The benefits of regular exercise for general health are well known, and in recent years the association between regular exercise and improved cognitive function has been reviewed in the literature.1-3
Exercise may be beneficial for individuals with ADHD,4,5 although the majority of supporting studies are limited in size.
A meta-analysis of eight randomised controlled trials assessing the effects of physical exercise in children with ADHD (n=249) indicated that short-term aerobic exercise was effective in alleviating impairments in attention, hyperactivity, impulsivity, anxiety, executive function and social disorders.6 However, the authors concluded that the results should be viewed with caution given the small number of studies and the heterogeneity of the outcomes.6
Other studies that investigated the effects of exercise on symptoms of ADHD include:
- A study of a 10-week moderate-to-high–intensity exercise programme in children with ADHD (n=21, aged 7–12 years). Significant improvements versus controls were seen on three subscales of the Child Behavioural Checklist (thought problems, attention problems and social problems).7
- An investigation of the effects of a 30-minute moderate-intensity aerobic exercise session in children with ADHD (n=40). A control group of children watched a running/exercise-related video. Following the exercise session, children with ADHD demonstrated improvements in Stroop Test and Wisconsin Card Sorting Test performance (non-perseverative errors and categories completed). No improvements were seen in the control group.8
- Pontifex et al investigated the effect of a 20-minute moderate-intensity aerobic exercise session in pre-adolescent children with ADHD (n=20; aged 8–10 years). Task performance and event-related brain potentials were measured whilst participants performed an attentional-control task. Following the exercise session, greater response accuracy and stimulus-related processing were observed in both children with ADHD and matched controls. Children with ADHD also showed selective enhancements in regulatory processes following exercise, compared with after a reading exercise.4
In a pilot study of adults with ADHD (n=30; mean age 27.3 years), those who engaged in frequent aerobic physical activity had reduced behavioural impulsivity and less worrisome thoughts compared with those who engaged in non-frequent physical activity.5
Many small studies have assessed the effects of dietary interventions for the management of ADHD symptoms – such as restriction or elimination diets, or dietary supplementation with iron, vitamins, minerals and omega-3/6 fatty acids.9-13
Fatty acid supplementation
In a large observational study in children with ADHD aged 5–12 years (n=810), omega-3 and omega-6 fatty acids in combination with supplementary magnesium and zinc showed a beneficial effect on attentional, behavioural and emotional problems.14
A meta-analysis of eleven probably-blinded studies by Sonuga-Barke et al11 reported small but significant (p=0.04) reductions in ADHD symptoms in association with free fatty acid supplementation (Figure). Five of the eleven studies assessed the effects of omega-3 supplements, two studies assessed omega-6 supplements, and four studies assessed both omega-3 and omega-6 supplementation. Free fatty acid supplementation effects remained significant when only the nine trials with no/low medication use were considered (standardised mean difference 0.17; 95% confidence interval [CI] 0.01–0.34).11
Supplementation with free fatty acids. Reproduced with kind permission.11
Artificial food colourings
In the same meta-analysis, dietary exclusion of artificial food colours had a statistically significant effect on symptoms of ADHD (p=0.004), although the participants in these studies were often predisposed to food sensitivities (Figure).11
Artificial food colour exclusions. Reproduced with kind permission.11
Further cautious support for the potential benefits of eliminating artificial food colourings from the diet of patients with ADHD comes from a meta-analysis published in 2012.33 This study estimated that a restrictive diet may improve ADHD symptoms in around 30% of children with ADHD (data from six placebo-controlled studies; n=195).
