This paper was supported by grants from the National Institute on Drug Abuse (No. DA13814, DA016090, DA020138, and P50 DA16094).
Schools are an efficient and convenient choice of setting for intervention programs targeting adolescents. Schools provide access to a large number of adolescents in a learning environment in which adolescents are more likely to be receptive toward instructions involved in an intervention. Moreover, monitoring the fidelity of program implementation and assessing program effectiveness in a school setting are relatively easy. In addition, the typical 4-year structure of school systems is conducive to tracking down students in order to obtain long-term follow-up data.
Prevention programming attempts to reach adolescents prior to the expected occurrence of certain problematic behavior such as drug abuse. The central focus of prevention is on the antecedents of problem behavior. Program participants are taught how to anticipate the impacts of these antecedents (e.g., such as desiring to feel good, cognitive exposure to drug-related cues, social influence, or cultural norms) and to counteract their potential impacts with instruction of protective cognitions, behaviors, or access to protective social units (e.g., drug-free communities). Among these strategies are selective or indicated approaches that attempt to prevent individuals who are either currently at-risk for drug use behavior, by virtue of their membership in certain segments of the population, or who are already demonstrating early signs of drug use behavior, from developing clinically diagnosed drug use disorders. Some researchers tend to refer to both indicated and selective programs as targeted programs.
Cessation (treatment) programs are designed to assist in stopping drug use, given that youth were either not exposed or did not respond to prevention efforts. Cessation programs provide participants with strategies to cope with psychological dependence (emotional reliance) on and physiological withdrawal from a drug (e.g., what types of withdrawal symptoms to expect, how long one will experience these symptoms, and how to cope with these symptoms without relapsing). Cessation programs focus on stopping a current behavior from continuing to arrest ongoing consequences and permit recovery of health. The goal may also involve teaching one how to live with permanent changes (e.g., drug-related injury).
In the school setting, prevention efforts are generally delivered school-wide (i.e., universal prevention), whereas cessation programs are usually delivered outside of the classroom (e.g., with student assistance programs, in clinics, or perhaps involving the school nurse, possibly involving self-help support groups, which meet during lunchtime or after school). Exposure to early prevention programming could provide proactive interference against later drug-facilitative–type information, resulting in protection against drug misuse. These prevention efforts may inhibit, delay, or halt addiction, which is what makes cessation so difficult. For older adolescents who are caught up in cycles of drug misuse or abuse, prevention programming could help minimize the time spent in a using cycle.
A recent focus of adolescent school-based drug abuse prevention and cessation programming involves applying models of neurobiology/neuropsychology as potential influences on program outcomes. This chapter provides a brief overview of the application of neuroscience to adolescent development, indicates current school-based prevention and cessation strategies that may impact neuroscience-relevant adolescent functioning, and suggests new directions for the development and implementation of drug use prevention and cessation programs.
Brief Overview: Neuroscience and Adolescents
Adolescent vulnerability to substance use has been associated with the protracted morphological development of the neural systems responsible for self-control and regulation, in conjunction with a heightened tendency to seek novel experiences (e.g., Steinberg and Chambers et al. ). The regions of the human brain linked to self-control and self-regulation are not fully developed until late adolescence. However, an increase in novelty-seeking behavior is evident when children transition into early adolescence. Thus increases in risk-taking and sensation-seeking tendencies among adolescents seem to precede the development of self-regulatory competencies.
Several animal as well as human studies suggest that novelty-seeking behavior increases rapidly during adolescence ; this has been attributed to the changes that occur in the pro-motivational dopamine systems during this stage of ontological development. The level of dopamine turnover among adolescents is likely to be higher than among children and adults. Dopamine in the ventral striatum, which includes the nucleus accumbens, is believed to modulate the conversion of thoughts and emotions into motivated actions. Dopamine release in the nucleus accumbens appears to filter and gate the motivational signals received from the cortical and limbic systems that are to be processed by the downstream motor systems.
Several motivational stimuli have been associated with dopamine stimulation in the nucleus accumbens, including the drugs of misuse and agents of natural reward (e.g., food, sex). Furthermore, novel experiences tend to cause higher levels of dopamine stimulation compared with previously learned behaviors that have expected outcomes. Hence, the same mesolimbic dopamine systems appear to mediate both drug- and novelty-seeking behaviors. Conversely, concentrations of inhibitory motivation neurotransmitters such as serotonin appear to be lower in adolescent cerebrospinal fluid, which has been associated with higher impulsivity. A greater tendency to act along with decreased inhibitory tendencies for self-destructive action could contribute to drug use experimentation.
