Adolescent Neurological Development and its Implications for Adolescent Substance Use Prevention

Barbara Lopez; Seth J. Schwartz; Guillermo Prado; Ana E. Campo; Hilda Pantin


J Prim Prev. 2008;29(1):5-35. 

In This Article

Using Findings from Studies on Adolescent Neurological Development to Design Interventions for Adolescents

Recent findings from neurological development studies (e.g., Casey et al. 2000; Luna and Sweeney 2004; Thompson et al. 2000), coupled with inconsistent findings concerning the long-term efficacy of child-centered interventions, may suggest that child-centered interventions may not be appropriate for adolescents because of the incomplete neurological development that characterizes this developmental stage. In addition, findings from long-term studies of family-based interventions suggest that an exclusive focus on family functioning may not be sufficient. Perhaps not coincidentally, there is a trend suggesting that the efficacy of child-centered and family-based interventions seem to diminish with increasing adolescent age. One possible reason for the diminished effects of child-centered interventions is that, without ongoing practice and reinforcement once the intervention has ended, the decision making skills learned in early adolescence are not retained as part of the adolescent's cognitive resources--especially as opportunities for substance use increase. Given that opportunities for substance use are often presented in socially or emotionally pressured situations, it is likely that impulsivity, sensation seeking, and an immature prefrontal cortex may preclude employing decision making skills promoted in these interventions--even if the youth does retain the skills in his or her repertoire.

Regarding family-based interventions that mobilize the context to help maintain intervention gains, it may be that a focus on family processes may be efficacious in early adolescence but not sufficient for preventing initiation of substance use in late adolescence for two reasons. First, as adolescents gain autonomy in late adolescence, keeping adolescents away from substance using situations may become an increasingly difficult task for parents. Second, in recognition that parents may not be able to keep adolescents away from all situations where substance use is possible, it is important that adolescents are exposed to instruction on decision making and are provided with a safe place (i.e., family) to practice and reinforce decision making skills. As discussed earlier, synapses that are not used are pruned during adolescence. It may be that repeated and consistent instruction in decision making about substance use, in the context of a family-based intervention (e.g., parent-child sessions to practice skills learned), may be helpful in cementing those types of decision making skills that will be useful later in adolescence and in adulthood. Indeed, findings from child-centered interventions suggest that, for repeated instruction or training in decision making to be effective, it needs to be administered in substantial doses over multiple years. These two reasons may in part be responsible for the efficacy of family-based + child-centered programs that focus on child-centered (e.g., decision making applied as related to peer resistance skills) and family-based aspects (Spoth et al. 2004, 2006). A family based intervention that improves family functioning and involves parents in promoting adolescent decision making about substance use can provide opportunities for families to practice decision making skills with their children across the adolescent years, while at the same time mobilizing the family context to protect adolescents from exposure to situations where pressure to use substances is likely to occur.

In addition to a focus on family functioning and decision making skills, it may be beneficial to include intervention components aimed at improving self esteem and feelings of self-efficacy (Swann et al. 2007). Self (e.g., self-esteem and self-efficacy) has been found to be protective against substance use (Carvajal et al. 1998; Engels et al. 2005). The inclusion of the self in interventions that address adolescent contexts such as family, school, and peers has been argued by Schwartz and colleagues (see Schwartz et al. 2005, 2007, for more extended discussions). According to Schwartz and colleagues, targeting both self and context in adolescent interventions is essential for promoting healthy development and for providing maximal protection against substance use and other problematic outcomes. The addition of components designed to improve adolescent self-esteem and feelings of self-efficacy to child-centered and family-based interventions would be an important advance in primary prevention for adolescents (Schwartz et al. in press).

Such comprehensive intervention programs can provide youth with the necessary tools and support to avoid substance use. A recent review by Nation et al. (2003) supports the use of more comprehensive prevention programs for substance use as well as for other problem behaviors in adolescence. Both internal resources and external context are important, given that decisions about whether to engage in substance use often take place in emotionally charged situations. Family-based components targeting monitoring and supervision, as well as the parent-child closeness and bonding that prompts adolescents to disclose their plans and whereabouts to their parents (Kerr and Stattin 2000; Stattin and Kerr 2000), may be important in decreasing the likelihood that the adolescent will be exposed to substance using situations. In a program combining family-based and child-centered intervention strategies, parents might be enlisted, for example, in helping adolescents to develop a coherent self-concept or identity and learn to make good decisions and how to handle emotionally charged and high-risk situations. Indeed, self-concept or identity has been found to mediate the relationship between family functioning and adolescent problem behavior (Schwartz et al. 2005, 2006). Additionally, family support, encouragement, and protection may provide an added safety net for adolescents when they are faced with emotionally laden and difficult decisions, which they may not be cognitively ready to negotiate successfully (Reyna and Farley 2006; Steinberg 2007).

Some research has begun to move in this direction. Recent innovations in family-based interventions have lead to more comprehensive designs that include both parent and child components targeting family functioning and decision making (e.g., ISFP: Molgaard and Spoth 2001; LST + SFP10-14: Spoth et al. 2002, 2005) as well as components that target more distal adolescent contexts such as peers, school, and neighborhood (e.g., Familias Unidas: Pantin et al. 2003; Say Yes First: Zavela et al. 2004). These interventions are thought to be efficacious because they address risk factors across domains of functioning for the adolescent (e.g., intrapersonal, peer, family, and school; Hawkins et al. 1992; Kumpfer 1997). However, evaluations of the efficacy of most of these programs for preventing adolescent substance use in the long term are not yet available.

