The goal for the proposed approach of secondary preventive interventions is to reduce the likelihood of the emergence of ADHD and to slow its escalation in severity or persistence from its earliest manifestations by facilitating brain growth and development. This, in turn, should minimize many long-term complications typical of ADHD. Central to successful implementation of this approach is the notion that early identification is possible. While undoubtedly some children will be missed, for the most part, irrespective of whether the child meets full diagnostic criteria for ADHD, symptoms of hyperactivity and impulsivity are evident during the preschool years in most children who go on to develop the disorder. With increased rates of attendance at daycare and preschool over the past 2 decades [97
], early identification of “at-risk” preschoolers should be easier than ever.
The fact that at-risk children who will not develop ADHD might also be identified and treated requires these interventions to be noninvasive, relatively low in cost, readily accessible, and easy to implement. Widespread use of preventive interventions targeting at-risk children would not only need to remain relatively risk-free, but, to the extent that it is possible, they should also be helpful to all children irrespective of at-risk status. In this regard, engaging in challenging and cognitively stimulating games should be enjoyable and growth-promoting, even in typically-developing children. With regard to cost, accessibility, and ease of implementation, several emerging programs [94
] use a group-based approach that is overseen by a professional, but can be delivered largely by paraprofessionals and/or trained students, thus substantially lowering costs. In addition, the clinical setting might not be ideal for administering these interventions, which often require large playrooms for child groups. Rather, schools and community centers might be better suited, making the intervention accessible to large numbers of individuals. As for ease of implementation, it will be critical that these programs be highly palatable both to parents and children (and perhaps teachers) in a manner that will engage them in the intervention in an ongoing and meaningful way.
Early interventions for children at high risk for developing an array of difficulties other than ADHD have received attention over the past few decades. Such programs as Perry Preschool and the Abecedarian Project, as well as Head Start, have been shown to help shift the oftentimes poor trajectories associated with residence in high-poverty communities [98
]. These relatively brief early intervention programs have been shown to alter educational, occupational, and criminal outcomes for vulnerable youth. As depicted in Fig. , small changes to the trajectory of ADHD during the preschool years have the potential to yield very substantial benefits across the lifetime of a child. Figure depicts the developmental course of ADHD, with decreasing prevalence and symptom severity associated with later phases in development. As shown in Fig. , relatively modest changes in early childhood have the potential for substantial impact over the lifespan.
Fig. 2 Depiction of the developmental course of attention-deficit/hyperactivity disorder (ADHD) symptoms across the lifespan of children and the potential impact of early intervention on long-term symptom trajectories. The shaded area reflects the number of (more ...)
In summary, ADHD is a neurodevelopmental disorder, the symptoms of which often emerge during the preschool years. Substantial animal and human research has provided evidence that environmental stimulation and exercise can impact the developing brain. Early childhood is a critical period for brain development, and early intervention may be crucial for addressing an array of neurodevelopmental disorders, including ADHD. Intervention at an early age, by which ADHD can be detected, but prior to the emergence of many of the more chronic and impairing comorbidities and associated features that result in poor long-term outcome, may also be critical to altering the common course of lifelong impairment. Although correlational in nature, there is evidence to suggest that maturation of the brain and related improvements in neuropsychological functioning may translate into reduced ADHD symptom severity and impairment. Importantly, recent data from clinical trials demonstrate preliminary evidence that intervening early in ADHD can have persisting efficacy beyond the termination of active treatment. Longer term follow-up data from randomized controlled trials, in combination with neuroimaging pre- and post-treatment, will be a critical test of whether the interventions are in fact capable of altering the brain and truly shifting the course of the disorder.