Laboratory snack food intake, negative mood, and impulsivity in youth with ADHD symptoms and episodes of loss of control eating. Where is the missing link?

Abstract

To compare laboratory food intake, negative mood and trait impulsivity and their association with attention deficit hyperactivity disorder (ADHD) and loss of control (LOC) eating in youth (middle childhood to early adolescence). Ninety 10–14 year old youths with symptoms of ADHD, symptoms of LOC eating, and control participants took part in a laboratory snack food meal after having rated trait impulsivity. Negative mood was self-reported pre and post snack food meal, while representativeness of eating behavior and liking of the food was assessed post laboratory snack food meal. The ADHD group consumed more snack food than the other groups. Food intake was not influenced by negative mood or trait impulsivity. All groups exhibited a decrease in negative mood from pre to post food intake that was not accounted for by level of hunger or liking of the food. The greater food intake of the ADHD group compared to the other groups may contribute to the development of overweight and therefore be in accordance with the high co-morbidity reported between ADHD and obesity in youth. The influence of impulsivity and negative mood on food intake could not be shown, which corroborates a recent review on the association of negative mood and bingeing in adults but needs further assessment, particularly in the younger age groups.

Introduction

An increasing number of children and adolescents are being diagnosed with attention deficit hyperactivity disorder (ADHD; Boyle et al., 2011). Simultaneously, there is growing evidence of disordered eating already in childhood (Hilbert and Czaja, 2007, Tanofsky-Kraff et al., 2007). Various work groups have pointed out the high co-morbidity between ADHD and eating disorders, i.e. binge or loss of control (LOC) over eating, in children and adults (Davis et al., 2009, Mattos et al., 2004). Given that both ADHD and LOC eating increase the risk for obesity already in childhood (Fuemmeler et al., 2011, Tanofsky-Kraff et al., 2011, Tanofsky-Kraff, Yanovski, et al., 2009), mechanisms underlying the association between the conditions and related weight gain should be examined (Cortese et al., 2007, Cortese and Morcillo Penalver, 2010).

LOC eating appears to be common at a young age (Decaluwe and Braet, 2003, Glasofer et al., 2007, Lamerz et al., 2005). It is defined as experiencing LOC while consuming a subjectively or objectively large amount of food. LOC eating is associated with increased risk of eating disorder and general psychopathology, overweight, and obesity in youth (Glasofer et al., 2007, Goldschmidt et al., 2008, Goossens et al., 2007, Hilbert and Czaja, 2009).

ADHD is a condition characterized by attention deficit, hyperactivity, and impulsivity (APA, 2000). Research indicates that girls with ADHD are 3.6 times more likely to develop an eating disorder than girls without ADHD (i.e. Biederman et al., 2007). There is substantial evidence from neurochemical and genetic studies showing similarities in adults with ADHD and BED (Casey et al., 2007, Cortese et al., 2007, Davis et al., 2009, Karhunen et al., 2000, Mulder et al., 2008, Schulz et al., 2005, Woolley et al., 2007).

Both LOC and ADHD are associated with obesity and overweight. Several longitudinal studies in youths with LOC eating found it to be a predictive factor for weight gain (Tanofsky-Kraff, McDuffie, et al., 2009, Tanofsky-Kraff et al., 2011). Additionally, several studies reported a higher prevalence of ADHD in overweight youth and adults (de Zwaan et al., 2011, Fuemmeler et al., 2011) and vice versa (de Zwaan et al., 2011, Kim et al., 2011). Given the long-term consequences of overweight and obesity in youth (Reilly & Kelly, 2011), an investigation of conditions and factors contributing to their development is warranted.

Besides energy expenditure, or a lack thereof as a consequence of sedentary lifestyle (Chaput, Klingenberg, Astrup, & Sjödin, 2011), energy intake through food consumption is a relevant contributor for weight gain. Several studies in LOC eating in youth therefore have investigated food intake through laboratory test meal studies (Goldschmidt et al., 2011, Hilbert et al., 2010, Tanofsky-Kraff, McDuffie, et al., 2009). While Hilbert and colleagues reported higher energy intake in youth with LOC eating compared to children without, which was most pronounced in those with highly frequent LOC eating, the other studies did not find group differences in overall food intake (Goldschmidt et al., 2011), or only for a subgroup of overweight/obese girls with LOC eating (Tanofsky-Kraff, McDuffie, et al., 2009). All studies, however, show specific patterns of nutrients that are preferentially consumed. In youth with ADHD, so far, no such studies have been conducted.

There are multiple potential factors that might influence food intake and ultimately weight gain in these populations. One characteristic that is associated with both ADHD and LOC eating is impulsivity. Impulsivity is a core feature of ADHD (APA, 2000). In particular, behavioral disinhibition has been shown in diverse experimental studies to be a trait of ADHD (for an overview Alderson, Rapport, & Kofler, 2007). There is now initial evidence to suggest that children with LOC eating also exhibit higher impulsivity than healthy children, when assessed by self-reports and a behavioral measure using sensitivity to reward (Hartmann et al., 2010, Nederkoorn et al., 2006). Three studies in preadolescents and adolescents have shown that in particular negative urgency (Combs et al., 2011, Fischer et al., 2011, Pearson et al., 2010) is highly associated with binge eating. Negative urgency is defined as a rash impulsive action to deal with negative emotion (Whiteside & Lynam, 2001), which is in line with Heatherton and Baumeister’s escape theory, positing that eating, in particular binge eating, is used as a means to reduce negative affect in persons with bulimic symptoms (Heatherton & Baumeister, 1991). Given high impulsivity and regulation of emotion shown in youth with ADHD (Alderson et al., 2007, Barkley, 1997, Martel, 2009, Wehmeier et al., 2010), one could expect negative urgency, that is negative mood coupled with high levels of impulsivity, to be a trigger for binge eating, thus being associated with weight gain in the long-run.

To our knowledge, no study exists investigating laboratory food intake in samples of youth with ADHD and LOC eating symptoms in relation to trait impulsivity and state negative mood. The present study intends to close this research gap by studying ad libitum snack food intake in youth with ADHD symptoms, LOC eating, and control participants, while measuring trait impulsivity before as well as mood pre and post laboratory snack food meal. The main hypothesis is that both youth with ADHD symptoms and LOC eating consume more calories from snack foods compared to the control participants; and that this higher food intake is at least partly accounted for by trait impulsivity and state negative mood. Differences in food intake or its association with trait impulsivity and state negative mood between the ADHD and LOC group are not expected, as both disorders have shown to be associated with obesity, and therefore are expected to have a comparable consumption, and have been known to include dysfunctions in emotion and impulsivity regulation. A second hypothesis regarding the course of mood from pre to post food intake, is that a larger increase in negative mood is expected in youth with ADHD symptoms and LOC eating, as was summarized in a review by Haedt-Matt and Keel (2011). Again, no differences were expected between the ADHD and the LOC a group. Exploratory analyses included an examination of a co-morbid group of youth experiencing both ADHD symptoms and LOC eating.