Gillespie Nathan A, Kendler Kenneth S, Prescott Carol A, Aggen Steven H, Gardner Charles O, Jacobson Kristen, Neale Michael C
Department of Psychiatry, Virginia Institute of Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA 23219-1534, USA.
Psychol Med. 2007 Jul;37(7):947-59. doi: 10.1017/S0033291707009920. Epub 2007 Apr 20.
Although an obvious environmental factor influencing drug use, the sources of individual differences in drug availability (DA) are unknown.
This report is based on 1788 adult males from the Mid-Atlantic Twin Registry who participated in a structured telephone interview that included retrospective assessments of DA (cigarette, alcohol, marijuana, cocaine and stimulants) between ages 8 and 25. We fitted a biometric dual change score (DCS) model, adapted for ordinal data, to model latent growth and estimate the genetic and environmental components of variance over time.
DA, despite being considered an environmental risk factor, is under both genetic and environmental control. For cigarette, alcohol, marijuana and cocaine availability, there was an overall increase in additive genetic variance and a decline in shared environmental variance over time. Non-shared environmental variance remained steady. Stimulant availability did not follow this pattern. Instead, there was an upswing in shared environmental effects with increasing age.
We have modeled the genetic and environmental architecture of changes in DA across adolescence. The rise in additive genetic variance over time coincides with acceleration in the expression of individual differences, probably brought on by an increase in personal freedom and a reduction in social constraints. Understanding the etiology of DA is likely to reveal key components, acting directly or indirectly, in the pathway(s) leading to drug initiation, abuse and dependence.
尽管药物可获得性（DA）是影响药物使用的一个明显环境因素，但其个体差异的来源尚不清楚。
本报告基于来自大西洋中部双胞胎登记处的1788名成年男性，他们参与了一次结构化电话访谈，其中包括对8至25岁期间DA（香烟、酒精、大麻、可卡因和兴奋剂）的回顾性评估。我们拟合了一个适用于有序数据的生物统计学双变化分数（DCS）模型，以模拟潜在生长并估计随时间变化的遗传和环境方差成分。
尽管DA被认为是一种环境风险因素，但它受遗传和环境的双重控制。对于香烟、酒精、大麻和可卡因的可获得性，随着时间的推移，加性遗传方差总体增加，共享环境方差下降。非共享环境方差保持稳定。兴奋剂的可获得性没有遵循这种模式。相反，随着年龄的增长，共享环境效应呈上升趋势。
我们对青少年期DA变化的遗传和环境结构进行了建模。随着时间的推移，加性遗传方差的增加与个体差异表达的加速相吻合，这可能是由个人自由增加和社会约束减少所导致的。了解DA的病因可能会揭示在导致药物起始、滥用和依赖的途径中直接或间接起作用的关键成分。
