TOPIC & SIGNIFICANCE
• ADHD is the most prevalent neurodevelopmental disorder in U.S. children. 9.4% of children between the ages of 2-17 have been diagnosed with ADHD (Danielson et al., 2016). Due to its homotypic continuity, the failure of intervening at a young age may pose functional limitations and impact occupational and academic contexts throughout the lifespan (APA, 2013).
• Used by 62% of children with ADHD, stimulant medication is the most common treatment for ADHD in children (Danielson et al., 2016). Although stimulant medication temporarily normalizes dopamine availability in the brain and alleviates symptoms of ADHD (Arnsten, 2009), there is controversy surrounding its long-term effects (Mash and Wolfe, 2018). For many, ADHD symptoms continue into adulthood (Gawrilow et al., 2014). This diminishes the effectiveness of this treatment and highlights the need for an alternative intervention.
• Physical exercise (PE) has been recognized as an intervention that enhances executive functioning (EF) (Gawrilow et al., 2014), a set of processes abnormal in children with ADHD. These abnormalities constitute the core deficits of the disorder: impulsivity, hyperactivity, and inattention (APA, 2013; Mash and Wolfe, 2018).
• Understanding to which extent PE alleviates symptoms in all the three domains that constitute the disorder may offer various large-scale treatment implications that could be incorporated in school settings. PE may thus serve as a natural alternative to stimulant medication which could possess the same alleviating attributes.
METHODS
• The foundational knowledge of ADHD, its core deficits, possible treatment methods, and the efficacy of stimulant medication was acquired through the lectures of PSY1861, the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (2013), as well as Chapter 8 of Mash and Wolfe’s Abnormal Child Psychology, 7th ed (2018).
• The prevalence of ADHD was filtered out by browsing PsycInfo with the search term “ADHD Prevalence in Children”.
• Hollis’s PubMed was scanned for the “neurobiology of ADHD” and “stimulant medication” and later specified by adding “long term effects of adhd stimulant medication”.
• The initial broad search “physical activity intervention for adhd” in Google Scholar and PsycInfo yielded valuable literature reviews and meta-analyses. Gawrilow et al.’s literature review served as a starting point from which research was narrowed down with its citations. This is how the 4 empirical studies in the FINDINGS section of this poster were found.
FINDINGS
Medina et al. (2010)
• Medina et al. measured the effects of vigorous intensity PE on the inattentive deficits in children with ADHD.
• Participants ran 30 min on a treadmill, divided into 10 workouts of 2 minutes each with one minute of rest in between. Target heart rate was achieved by individualizing incline and speed of the treadmill. Conner’s continuous performance test-II (CPT) was administered afterwards, and the results of the clinical sample were compared to pre-existing data of a control sample in the database.
• Post-exercise CPT scores did not significantly differ between users and non-users of methylphenidate (MTP). Thus, cognitive effects post-CPT were not influenced by MTP. The children showed increased attention and reaction speed, and reduced impulsivity irrespective of the administration of MTP.
Pontifex et al. (2013)
• Pontifex et al. measured the impact of a single bout of PE at moderate intensity on academic achievement, neurocognition, and attention in children with ADHD.
• Participants were separated into either rest day (20 min of reading), followed by exercise day (jogging for 20 minutes on a treadmill at 65%-75% of maximum HR), or vice versa. Participants then completed an inhibitory control task (ICT) and an academic performance task while their neuroelectricity was measured.
• The healthy controls scored higher on the ICT compared to the clinical sample, though both groups scored higher postexercise. Event-related brain potential, P3, in response to the ICT was larger in the control but was increased post-exercise for both groups (Figure). Though children with ADHD showed less neuroelectricity after reading, there were no betweengroup differences post-exercise. This may give reason to claim that a single bout of PE normalized neuroelectricity and inhibitory aspects of cognitive control in children with ADHD.
• Findings suggest that physical exercise may be a prosperous nonpharmacological treatment for ADHD as it enhances attention and inhibitory control. Repeated bouts of exercise could be even more effective and succeed in improving attention and inhibitory control long-term.
