Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University, Richmond, VA 23298-0126, USA.
J Affect Disord. 2012 Dec 15;142(1-3):90-7. doi: 10.1016/j.jad.2012.03.048. Epub 2012 Aug 16.
The nature of the relationship between major depression (MD) and phenotypes related to smoking behavior, including nicotine dependence (ND), is complicated. We present results from analyses comparing models wherein MD and ND are influenced by a shared latent factor to one in which causal pathways between phenotypes are examined.
Data were collected for 2906 adult male twins from a population-based sample. Structural equation modeling was used to derive path estimates for shared liability and causal models. MD was assessed according to DSM-III-R diagnostic criteria; ND was assessed using the Fagerstrom Test for Nicotine Dependence (FTND).
The best fitting shared liability model included genetic, but not environmental, influences shared between MD and FTND; a small proportion of these shared influences were also common to smoking initiation. The best fitting causal model included a unidirectional causal path from FTND to MD, with no direct genetic correlation between MD and smoking initiation. Model fit statistics indicated that these models provided nearly identical fits to the data, with the causal model providing a slightly superior AIC value.
The phenotypic association between MD and FTND is likely due to both a causal relationship, wherein increasing levels of nicotine dependence increase one's risk for depression, and to a shared genetic liability between the two.
This sample consists of Caucasian males born in Virginia, and findings might not be generalizable to others. Statistical power was less than ideal.
重度抑郁症（MD）与吸烟行为相关表型之间的关系较为复杂，包括尼古丁依赖（ND）。我们呈现了分析结果，这些结果比较了 MD 和 ND 受到共同潜在因素影响的模型与分析表型之间因果关系的模型。
从一个基于人群的样本中收集了 2906 名成年男性双胞胎的数据。使用结构方程模型得出共同易感性和因果模型的路径估计。根据 DSM-III-R 诊断标准评估 MD；使用尼古丁依赖 Fagerstrom 测试（FTND）评估 ND。
最佳拟合的共同易感性模型包括 MD 和 FTND 之间具有遗传影响但无环境影响的共同因素；这些共同因素的一小部分也与吸烟起始有关。最佳拟合的因果模型包括从 FTND 到 MD 的单向因果路径，MD 和吸烟起始之间没有直接的遗传相关性。模型拟合统计数据表明，这些模型几乎可以为数据提供相同的拟合，因果模型提供了略微优越的 AIC 值。
MD 和 FTND 之间的表型关联可能是由于因果关系，即尼古丁依赖程度的增加会增加一个人患抑郁症的风险，以及两者之间存在共同的遗传易感性。
该样本由弗吉尼亚州出生的白种男性组成，研究结果可能不适用于其他人。统计效能不太理想。
