Concurrent attenuated reactivity of alpha-amylase and cortisol is related to disruptive behavior in male adolescents

Attenuated reactivity of salivary alpha-amylase has been proposed as a specific sympathetic marker of disruptive behavior in juveniles and may have additional value to studying other autonomic parameters and hypothalamic-pituitary-adrenal axis activity. Investigating the interrelationships between neurobiological parameters in relation to juvenile disruptive behavior may enhance insight into the complex mechanisms at play. We investigated salivary alpha-amylase, cortisol, heart rate (HR), and heart rate variability (HRV) in response to a standardized public speaking task, and examined interactions between these parameters in relation to disruptive behavior. Participants were 48 delinquent male adolescents (mean age 18.4 years, SD 0.9), with and without a disruptive behavior disorder (resp. DP+, DP-) and 16 matched normal controls (NC). A structured psychiatric interview as well as the Youth Self Report and Child Behavior Checklist were administered to assess disruptive behavior. Alpha-amylase and cortisol reactivity, but not HR or HRV, showed significant inverse associations with dimensional measures of disruptive behavior. Moreover, both cortisol and alpha-amylase reactivity were significantly lower in the DP + group as compared to the NC group. The mentioned relationships remained present when nicotine use was entered as a covariate. Combining alpha-amylase and cortisol in one model explained a larger part of the variance of disruptive behavior than either single parameter. There were no interactions between alpha-amylase and cortisol or HRV in relation to disruptive behavior. Attenuated alpha-amylase responsivity to stress is a correlate of disruptive behavior in late-adolescent males. Although nicotine use explains a considerable part of the variance of disruptive behavior, both alpha-amylase and cortisol are related to disruptive behavior, over and above the effect of nicotine use. Combining alpha-amylase and cortisol improved insight into neurobiological mechanisms involved with disruptive behavior; concurrent low reactivity of both parameters was related to higher levels of disruptive behavior. (C) 2012 Elsevier Inc. All rights reserved.