In the present study, family cohesion moderated the relation between free testosterone and delinquent behaviors in adolescent boys and girls. Specifically, in highly cohesive families, no association between free testosterone and delinquent behaviors was observed; whereas under conditions of low family cohesion, increasing levels of free testosterone were associated with greater delinquent behaviors among boys. The opposite pattern was observed among adolescent girls. That is, under conditions of high family cohesion, no association between free testosterone and delinquent behaviors was observed (similar to the boys), but a negative association between free testosterone and delinquent behaviors was observed among girls in low cohesion family settings. The inverse association between testosterone and delinquent behaviors in girls may be attributed, in part, to societal pressures on girls to behave in gender-appropriate ways, particularly as they approach adolescence [24
]. Indeed, our data suggest a linear negative association between delinquent behaviors and pubertal maturation (i.e. Tanner staging) in girls, which supports the proposition that, as girls get older, delinquent behaviors are viewed as inappropriate and are heavily sanctioned by society [13
Our findings parallel those reported by Booth and colleagues [12
], in which the association between testosterone and risk behaviors was conditional on the quality of the parent-child relationship. Indeed, a similar pattern of findings was reported in the earlier study, as testosterone was positively associated with risk behaviors among boys and negatively associated with risk behaviors among girls, but only among those adolescents with poor quality parent-child relations. Moreover, our findings are consistent with numerous previous studies that have reported positive family factors (e.g., parental involvement and warmth) to be predictive of lower rates of delinquent behavior during adolescence [8
]. Other studies have reported that adolescents from cohesive families, or those with close parent-child relations, are more likely to experience better self-esteem [25
], which may then decrease the likelihood of engaging in delinquent behaviors [26
In light of the cross-sectional nature of the present analyses, it is important to consider possible alternative explanations that may exist. For example, perhaps the performance of delinquent or risky behaviors leads to increases in testosterone levels among adolescent boys. Indeed early studies have reported that changes in dominance behaviors can cause changes in testosterone levels (for a review, see [27
]). Thus, one alternative hypothesis is that delinquent boys are more likely to engage in greater risk taking behaviors, which increases their testosterone levels -- and that these behaviors are also more likely to occur in the context of low cohesion homes, where parental monitoring of adolescents may be less vigilant. Because the present study did not include assessments of parenting variables, this alternative hypothesis remains to be investigated in future studies.
High family cohesion was protective with respect to delinquent behaviors, but low family cohesion was associated with aggressive behaviors among adolescent girls. A number of prior studies have underscored the critical impact of family environment on the development of behavioral problems in children [8
], and empirical data indicate that adverse conditions in the family (e.g., low family support) are key risk factors for poor adjustment outcomes [28
]. These factors may be especially relevant for girls, as studies have demonstrated that adolescent girls are generally more affected by familial factors than are boys [29
With regards to cholesterol and aggressive behaviors, LDL-C was significantly related to aggressive behaviors but only among adolescent boys. The present finding of a positive association between LDL-C and aggressive behaviors is in contrast to several previous studies that have documented negative associations between cholesterol and aggressive behaviors [30
]. On the other hand, some early studies reported that increased levels of hostility were associated with elevated LDL-C levels [31
]. In a study of participants in a cholesterol-lowering program, improvements in diet were associated with reductions in aggressive hostility and plasma cholesterol levels [32
]. More recent studies have also reported a positive association of total serum cholesterol and non-physical forms of aggression (e.g., verbal aggression, hostility) among healthy adults [14
]. In addition, total serum cholesterol was positively related to aggressiveness among college males who were not physically fit [33
], which may reflect a similar sample as the adolescent boys in the current study who presented with unfavorable lipid profiles. Finally, one study reported higher levels of aggression to be associated with higher levels of LDL-C among young adult males who had a propensity toward aggressive behavior [34
The biological pathways that may account for the association between cholesterol and aggressive behaviors have been proposed to involve stress and the catecholaminergic system [35
]. In brief, this model proposes that activation of the sympathetic nervous system during stress results in increased production of catecholamines and cortisol and elevated blood pressure, which results in elevated blood lipid concentrations. In one study, middle-aged adults displayed significant increases in LDL-C following an acute laboratory stressor [36
]. Further, exposure to chronic stress has been shown to result in greater overt aggressive responses among men, but not among women [37
]. Thus, in the context of the present study, it may be that higher levels of LDL-C reflect greater exposure to stress and that it is this stress exposure that contributes to greater aggressive behaviors among the adolescent boys. Although the proposed pathways are biologically plausible and have been empirically demonstrated in adults, comparable studies have yet to be conducted in adolescent populations and thus, our explanation for the observed association between LDL-C and aggressive behavior remains speculative. Nonetheless, the present findings highlight potential associations among lipid levels and behavioral outcomes and suggest that such relationships are gender dependent.
In conclusion, the findings from the present study contribute to the growing literature on the interactions between biological and social processes and their associations with adolescent behavioral outcomes. A key strength of the study was the ability to assess pubertal development and physical growth independently from testosterone levels. However, there are also several limitations. First, ratings of family cohesion and behavioral problems were provided by the female parent. It is possible that the mother’s ratings could have differed from the child’s perceptions. Other studies, however, have demonstrated significant convergence across family members in reports of family environment, specifically using the FES [38
]. Further, although parental characteristics could have influenced the reporting of behavioral problems, it appears that these characteristics do not lead to increased variability or changes in the relative ranking of specific problem behaviors [39
]. Second, due to the small number of adolescent girls who had reached menarche, the implications of our findings apply primarily to pre-menarcheal adolescent girls. Associations between mean levels of free testosterone and behavioral problems may differ in post-menarchal girls. Third, due to the cross-sectional nature of the data, any causal role for the interaction between biological and social factors in contributing to adolescent behavioral outcomes cannot be determined. Prospective studies involving multiple assessments of such factors over time are needed to address these key questions.
In sum, the present findings suggest that child gender and family environment moderate the association between free testosterone and delinquent behaviors in adolescent boys and girls. Because adolescent behavioral problems are early indicators of long-term risk for poor adjustment, a comprehensive understanding regarding how social factors, particularly those inherent in the family, may modify the association between testosterone and delinquency is critical. Family-centered interventions can be effective in reducing problem behaviors and can be targeted to children and adolescents in at-risk settings.