Across 20 studies (n=794) analysing potential effects of food colouring on symptoms of ADHD, parental reporting indicated an effect size of 0.18 (95% CI 0.08–0.29; p=0.0007), although when corrected for potential publication bias, effect size was reduced to 0.12 (95% CI 0.01–0.23; p<0.05).33
- Teacher/observer reporting (10 studies; n=323) on the effects of food colouring was not found to be significant (effect size 0.07; 95% CI -0.03–0.18; p=0.14)33
- However, analysis of six high-quality studies (n=76) specifically examining colour addititives revealed a significant teacher/observer-reported effect on ADHD symptoms (effect size 0.22; 95% CI 0.10–0.41; p=0.030).33
The study authors concluded that although the effects of artificial food colourings on symptoms of ADHD were notable and warranted further investigation, they were susceptible to publication bias or were derived from small, non-generalisable samples.33
In a randomised controlled trial investigating the efficacy of micronutrient treatment (which contained all vitamins with the exception of Vitamin K, and 16 minerals) in adults (aged ≥16 years) with ADHD over 8 weeks, 42 patients received the supplement and 38 patients received placebo.10
- Significant inter-group differences on the self- and observer-rated Conners’ Adult ADHD Rating Scale (CAARS) for total Diagnostic and Statistical Manual of Mental Disorders (DSM) ADHD symptoms favoured treatment with micronutrient supplementation (p=0.009 and p=0.026, respectively); this was not observed for the clinician-rated CAARS DSM ADHD ratings10
- Clinician-rated Clinical Global Impression-Improvement Scale (CGI-I)–ADHD and CGI-I–Overall Impression showed improvements in patients receiving the supplement versus those receiving placebo (p=0.020 and p=0.012, respectively)10
- There were no inter-group differences in Montgomery–Åsberg Depression Rating Scale score.10
There is a lack of specific clinical guidance governing the use of physical exercise or dietary interventions in ADHD – current recommendations, including National Institute of Health and Care Excellence (NICE) guidelines, advocate the importance of regular exercise, a balanced diet and good nutrition for children, adolescents and adults with the disorder.34
- Ploughman M. Exercise is brain food: the effects of physical activity on cognitive function. Dev Neurorehabil 2008; 11: 236-240.
- Gapin JI, Labban JD, Etnier JL. The effects of physical activity on attention deficit hyperactivity disorder symptoms: the evidence. Prev Med 2011; 52(Suppl 1): S70-S74.
- Ratey JJ, Loehr JE. The positive impact of physical activity on cognition during adulthood: a review of underlying mechanisms, evidence and recommendations. Rev Neurosci 2011; 22: 171-185.
- Pontifex MB, Saliba BJ, Raine LB, et al. Exercise improves behavioral, neurocognitive, and scholastic performance in children with attention-deficit/hyperactivity disorder. J Pediatr 2013; 162: 543-551.
- Abramovitch A, Goldzweig G, Schweiger A. Correlates of physical activity with intrusive thoughts, worry and impulsivity in adults with attention deficit/hyperactivity disorder: a cross-sectional pilot study. Isr J Psychiatry Relat Sci 2013; 50: 47-54.
- Cerrillo-Urbina AJ, Garcia-Hermoso A, Sanchez-Lopez M, et al. The effects of physical exercise in children with attention deficit hyperactivity disorder: a systematic review and meta-analysis of randomized control trials. Child Care Health Dev 2015; 41: 779-788.
- Verret C, Guay MC, Berthiaume C, et al. A physical activity program improves behavior and cognitive functions in children with ADHD: an exploratory study. J Atten Disord 2012; 16: 71-80.
- Chang YK, Liu S, Yu HH, et al. Effect of acute exercise on executive function in children with attention deficit hyperactivity disorder. Arch Clin Neuropsychol 2012; 27: 225-237.
- Konofal E, Lecendreux M, Deron J, et al. Effects of iron supplementation on attention deficit hyperactivity disorder in children. Pediatr Neurol 2008; 38: 20-26.
- Rucklidge JJ, Frampton CM, Gorman B, et al. Vitamin-mineral treatment of attention-deficit hyperactivity disorder in adults: double-blind randomised placebo-controlled trial. Br J Psychiatry 2014; 204: 306-315.
- Sonuga-Barke EJ, Brandeis D, Cortese S, et al. Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. Am J Psychiatry 2013; 170: 275-289.
- Johnson M, Mansson JE, Ostlund S, et al. Fatty acids in ADHD: plasma profiles in a placebo-controlled study of Omega 3/6 fatty acids in children and adolescents. Atten Defic Hyperact Disord 2012; 4: 199-204.
- Stevenson J, Buitelaar J, Cortese S, et al. Research review: the role of diet in the treatment of attention-deficit/hyperactivity disorder–an appraisal of the evidence on efficacy and recommendations on the design of future studies. J Child Psychol Psychiatry 2014; 55: 416-427.
- Huss M, Volp A, Stauss-Grabo M. Supplementation of polyunsaturated fatty acids, magnesium and zinc in children seeking medical advice for attention-deficit/hyperactivity problems – an observational cohort study. Lipids Health Dis 2010; 9: 105.
