Heterogeneity in the development of proactive and reactive aggression in childhood: Common and specific genetic - environmental factors

BackgroundFew studies are grounded in a developmental framework to study proactive and reactive aggression. Furthermore, although distinctive correlates, predictors and outcomes have been highlighted, proactive and reactive aggression are substantially correlated. To our knowledge, no empirical study has examined the communality of genetic and environmental underpinning of the development of both subtypes of aggression. The current study investigated the communality and specificity of genetic-environmental factors related to heterogeneity in proactive and reactive aggression’s development throughout childhood.MethodsParticipants were 223 monozygotic and 332 dizygotic pairs. Teacher reports of aggression were obtained at 6, 7, 9, 10 and 12 years of age. Joint development of both phenotypes were analyzed through a multivariate latent growth curve model. Set point, differentiation, and genetic maturation/environmental modulation hypotheses were tested using a biometric decomposition of intercepts and slopes.ResultsCommon genetic factors accounted for 64% of the total variation of proactive and reactive aggression’s intercepts. Two other sets of uncorrelated genetic factors accounted for reactive aggression’s intercept (17%) on the one hand, and for proactive (43%) and reactive (13%) aggression’s slopes on the other. Common shared environmental factors were associated with proactive aggression’s intercept (21%) and slope (26%) and uncorrelated shared environmental factors were also associated with reactive aggression’s slope (14%). Common nonshared environmental factors explained most of the remaining variability of proactive and reactive aggression slopes.ConclusionsA genetic differentiation hypothesis common to both phenotypes was supported by common genetic factors associated with the developmental heterogeneity of proactive and reactive aggression in childhood. A genetic maturation hypothesis common to both phenotypes, albeit stronger for proactive aggression, was supported by common genetic factors associated with proactive and reactive aggression slopes. A shared environment set point hypothesis for proactive aggression was supported by shared environmental factors associated with proactive aggression baseline and slope. Although there are many common features to proactive and reactive aggression, the current research underscores the advantages of differentiating them when studying aggression.

研究背景：鲜有研究基于发展框架对主动性攻击（proactive aggression）与反应性攻击（reactive aggression）展开探究。尽管已有研究指出二者具有独特的相关因素、预测因子与结局，但主动性攻击与反应性攻击之间仍存在显著相关。据我们所知，目前尚无实证研究考察两种攻击亚型的遗传与环境基础的共同性。本研究旨在探讨贯穿儿童期的主动性攻击与反应性攻击发展异质性相关的遗传-环境因素的共同性与特异性。

研究方法：本研究的被试为223对同卵双生子（monozygotic）与332对异卵双生子（dizygotic）。研究采用教师评定方式，在儿童6、7、9、10及12岁时收集其攻击行为的评定数据。通过多变量潜增长曲线模型（multivariate latent growth curve model）分析两种攻击表型（phenotype）的联合发展轨迹。采用截距与斜率的遗传计量学分解方法，检验设定点假说、分化假说以及遗传成熟/环境调节假说。

研究结果：共同遗传因素可解释主动性攻击与反应性攻击截距总变异的64%。另有两组互不相关的遗传因素，分别解释反应性攻击截距的17%，以及主动性攻击（43%）与反应性攻击（13%）斜率的变异。共同共享环境（shared environment）因素与主动性攻击的截距（21%）及斜率（26%）相关，互不相关的共享环境（shared environment）因素也与反应性攻击的斜率（14%）相关。共同非共享环境（nonshared environment）因素则解释了主动性攻击与反应性攻击斜率剩余变异中的绝大部分。

研究结论：与两种攻击表型（phenotype）共通的遗传分化假说，得到了与儿童期主动性攻击与反应性攻击发展异质性相关的共同遗传因素的支持。尽管针对主动性攻击的效应更强，但两种表型共通的遗传成熟假说，也得到了与主动性攻击与反应性攻击斜率相关的共同遗传因素的支持。主动性攻击的共享环境设定点假说，得到了与主动性攻击基线水平及斜率相关的共享环境因素的支持。尽管主动性攻击与反应性攻击存在诸多共同特征，但本研究凸显了在攻击行为研究中对二者进行区分的重要意义。