Verret et al. (2012)
• Verret et al. measured the effects of a 10-week program consisting of moderate- to high-intensity PE on fitness, ADHDsymptomatology and cognitive functions including attention and response inhibition.
• Children with ADHD were split into experimental (10) and control group (11). The training program included 45 minutes of “warm-up; progressive aerobic, muscular, and motor skills exercises; and cool down” three times per week. Fitness and Motor test, and behavioral (CBCL) and neuropsychological measures were taken before and after the 10-week program.
• Children in the experimental group showed better motor performance and a higher level of information-processing postexercise intervention. They also scored significantly lower on the CBCL measures of impulsivity and showed a decreasing tendency toward inattention, though not inhibition-deficits, after the 10-week exercise program.
• The higher scores on the social scale of the CBCL post-exercise particularly highlight the possibility of incorporating PE into a treatment program for children with ADHD to improve social behavior.
Smith et al. (2013)
• Smith et al. explored the potential of a chronic PE intervention before school on ADHD symptomatology.
• 17 eligible participants engaged in 30 minutes of exercise every school day for a period of 8 weeks.
• PE consisted of small group interactive games and activities. The children completed a variety of tasks measuring cerebellar functioning, response inhibition, perceptual-organizational abilities, working memory and planning through mental manipulation. Weekly “Simon Says” and Red Light/ Green Light games also measured response inhibition.
• The motor proficiency task and shape school showed significant improvements post-exercise intervention, but ratings by parents and teachers on children’s behavior were most significant (29%-71% of the children improved in behavior).
• Thus, structured regular PE may serve as a managing tool for ADHD symptomatology because the intervention improves motor, cognitive, social, and behavioral functioning. In particular, response inhibition has consistently been shown to be improved through PE intervention.
CONCLUSIONS & FUTURE DIRECTIONS
The selected studies each explored different deficits associated with ADHD. However, combined, the studies show that PE succeeds in alleviating symptoms across all three deficit domains: Medina et al. and Pontifex et al. express the PE benefits on impulsivity. Smith et al. highlight the strengths of PE in alleviating symptoms of hyperactivity, and Medina et al. and Verret et al. reveal that the core deficit of inattention can be bettered with PE as well.
Physical Exercise HITS the SPOT!
• Future studies should measure the duration of PE benefits in alleviating symptoms in each domain to tailor an intervention that consistently alleviates symptoms
• Longitudinal studies of PE interventions may hint at PE’s lasting properties to change neural connections (e.g., Chaddock et al. found that chronic PE may increase basal ganglia volume (2010)).
• An MRI study that compares impaired brain areas of children with ADHD pre-and post a chronic longitudinal PE intervention may advance research in the field.
DREAM STUDY
BACKGROUND: Children with ADHD suffer from abnormal executive functioning in the Dorsolateral Prefrontal Cortex (DLPFC) which gives rise to the three core deficits of inattention, hyperactivity, and impulsivity. Stimulant medication is the most common treatment for children with ADHD, yet for many, symptoms persist into adulthood. Though PE has been shown to alleviate symptoms in all three deficit domains, the question remains whether PE can change faulty brain connections and improve executive functioning long-term.
OBJECTIVE: This study aims to examine the long-term effects of PE on the brain areas impaired in children with ADHD, particularly the DLPFC.
DESIGN: In a within-subjects longitudinal study design, children with ADHD will engage in 30 min of exercise daily before school as a chronic long-term intervention for two years. The children will not be administered stimulant medication. An fMRI scan will be performed pre-intervention and after two years to evaluate whether the neurobiology of the PFC may have changed. However, to formulate a causal relationship, neuroplasticity and the normal development of the brain need to be considered.
EXPECTED OUTCOME: The fMRI of the children post-chronic exercise intervention show an increased blood-oxygen-level dependent response in the DLPFC. This will manifest in an improvement of executive functioning and a reduction of ADHD’s core symptoms.