- Hirayama S, Hamazaki T, Terasawa K. Effect of docosahexaenoic acid-containing food administration on symptoms of attention-deficit/hyperactivity disorder: a placebo-controlled double-blind study. Eur J Clin Nutr 2004; 58: 467-473.
- Manor I, Magen A, Keidar D, et al. The effect of phosphatidylserine containing omega3 fatty-acids on attention-deficit hyperactivity disorder symptoms in children: a double-blind placebo-controlled trial, followed by an open-label extension. Eur Psychiatry 2012; 27: 335-342.
- Aman MG, Mitchell EA, Turbott SH. The effects of essential fatty acid supplementation by Efamol in hyperactive children. J Abnorm Child Psychol 1987; 15: 75-90.
- Voigt RG, Llorente AM, Jensen CL, et al. A randomized, double-blind, placebo-controlled trial of docosahexaenoic acid supplementation in children with attention-deficit/hyperactivity disorder. J Pediatr 2001; 139: 189-196.
- Stevens L, Zhang W, Peck L, et al. EFA supplementation in children with inattention, hyperactivity, and other disruptive behaviors. Lipids 2003; 38: 1007-1021.
- Bélanger SA, Vanasse M, Spahis S, et al. Omega-3 fatty acid treatment of children with attention-deficit hyperactivity disorder: a randomized, double-blind, placebo-controlled study. Paediatr Child Health (Oxford) 2009; 14: 89-98.
- Raz R, Carasso RL, Yehuda S. The influence of short-chain essential fatty acids on children with attention-deficit/hyperactivity disorder: a double-blind placebo-controlled study. J Child Adolesc Psychopharmacol 2009; 19: 167-177.
- Gustafsson PA, Birberg-Thornberg U, Duchén K, et al. EPA supplementation improves teacher-rated behaviour and oppositional symptoms in children with ADHD. Acta Paediatr 2010; 99: 1540-1549.
- Johnson M, Ostlund S, Fransson G, et al. Omega-3/omega-6 fatty acids for attention deficit hyperactivity disorder: a randomized placebo-controlled trial in children and adolescents. J Atten Disord 2009; 12: 394-401.
- Arnold LE, Kleykamp D, Votolato NA, et al. Gamma-linolenic acid for attention-deficit hyperactivity disorder: placebo-controlled comparison to D-amphetamine. Biol Psychiatry 1989; 25: 222-228.
- Sinn N, Bryan J. Effect of supplementation with polyunsaturated fatty acids and micronutrients on learning and behaviour problems associated with child ADHD. J Dev Behav Pediatr 2007; 28: 82.
- Harley JP, Ray RS, Tomasi L, et al. Hyperkinesis and food additives: testing the Feingold hypothesis. Pediatrics 1978; 61: 818-828.
- Goyette GH, Connors CK, Petti TA, et al. Effects of artificial colors on hyperkinetic children: a double-blind challenge study [proceedings]. Psychopharmacol Bull 1978; 14: 39-40.
- Harley JP, Matthews CG, Eichman P. Synthetic food colors and hyperactivity in children: a double-blind challenge experiment. Pediatrics 1978; 62: 975-983.
- Levy F, Hobbes G. Hyperkinesis and diet: a replication study. Am J Psychiatry 1978; 135: 1559-1560.
- Conners CK, Goyette CH, Southwick DA, et al. Food additives and hyperkinesis: a controlled double-blind experiment. Pediatrics 1976; 58: 154-166.
- Williams JI, Cram DM, Tausig FT, et al. Relative effects of drugs and diet on hyperactive behaviors: an experimental study. Pediatrics 1978; 61: 811-817.
- Adams W. Lack of behavioral effects from Feingold diet violations. Percept Mot Skills 1981; 52: 307-313.
- Nigg JT, Lewis K, Edinger T, et al. Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms, restriction diet, and synthetic food color additives. J Am Acad Child Adolesc Psychiatry 2012; 51: 86-97.
- National Institute for Health and Care Excellence. Attention deficit hyperactivity disorder: diagnosis and management. Available at: https://www.nice.org.uk/guidance/cg72/resources/attention-deficit-hyperactivity-disorder-diagnosis-and-management-975625063621. Last updated 2016. Accessed 05 January 2017.