Attention deficit hyperactivity disorder (ADHD) and the dietary intake of fiber and fat

Introduction: A link between consuming Western diet patterns, i.e. low fiber and high fat intake, and Attention Deficit Hyperactivity Disorder (ADHD) symptomatology has been suggested [1]. Aim of this study: To examine the relationship between the dietary intake of fiber and fat and ADHD symptomatology, with a specific interest in potential differential effects on the two core aspects of ADHD, namely Attention Deficit (AD) and Hyperactivity and Impulsivity (HI). Methods: A survey was held among healthy young Dutch students of Utrecht University, The Netherlands. The ADHD Rating Scale (ARS) was completed to assess ADHD [2]. In addition to an overall ADHD score, two subscales AD and HI were scored. Subjects were screened being positive for having AD or HI (a score of 6 or more on the subscale). The intake of dietary fiber and fat was assessed with the 20-item Fat and Fiber Behaviour Questionnaire (FFBQ) [3]. Participants could rate the frequency of dietary fat or fiber intake on a 5-point Likert scale. Besides a total index score, a separate fat-index and fiber-index was calculated from items concerning fat (13 items) and items concerning fiber (7 items). Nonparametric Spearman r correlations were computed between ARS and FFBQ outcome measures. Fat and fiber measures were also compared between subjects who screened positive for AD or HI versus those who screened negative for AD or HI. Results: The survey was completed by N= 415 students. Their mean (SD) age was 21.4 (2.2) years old, and 37.1% was men. A significant correlation was found between scores on the fatindex and AD score (r = -0.099, p = 0.047). The association with the ADHD overall rating approached significance (r = -0.095, p = 0.055), but no relationship was found with HI scores. Scores on the fiber index did not correlate significantly with any ADHD outcome measure. Finally, the overall fat-fiber index score correlated significantly only with AD (r = -0.109, p = 0.029). When analyzing these effects separately for men and women, it appeared that for men none of the correlations was significant. In contrast, in women, significant correlations were observed between fat-index scores and the ADHD overall score (r = -0.153, p = 0.016), fatindex scores and the AD score (r = -0.181, p = 0.001), and between the overall fat-fiber index score and AD (r = -0.165, p = 0.009). No significant differences in dietary fat and fiber index scores were observed between those who screened positive for having AD (3.6%, N= 15) and those who screened negative for AD. In contrast, those who screened positive for having HI (4.6%, N= 19) reported significantly higher scores on the fat-index (3.3 versus 3.0, p = 0.005), the fiber-index (3.0 versus 2.7, p = 0.029), and the overall fat-fiber index (3.2 versus 2.9, p = 0.003) when compared to individuals who screened negative for HI. Conclusion: Albeit modest, significant correlations were found between dietary intake of fat and fibers and ADHD symptomatology. Further research into the impact of diet on ADHD symptomatology and its treatment is warranted.