Adolescents’ vulnerability to drug use due to developmental changes in the dopaminergic system is further exacerbated by the relatively underdeveloped prefrontal cortex. Brain structure and function undergo significant changes throughout adolescence, notably in the forebrain regions, which comprise the prefrontal cortex. The prefrontal cortex is one of the last cortical structures to reach full ontogenetic development and may not achieve complete maturation until the third decade of a person’s life. This region of the brain is responsible for the spatiotemporal organization of goal-directed actions, which involve the carrying out of relevant actions in response to internal (e.g., memory) or external (e.g., environmental context) cues. In other words, the principal function of the prefrontal cortex is to perform executive function. Executive function represents a complex set of interrelated functions that make the temporal organization of goal-directed behavior, language, and reasoning possible. Methodologically, brain researchers find it difficult to separate the interrelated components of the executive system into discrete units (e.g., attention, working memory, decision-making) and localize them to specific areas of the prefrontal cortex. For example, the functional contribution of a specific prefrontal cortex area is difficult to measure after a discrete lesion, for such a lesion is likely to functionally affect the entire executive system. Nonetheless, researchers have linked deficiencies in executive function to abnormalities related to attention, working memory, long-term memory retrieval, planning, temporal integration of memory and goal, decision-making, monitoring, and inhibitory control.
Ability to exert sustained attention or manipulate the focus of one’s attention is necessary to formulate a goal-directed thought or bring an action to completion. In turn, one needs to control distracting or interfering urges, both internal (e.g., thoughts, memory, instinctual) and external (e.g., environmental), in order to maintain sustained attention. Working memory refers to the ability to retain information and utilize the information to execute a related action. Like most executive functions, working memory and sustained attention are interrelated and are essential for task perseverance. Furthermore, execution of actions involves foresight and planning. Planning represents the ability to utilize information obtained from selective retrieval of long-term memory, such as memory of past actions, for the anticipation of future events. Planning provides a conceptual scheme for the execution of a goal-directed behavior, and based on the anticipation of consequences, lays out the order of prospective actions. Individuals often have to choose among competing actions. The executive function of decision-making involves choosing an action after rationally evaluating the potential risks and rewards associated with its outcomes. Successful execution of goal-directed behaviors also depends largely on the ability to self-monitor. Monitoring enables one to assess the discrepancies between one’s actions and one’s goals, thus creating feedback which allows one to correct subsequent actions.
Inhibitory control involves controlling an impulse by inhibiting a response. According to Barkley, response inhibition involves three processes: (1) inhibition of the prepotent response (i.e., a response linked in associational memory to immediate reinforcement), (2) stopping of an ongoing response in order to delay the final decision to respond, and (3) protecting this decision-making time interval from being interfered with by other competing stimuli and responses (i.e., interference control). Primary response inhibition partially aids the functioning of working memory, regulation of motivation, verbal internalization, and behavioral analyses.
Hence executive functions make the self-regulation of thoughts, emotion, and behavior possible. Conversely, deficiencies in executive function may result in poor impulse control, poor judgment, and disinhibited behavior. Among adolescents, poor executive functioning has been consistently associated with higher rates of drug use (e.g., Grekin and Sher, Mezzich et al., Tarter et al., and Xiao et al. ). Furthermore, early adolescent deficiencies in executive function have been found to predict later drug use disorders. For example, Habeych et al. found that attenuated amplitude of the P300 wave, an indicator of executive cognitive function, in late childhood predicted substance use disorders in late adolescent males.
Research suggests that executive function develops in sophistication at the same rate as the structural maturation of the prefrontal cortex; and age-related social and cognitive maturation during adolescence may be attributed to the concomitant structural changes in the brain. For example, improvements in planning and decision-making have been linked with the structural developments in the dorsolateral and ventrolateral prefrontal cortex, respectively. Most notable developmental changes in the forebrain region have been observed as changes in gray and white matter volumes. Recent neuroimaging studies suggest that there is a continuous increase in the brain white matter volume during adolescence. For example, a significant growth is noticed in the posterior corpus callosum, the collection of over 200 million nerve fibers that allow communication between right and left hemispheres of the brain. In addition, the gray matter volume, which increases substantially during childhood, appears to decrease during adolescence in certain cortical structures (e.g., the prefrontal cortex ).
