoms in adolescence, and that in a substantial number of cases, one or more disabling features of the disorder persist into adulthood (Bie- derman et al., 1996; Mannuzza et al., 1998). However, the quality of the core characteristics tends to change with maturity. For example, the overt and extreme restlessness seen in children is usually chan- neled into more socially appropriate behaviours (Weiss et al., 1999). There is a wealth of research demonstrating an association be- tween ADHD and addiction disorders – a co-morbidity that is both robust and bi-directional (e.g. Fuemmeler et al., 2007; Ohlmeier et al., 2007; Tang et al., 2007). Moreover, the conclusions from a re- cent familial-risk analysis are that ADHD and drug dependence share a common vulnerability profile rather than present with independent modes of transmission (Biederman et al., 2008). Since both disorders have strong links to the dopamine (DA) system, Bie- derman and his colleagues propose the conjoint involvement of DA genes that regulate arousal, attention, and the common reward pathway. 1.1. ADHD and obesity In recent years, we have also become aware of strong links be- tween ADHD and obesity (e.g. Agranat-Meged et al., 2005; Altfas, 2002; Fleming et al., 2005) – an association of particular interest because of their individual connectedness to addictive behaviours. First, there is some evidence that highly palatable food can be an addictive substance, and that compulsive overeating can be mod- elled as an addictive behaviour (Avena et al., 2008; Davis et al., 2008; Trinko et al., 2007; Volkow and O’Brien, 2007). Second, is 0022-3956/$34.00 Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpsychires.2008.10.010 * Corresponding author. Address: Faculty of Health Sciences, York University, Centre for Addiction and Mental Health, 343 Bethune College, 4700 Keele Street, Toronto, ON, Canada M3J 1P3. Tel.: +1 416 736 2100x77327; fax: +1 416 736 5774. E-mail address: cdavis@yorku.ca (C. Davis). Journal of Psychiatric Research 43 (2009) 687–696 Contents lists available at ScienceDirect Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/jpsychires