• ADHD is the most prevalent neurodevelopmental disorder in U.S. children. 9.4% of children between the ages of 2-17 have been diagnosed with ADHD (Danielson et al., 2016). Due to its homotypic continuity, the failure of intervening at a young age may pose functional limitations and impact occupational and academic contexts throughout the lifespan (APA, 2013).
• Used by 62% of children with ADHD, stimulant medication is the most common treatment for ADHD in children (Danielson et al., 2016). Although stimulant medication temporarily normalizes dopamine availability in the brain and alleviates symptoms of ADHD (Arnsten, 2009), there is controversy surrounding its long-term effects (Mash and Wolfe, 2018). For many, ADHD symptoms continue into adulthood (Gawrilow et al., 2014). This diminishes the effectiveness of this treatment and highlights the need for an alternative intervention.
• Physical exercise (PE) has been recognized as an intervention that enhances executive functioning (EF) (Gawrilow et al., 2014), a set of processes abnormal in children with ADHD. These abnormalities constitute the core deficits of the disorder: impulsivity, hyperactivity, and inattention (APA, 2013; Mash and Wolfe, 2018).
• Understanding to which extent PE alleviates symptoms in all the three domains that constitute the disorder may offer various large-scale treatment implications that could be incorporated in school settings. PE may thus serve as a natural alternative to stimulant medication which could possess the same alleviating attributes.
METHODS
• The foundational knowledge of ADHD, its core deficits, possible treatment methods, and the efficacy of stimulant medication was acquired through the lectures of PSY1861, the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (2013), as well as Chapter 8 of Mash and Wolfe’s Abnormal Child Psychology, 7th ed (2018).
• The prevalence of ADHD was filtered out by browsing PsycInfo with the search term “ADHD Prevalence in Children”.
• Hollis’s PubMed was scanned for the “neurobiology of ADHD” and “stimulant medication” and later specified by adding “long term effects of adhd stimulant medication”.
• The initial broad search “physical activity intervention for adhd” in Google Scholar and PsycInfo yielded valuable literature reviews and meta-analyses. Gawrilow et al.’s literature review served as a starting point from which research was narrowed down with its citations. This is how the 4 empirical studies in the FINDINGS section of this poster were found.
FINDINGS
Medina et al. (2010)
• Medina et al. measured the effects of vigorous intensity PE on the inattentive deficits in children with ADHD.
• Participants ran 30 min on a treadmill, divided into 10 workouts of 2 minutes each with one minute of rest in between. Target heart rate was achieved by individualizing incline and speed of the treadmill. Conner’s continuous performance test-II (CPT) was administered afterwards, and the results of the clinical sample were compared to pre-existing data of a control sample in the database.
• Post-exercise CPT scores did not significantly differ between users and non-users of methylphenidate (MTP). Thus, cognitive effects post-CPT were not influenced by MTP. The children showed increased attention and reaction speed, and reduced impulsivity irrespective of the administration of MTP.
Pontifex et al. (2013)
• Pontifex et al. measured the impact of a single bout of PE at moderate intensity on academic achievement, neurocognition, and attention in children with ADHD.
• Participants were separated into either rest day (20 min of reading), followed by exercise day (jogging for 20 minutes on a treadmill at 65%-75% of maximum HR), or vice versa. Participants then completed an inhibitory control task (ICT) and an academic performance task while their neuroelectricity was measured.
• The healthy controls scored higher on the ICT compared to the clinical sample, though both groups scored higher postexercise. Event-related brain potential, P3, in response to the ICT was larger in the control but was increased post-exercise for both groups (Figure). Though children with ADHD showed less neuroelectricity after reading, there were no betweengroup differences post-exercise. This may give reason to claim that a single bout of PE normalized neuroelectricity and inhibitory aspects of cognitive control in children with ADHD.
• Findings suggest that physical exercise may be a prosperous nonpharmacological treatment for ADHD as it enhances attention and inhibitory control. Repeated bouts of exercise could be even more effective and succeed in improving attention and inhibitory control long-term.
