A randomized controlled pilot study into the effects of a restricted elimination diet on family structure in families with ADHD and ODD Lidy M Pelsser 1 , Daphne J van Steijn 2 , Klaas Frankena 3 , Jan Toorman 4 , Jan K Buitelaar 2,5 & Nanda N Rommelse 2,5 1 ADHD Research Centre, Eindhoven, The Netherlands. E-mail: lmjpelsser@adhdresearchcentre.nl 2 Karakter Child and Adolescent Psychiatry University Centre, Nijmegen, The Netherlands 3 Wageningen University, Quantitative Veterinary Epidemiology Group, Wageningen, The Netherlands 4 Catharina Hospital, Eindhoven, The Netherlands 5 Departments of Psychiatry and Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, The Netherlands Background: Behavioural improvements of children with attention-deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) following a restricted elimination diet (RED), may be due to concurrent changes in family environment. Methods: Twenty-four children with ADHD, were randomized to either a 5-week RED intervention, or a control intervention consisting of healthy food advices in a pilot study. Results: No differences in family environment were found, neither at baseline nor when comparing the start and end measurements of both groups. Conclusions: In this pilot study, the effects of an RED on ADHD and ODD are not mediated by improvement of family environment in families motivated to follow an RED. Replication of this preliminary study in larger groups of children is advised. Key Practitioner Message: ● Family environment in families of children with ADHD successfully adhering to a 5-week restricted elimina- tion diet (RED), appears to be above average ● In families adhering to a 5-week RED, family environment does not change due to the RED ● The beneficial effects of an RED on ADHD and ODD are not mediated by concurrent changes in family envi- ronment ● There is an inverse relationship between the number of ADHD and ODD symptoms and family relationships Keywords: ADHD; ODD; restricted elimination diet; family environment Introduction Attention-deficit hyperactivity disorder (ADHD), charac- terized by problems in attention, impulse control and activity regulation (American Psychiatric Association, 2000), is one of the most common psychiatric disorders, with a strong genetic disposition (Faraone & Mick, 2010). Both biological as well as psychosocial environ- mental factors are related to ADHD, including prenatal maternal smoking, prematurity, low birth weight, foetal distress, foster placing and disturbed parent–child rela- tionships (Banerjee, Middleton & Faraone, 2007; Bieder- man & Faraone, 2005; Deault, 2010). An important, albeit controversial, environmental factor that may trig- ger ADHD is food (Arnold, 1999). Research investigating the effects of additives like colourings and preservatives on ADHD, has shown that although additives may have some effects on the behaviour of all children [effect size (ES) 0.3], additives do not cause ADHD (McCann et al., 2007). Conversely, recent research investigating the effects of a restricted elimination diet (RED), that is, eliminating many kinds of foods from the child's diet, has shown statistically significant and clinically relevant results, with ES on the ADHD DSM-IV Rating Scale vary- ing from 1.7 according to the open teacher measure- ments to 2.0 according to the blinded paediatrician measurements (Pelsser et al., 2011). These results confirm the outcomes of seven previous randomized controlled trials, investigating the effects of an RED on ADHD, with an overall ES of 1.6 (Pelsser et al., 2011). One could argue that the children's behavioural changes might be due to concomitant improvement of parental behavioural strategies, caused by the strict parental supervision necessary to comply with the RED. Research has shown that ADHD is associated with dis- ruptive parent–child relationships and poor parenting structure (Foley, 2011; Harpin, 2005; Pressman et al., 2006; Verhoeven, Junger, Aken van, Devokić & Aken van, 2010), even more when children are suffering from comorbid oppositional defiant disorder (ODD; Deault, 2010). Conversely, consistent parenting and positive par- ent–child interactions are associated with improvements of child behaviour (Kaminski, Valle, Filene & Boyle, 2008). This suggests the possibility that behavioural © 2012 The Authors. Child and Adolescent Mental Health. © 2012 Association for Child and Adolescent Mental Health. Published by Blackwell Publishing, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main St, Malden, MA 02148, USA Child and Adolescent Mental Health 18, No. 1, 2013, pp. 39–45 doi:10.1111/j.1475-3588.2012.00652.x