Reduction in cortical gray matter volume might occur due to increased intracortical myelination and/or due to synaptic pruning. Increased myelination of neurons results in a more efficient propagation of action potentials. Synaptic pruning involves selective removal of synapses that “do not efficiently transmit information pertaining to accumulating experience.” Synaptic pruning appears to serve a number of functions that facilitate cognitive development. For example, the process appears to stabilize the firing patterns of cortical neurons, which in turn is thought to enhance working memory performance. In general, both myelination and synaptic pruning are believed to enhance the efficiency of cortical information processing as well as the connectivity between cortical and subcortical regions.
Thus because adolescent prefrontal cortex is not yet fully developed, the associated executive functions are expected to be inadequately developed. As a result, adolescents tend to have lower regulatory competence, which makes them highly susceptible to drug use risk factors such as rash impulsiveness and poor decision-making. For example, adolescents tend to be poor judges of the harmful consequences of drug use, yield easily to peer pressure, and seek immediate gratification. Therefore it is not surprising that most adult drug users are likely to have initiated drug use in the period between early to mid-adolescence, before the brain regions associated with self-regulation are optimally developed.
In summary, evidence suggests that the developmental upsurge in novelty seeking coupled with suboptimal brain development makes adolescents vulnerable to drug use. Thus to some extent, adolescent experimentation with drugs appears to be a normative behavior. However, it should be noted that individual differences exist among adolescents with respect to both novelty seeking and executive functioning; some adolescents are always at a higher risk for developing substance use disorders than others.
Negative Consequences of Drug Use on Teen Cognitive Function
Early onset of drug use, escalation of use, and possible dependence might subject adolescents to the risks of developing mental health disorders and experiencing social, academic, and legal consequences. The developing adolescent brain appears to be highly vulnerable to the neurotoxic effects of drugs, including those of licit drugs such as tobacco and alcohol and the so-called soft drugs such as marijuana. Prolonged exposure to drugs during adolescence may result in neuropsychological deficiencies and structural brain damage, especially in areas associated with memory and executive function. Brown et al. have reported that compared with a matched group of healthy youth, alcohol-dependent young adolescents (in the third week of abstinence) were found to perform poorly on verbal and visuospatial tasks, suggesting that protracted exposure to alcohol might have enduring adverse effects on the brain’s functional ability involving memory and information processing. In fact, magnetic resonance imaging results indicate that youth with alcohol use disorders tend to show smaller hippocampal and white matter volumes and smaller prefrontal cortices. De Bellis et al. further found that the total hippocampal volume among adolescents with alcohol use disorder increased with the age at onset and decreased with the duration of disorder.
Although, taken together, the relatively limited extant neuroimaging studies fail to conclude whether chronic marijuana use is related to structural abnormalities in the brain (for review, see Quickfall and Crockford ), some of the findings (e.g., Wilson et al. ) suggest a relationship between age at first onset and decreased total brain volume. Furthermore, it appears that early marijuana use initiators (e.g., before the age of 17) tend to show significant later cognitive deficits (e.g., indicated by verbal IQ; visual scanning tasks) in comparison with nonusers and late-onset users . , Nicotine-dependent adolescents have been suggested to perform normally on working memory tasks following nicotine intake but poorly during withdrawal. One neuroimaging study indicated that despite poor task performance, nicotine-dependent adolescents on withdrawal exhibited increased activities in the prefrontal cortex regions (e.g., dorsolateral prefrontal cortex) associated with working memory. Because an optimal level of dopamine action is essential for normal working memory functioning, the adverse effects of tobacco use cessation on working memory suggest that regular nicotine use causes abnormal adaptations of the dopaminergic circuitries. In fact, research on rodents has shown that the normal development of catecholaminergic systems during adolescence might be disrupted by protracted exposure to nicotine. These studies have linked adolescent nicotine exposure with hippocampal damage and impairments in the midbrain catecholaminergic systems that play important roles in mood regulation and addiction development.
By adversely affecting the normal development of the cortical and limbic brain structures associated with risk and reward calibration, decision-making, and inhibitory control, drug use not only exacerbates the loss-of-control due to incentive-sensitization but also undermines the cognitive ability to stop using drugs voluntarily. Evidence suggests that drug addiction might be related to impairments in ventromedial prefrontal and anterior cingulate cortices, brain regions associated with decision-making and inhibitory control. Furthermore, acute withdrawal of drug use seems to affect the anterior cingulate cortex, consequently weakening inhibitory control.