Verret et al. (2012)
• Verret et al. measured the effects of a 10-week program consisting of moderate- to high-intensity PE on fitness, ADHDsymptomatology and cognitive functions including attention and response inhibition.
• Children with ADHD were split into experimental (10) and control group (11). The training program included 45 minutes of “warm-up; progressive aerobic, muscular, and motor skills exercises; and cool down” three times per week. Fitness and Motor test, and behavioral (CBCL) and neuropsychological measures were taken before and after the 10-week program.
• Children in the experimental group showed better motor performance and a higher level of information-processing postexercise intervention. They also scored significantly lower on the CBCL measures of impulsivity and showed a decreasing tendency toward inattention, though not inhibition-deficits, after the 10-week exercise program.
• The higher scores on the social scale of the CBCL post-exercise particularly highlight the possibility of incorporating PE into a treatment program for children with ADHD to improve social behavior.
Smith et al. (2013)
• Smith et al. explored the potential of a chronic PE intervention before school on ADHD symptomatology.
• 17 eligible participants engaged in 30 minutes of exercise every school day for a period of 8 weeks.
• PE consisted of small group interactive games and activities. The children completed a variety of tasks measuring cerebellar functioning, response inhibition, perceptual-organizational abilities, working memory and planning through mental manipulation. Weekly “Simon Says” and Red Light/ Green Light games also measured response inhibition.
• The motor proficiency task and shape school showed significant improvements post-exercise intervention, but ratings by parents and teachers on children’s behavior were most significant (29%-71% of the children improved in behavior).
• Thus, structured regular PE may serve as a managing tool for ADHD symptomatology because the intervention improves motor, cognitive, social, and behavioral functioning. In particular, response inhibition has consistently been shown to be improved through PE intervention.
CONCLUSIONS & FUTURE DIRECTIONS
The selected studies each explored different deficits associated with ADHD. However, combined, the studies show that PE succeeds in alleviating symptoms across all three deficit domains: Medina et al. and Pontifex et al. express the PE benefits on impulsivity. Smith et al. highlight the strengths of PE in alleviating symptoms of hyperactivity, and Medina et al. and Verret et al. reveal that the core deficit of inattention can be bettered with PE as well.
Physical Exercise HITS the SPOT!
• Future studies should measure the duration of PE benefits in alleviating symptoms in each domain to tailor an intervention that consistently alleviates symptoms
• Longitudinal studies of PE interventions may hint at PE’s lasting properties to change neural connections (e.g., Chaddock et al. found that chronic PE may increase basal ganglia volume (2010)).
• An MRI study that compares impaired brain areas of children with ADHD pre-and post a chronic longitudinal PE intervention may advance research in the field.
DREAM STUDY
BACKGROUND: Children with ADHD suffer from abnormal executive functioning in the Dorsolateral Prefrontal Cortex (DLPFC) which gives rise to the three core deficits of inattention, hyperactivity, and impulsivity. Stimulant medication is the most common treatment for children with ADHD, yet for many, symptoms persist into adulthood. Though PE has been shown to alleviate symptoms in all three deficit domains, the question remains whether PE can change faulty brain connections and improve executive functioning long-term.
OBJECTIVE: This study aims to examine the long-term effects of PE on the brain areas impaired in children with ADHD, particularly the DLPFC.
DESIGN: In a within-subjects longitudinal study design, children with ADHD will engage in 30 min of exercise daily before school as a chronic long-term intervention for two years. The children will not be administered stimulant medication. An fMRI scan will be performed pre-intervention and after two years to evaluate whether the neurobiology of the PFC may have changed. However, to formulate a causal relationship, neuroplasticity and the normal development of the brain need to be considered.
EXPECTED OUTCOME: The fMRI of the children post-chronic exercise intervention show an increased blood-oxygen-level dependent response in the DLPFC. This will manifest in an improvement of executive functioning and a reduction of ADHD’s core symptoms.