Despite mounting evidence that neurological development influences decision making in adolescence, there are only a few researchers who have begun to use the findings from the neurological literature to refine and develop preventive interventions for adolescent substance use (e.g., Fishbein et al. 2006). The evidence for a link between neurological development and decision making, as well as the paucity of research in this area, presents an important opportunity for researchers to examine several aspects of this link. As a result, a number of opportunities for further research follow from the present review.

As discussed earlier, initial results from long-term follow-ups are promising, particularly for family-based + child-centered interventions. We suggest that family-based + child-centered interventions that are administered to both parent and child may be more efficacious than either type of intervention alone in preventing adolescent substance use in the long term, for three reasons. First, family-based + child-centered interventions produce changes in family functioning (e.g., increase parental monitoring and parent child communication) that, in turn, decrease the likelihood that the adolescent will be exposed to substance using situations, thereby reducing risk for substance use appropriate (Lochman and van den Steenhoven 2002). Second, family-based + child-centered interventions do not rely solely on the decision making abilities of the adolescent, which may be impaired due to immature neurological development, to decrease likelihood of substance use. Third, family-based + child-centered interventions provide the adolescent with a context to reinforce and develop decision making skills. Although initial long-term follow-up results of family-based + child-centered interventions are promising, it is important to replicate these findings in other samples to draw a more definitive conclusion.

Age Differences in Intervention Efficacy

In addition to examining the longer-term efficacy of interventions, it is also important to examine age differences in intervention efficacy. It may be that certain components or types of interventions may be more efficacious with certain age groups. For example, family based interventions may be more effective in younger adolescents because they do not rely on decision making ability, whereas interventions that focus on decision making may be more efficacious in emerging adults--presumably because of their maturing decision making abilities. A meta-analysis of existing interventions, examining age as a moderator of intervention efficacy, would be useful to shed light on this issue.

Executive Cognitive Functioning as a Moderator of Intervention Efficacy

It is clear that not all interventions work equally well for all participants. This is partly due to individual differences in cognitive, social, and emotional development. Identifying which interventions work best for whom is an important task for prevention researchers--and neurological development and decision making may hold important implications for addressing this question. We suggest that further research is needed, specifically studies examining intervention efficacy while controlling for individual differences in cognitive ability. Researchers such as Fishbein et al. (2004, 2006) have begun to examine the role of executive cognitive functioning in intervention efficacy. Indeed, Fishbein et al. (2004) found that executive cognitive functioning or decision making ability was associated with response to interventions. These results are preliminary given the small sample size. However, if replicated, these results have the potential to help differentiate youth who will respond to universal primary preventive interventions from youth who may need more comprehensive interventions (Paschall and Fishbein 2001).

Longitudinal Studies of Neurological Development and Executive Cognitive Functioning

Despite evidence from clinic studies supporting the link between neurological development and adolescent decision making, little is known about neurological developmental processes outside of the laboratory setting. Longitudinal investigations of the link between neurological development and adolescent decision making are needed. From a prevention research perspective, longitudinal studies would be useful to answer at least three questions: (a) At what ages or age range has neurological development advanced to the point that it is able to support rational decision making, even in emotionally charged situations? (b) Does the effect of environmental factors on decision making vary across development? (c) How do individual differences in neurological development, as well as in patterns of change over time in decision-making skills, and emotion regulation, influence behavioral outcomes (risk taking, substance abuse, etc.)?

Examining Gender and Ethnic Differences in Neurological Development and Executive Cognitive Functioning

The prevalence of substance abuse in adolescence has been found to vary by ethnicity as well as by gender (Johnston et al. 2006a). For example, 8th and 10th grade Hispanic adolescents have higher alcohol and drug use across all classes of drugs (with the exception of amphetamines) than African American and non-Hispanic White youth (Johnston et al. 2006a), and boys tend to have higher rates of illicit drug use than girls. Gender differences have also been examined in decision making with mixed results (Blair et al. 2001; Crone et al. 2003; d'Acremont and Van der Linden 2006; Ernst et al. 2003). Three of the four studies did not find gender differences in decision making (Blair et al. 2001; Crone et al. 2003; Ernst et al. 2003). On the other hand, d'Acremont and Van der Linden found that adolescent boys make more risky decisions than adolescent girls. With respect to ethnic or gender differences in neurological development, no studies were found that examined ethnic differences. However, there is some evidence from fMRI studies that gender differences may exist in the brain's organization and activation during the maturation period (Durston et al. 2001; Killgore et al. 2001). Results from a longitudinal fMRI study suggests that the pruning process in the frontal lobe is delayed in boys (Giedd et al. 1999) and different patterns of neurological development or activation, especially in the prefrontal cortex, may provide a plausible explanation regarding gender differences in decision making. Although our search yielded no studies that examined ethnic or gender differences in the link between decision making ability and substance use, the available evidence suggest that it is possible that such differences exist. Examination of these differences would be beneficial in advancing our knowledge concerning neurological development and for tailoring preventive interventions to specific populations.


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