However, it should be noted that most of the research linking adolescent drug use, drug use withdrawal, and neuropsychological deficiencies has been cross-sectional, which makes any conclusion on their causal relationships open for debate. Nonetheless, it seems that deficient neuropsychological functioning and adolescent drug use share a reciprocal relationship. For example, neuropsychological deficiencies in preteen years tend to predict drug use disorders (e.g., Tarter et al. ), and, similarly, early drug use onset or abuse also seems to predict neuropsychological deficiencies. Such bidirectional relationships imply that adolescents with impaired neuropsychological functioning face the additional risk of drug use–mediated further neuropsychological deterioration.
Thus there appear to be at least three important reasons that prevention or treatment targeting adolescent drug misuse should address motivation, decision-making, and inhibitory control. First, adolescents normally tend to show suboptimal development of regulatory competence. Second, this regulatory competence is likely to be markedly lower among drug-misusing adolescents due to possible impairments in certain brain regions such as the prefrontal cortex, anterior cingulate cortex, and hippocampus. Poor regulatory competence may not only make it difficult for these high-risk adolescents to stop using drugs but may also cause them to relapse easily in case of temporary successful cessation. Third, adolescents at high risk for using drugs or developing drug use disorders are already likely to rank low on neurobehavioral inhibition, which might additionally indicate that their executive functions have trait-based deficiencies. Thus drug-abusing adolescents and adolescents at risk for developing drug dependence would benefit greatly from supplemental programming that promotes adaptive coping, impulse control, problem solving, and self-monitoring.
Brain Development and School-Based Drug Use Prevention and Treatment
It has become increasingly important for prevention researchers to take into account the findings made in neuroscience to guide their approach in designing drug use prevention programs for youth. In particular, researchers are interested in knowing whether developmental neurobiological and neurocognitive variables moderate and/or mediate prevention effects. Currently, the research attempting to answer these questions seems to be at a preliminary stage. For example, there is some evidence that adolescents’ neurocognitive skills moderate their response to preventive intervention materials. In a study dealing with social competency skills training, adolescents with poor executive cognitive abilities were less likely to respond positively to the prevention curriculum. Hence not all youth may be equally able to process prevention messages and instructions, and program materials may need to be individualized to address differential neurocognitive skills.
Alternatively, prevention or treatment programs may aim to enhance adolescent neurocognitive skills in order to counteract drug use behavior. Recent evidence suggests that practice in tasks requiring regulatory skills may enhance one’s executive functioning, and this alteration appears to correspond to practice-induced structural changes in the brain (e.g., Kabat-Zinn and Quickfall and Crockford ). Hence one might argue that repeated practice of skills and tasks demanding the use of executive functions (e.g., attention control, working memory) during childhood and adolescence, when cortical structures are likely to be most malleable, may assist the age-related development of executive functions, and in turn protect adolescents from engaging in risky behaviors.
Need for Tailoring Prevention and Treatment Programs
To promote program efficacy, prevention and treatment programming may need to be tailored to participants’ personality characteristics. For example, outcomes may be enhanced a great deal if programs are designed to permit maximum processing of information by sensation-seeking recipients with neurocognitive processing that prefers presentations of rapidly changing stimuli. As noted by Bardo et al., novelty exposure tends to activate the same neural substrates that mediate the rewarding effects of drugs of abuse. The reinforcing effects of drugs play a key role in promoting continued drug use behavior, especially among individuals who are more susceptible to drug effects (e.g., sensation-seeking or novelty-seeking individuals). Initial positive or neutral physical responses to drugs may encourage subsequent use, whereas initial aversive physical reactions may discourage subsequent use behavior. One suggestion for prevention is to consider that at-risk youth (e.g., sensation-seeking youth) may process information differently than lower risk youth, and therefore prevention materials should be tailored accordingly.
Given the evidence that individuals higher in sensation seeking may have a neurobiologically based need for stimulation, it seems reasonable to assume that they need drug abuse prevention messages that are novel and exciting enough to grab their attention and pique their curiosity (e.g., see Pentz et al. ). In fact, Palmgreen et al. found that high-sensation-seeking value-type public service announcements may have influenced higher sensation seekers’ drug intake for several months following a media campaign. Fast-paced, novel, and stimulating media-type programs that grab or increase adolescents’ attention and learning may more effectively influence sensation-seeking individuals with lower baseline dopamine turnover.
Staiger et al. have recently stated the need for tailoring drug abuse treatment programs with respect to three specific personality-based drug use risk factors, namely, reward sensitivity, behavior disinhibition (or rash impulsivity), and anxiety proneness. For example, contingency management could be used as a possible tactic for someone with high levels of reward sensitivity, as to replace drug-related reward with a prosocial alternative. Similarly, treatment strategies such as meditation and mindfulness-based practices could be used to promote attention control and relaxation in order to address impulsiveness and anxiety proneness, respectively.
Current School-Based Prevention Practices and Executive Functions
School-based programs designed for young children often focus on improving social-emotional competence (e.g., Greenberg et al., Shure, and Shure ). Temperament characteristics such as emotionality predict adolescent problem behavior, including drug use behavior. Wills and colleagues argue that a person’s childhood temperament characteristics and socialization affect his or her ability to self-regulate during adolescence, and in turn, his or her drug use behavior. Promoting Alternative Thinking Strategies is a school-based prevention program that attempts to assist young children in social and emotional learning through the teaching and practice of executive function skills. The Promoting Alternative Thinking Strategies curriculum is based on the affective-behavioral-cognitive-dynamic model of development. The assumption underlying the affective-behavioral-cognitive-dynamic model is that due to delayed development of the neurocircuitry connecting cortical and limbic structures, children’s cognitive and linguistic development tends to be inadequate when required to regulate complex emotional experiences. Thus children appear to have difficulty verbally internalizing emotional experience and managing related behavioral response. The Promoting Alternative Thinking Strategies curriculum uses the concepts of vertical control and horizontal communication to assist children’s age-related neurocognitive development. Vertical control refers to the exertion of control by higher-order cognitive processes on the lower-order limbic impulses, and horizontal communication refers to mediated communication between the two hemispheres of the brain, a process integral to the internal verbalization of affect.
Results demonstrate that Promoting Alternative Thinking Strategies can improve vertical control and horizontal communication. Vertical control is addressed though the combined use of curriculum lessons and the Control Signals Poster, which teach strategies for self-control, such as self-talk, that facilitate inhibitory control and planning. The control signals poster uses a traffic-signal to guide goal-directed behaviors (e.g., red light signaling to stop and calm down, yellow light to slow down and think, and green light to try out the plan ). Horizontal communication is addressed through the identification and labeling of emotions and feelings through the combined use of curricular lessons and Feeling Face cards, which include color-coded facial images of affective states.
A Promoting Alternative Thinking Strategies trial involving 7- to 9-year-olds recently found that the curriculum was effective in reducing externalizing and internalizing behaviors at 1-year follow-up, that Promoting Alternative Thinking Strategies had significant positive effects on verbal fluency and inhibitory control nine month posttest, that both inhibitory control and verbal fluency partially mediated internalizing behaviors, and that inhibitory control partially mediated the program effects on externalizing behaviors.
Another example of a program for young children that focuses on social and emotional learning is the I Can Problem Solve program. This program has been implemented on preschoolers through sixth graders and provides children with language and critical thinking skills that help them successfully resolve interpersonal problems with peers and adults through effective decision-making. The program is recommended to be implemented as a daily 20-minute classroom session for 15 months. All sessions are designed to foster interpersonal cognitive problem solving through dialogues, games, and group discussions that involve the use of words, pictures, puppets, and role playing. For example, students are taught to identify words that are precursors to understanding behavioral consequences and problem solving, and teacher-initiated interpersonal cognitive problem-solving dialogue is used to solve actual interpersonal problems among children. The program has been successful in reducing impulsivity and social inhibition (e.g., fear and timidity of others), which are related to the development of drug use and mental health disorders.
Although it is common for prevention programs to include cognitive-behavioral skills training as a major component (e.g., life skills training), executive function variables are not often directly measured as mediators of program effects. However, in essence, such studies attempt to enhance the rate and quality of age-related cortical development. Several developmentally tailored life skills training trials have been successfully implemented in elementary, middle, and high schools to develop social and personal skills among youth. The skills-building component of the program focuses on developing regulatory competence among youth necessary to counteract the social influences of drug use through training on, for example, coping and anxiety management (e.g., vertical control), and effective communication and assertiveness (e.g., horizontal communication).
Recently, mindfulness-based interventions have emerged as having promising implications for executive function enhancement, with the potential to be applied to school-based drug use prevention. Mindfulness refers to attaining a mental state in which attention is sustainably focused on the nonjudgmental awareness of thoughts and sensations passing through one at the given moment. Mindfulness interventions train participants to control their attention and emotions so as to focus on the present moment. Essentially, mindfulness interventions provide training in self-regulation. Typically, mindfulness-based interventions use a simple sitting technique that teaches participants to focus on the breath, image, or mantra for as little as 10 minutes per session. Since 2005, a number of studies have demonstrated that mindfulness training provided to children and adolescents may result in improved working memory, attention, and emotional regulation. For example, researchers have used task performance–based measures of executive function to show the effects of mindfulness-based interventions on improved working memory, attention-control, and cognitive flexibility among elementary school students.
The majority of mindfulness-based intervention studies involving adolescents have been school-based. A recent systematic review by Felver et al. identified 28 empirical studies that evaluated school-based mindfulness interventions for adolescents. Sixteen of the 28 studies involved a control group. In general, the studies tended to show that mindfulness intervention was associated with decreased externalizing and internalizing behaviors and mental health symptomology including anxiety, depression, and suicidal ideation. Although none of the studies assessed substance use as an outcome, the findings that mindfulness can modulate executive functions and reduce the more proximal risk factors of adolescent drug use such as externalizing behavior are very promising in regard to the successful application of mindfulness in school-based drug use prevention. Preliminary research on adolescent mindfulness and adolescent drug use is promising. For example, Pentz et al. found trait mindfulness to buffer the effects of risk factors on adolescent drug use. Another study showed that higher trait mindfulness was associated with reduced adolescent drug use through lower negative affect and lower perceived stress.
Clearly, more research is needed to better understand the potential protective effects of mindfulness-based interventions on executive functions and adolescent drug use. Even though a few studies have examined the effects of mindfulness on adolescents’ executive functions as assessed with performance tasks, most school-based research still rely on self-reported measures as outcomes of mindfulness-based interventions. Despite their merits, self-report measures may not be ideal to assess changes at the neurocognitive level. In addition, more research is needed to test hypothesis related to neurocognitive mechanisms that underlie the relationship between mindfulness and adolescent drug use.
It appears that prevention programming would benefit additionally from the inclusion of a motivation component. Sussman et al. evaluated 29 evidence-based, targeted drug abuse prevention programs for their effects on drug use or other problem behavior among high-risk youth. Eighteen of these programs involved school as a setting in some way. Of the 18 programs, 12 involved some motivation aspect, generally motivation enhancement, but sometimes they included extrinsic reinforcement strategies (i.e., reinforcement by manipulating environmental consequences of behavior such as by being paid contingent on performance). Sixteen of the 18 programs provided skills training, and 11 programs provided instruction in decision-making.
Taken together, these programs appear to define a type of programming referred to as the Motivation-Skills-Decision-making Model. According to this model, targeted programming needs to: (1) motivate the at-risk recipients, who might have higher reward sensitivity, to not desire to misuse drugs; (2) teach skills to enhance regulatory competence (e.g., self-control strategies ) and form prosocial bonds; and (3) facilitate decision-making and goal-directed behaviors. The Motivation-Skills-Decision-making Model tends to appear in a majority of the 18 programs; however, all three components were included together in only 5 of the programs.
The Reconnecting Youth program was one of the five programs and was implemented to youth at risk for school dropout. The program involved 90 sessions within a comprehensive high school class, delivered generally over one semester, with small student groups and highly trained teachers. Instruction included use of group support and providing life skills training (norm setting, self-esteem enhancement, mood management, communication skills, self-monitoring, monitoring goals, school bonding, and social activities), with feedback to parents. Program goals were achieved through use of a quasi-experimental design, showing effects for school performance (18% improvement in grades), drug use (54% decrease in hard drug use), and suicide risk (32% decline in perceived stress). This program involved all three components of the Motivation-Skills-Decision-making Model, except that motivation was provided through peer group support, not through provision in motivational enhancement strategies. In essence, these targeted programs for high-risk populations could be interpreted as modifying phenotypical expressions of suboptimal neurobiological development. However, future integrative research will be needed to examine the reality of this speculation.