Adaptive and non-adaptive models of depression: A comparison using register data on antidepressant medication during divorce

Divorce is associated with an increased probability of a depressive episode, but the causation of events remains unclear. Adaptive models of depression propose that depression is a social strategy in part, whereas non-adaptive models tend to propose a diathesis-stress mechanism. We compare an adaptive evolutionary model of depression to three alternative non-adaptive models with respect to their ability to explain the temporal pattern of depression around the time of divorce. Register-based data (304,112 individuals drawn from a random sample of 11% of Finnish people) on antidepressant purchases is used as a proxy for depression. This proxy affords an unprecedented temporal resolution (a 3-monthly prevalence estimates over 10 years) without any bias from non-compliance, and it can be linked with underlying episodes via a statistical model. The evolutionary-adaptation model (all time periods with risk of divorce are depressogenic) was the best quantitative description of the data. The non-adaptive stress-relief model (period before divorce is depressogenic and period afterwards is not) provided the second best quantitative description of the data. The peak-stress model (periods before and after divorce can be depressogenic) fit the data less well, and the stress-induction model (period following divorce is depressogenic and the preceding period is not) did not fit the data at all. The evolutionary model was the most detailed mechanistic description of the divorce-depression link among the models, and the best fit in terms of predicted curvature; thus, it offers most rigorous hypotheses for further study. The stress-relief model also fit very well and was the best model in a sensitivity analysis, encouraging development of more mechanistic models for that hypothesis.离婚与抑郁发作的风险升高存在显著相关性，但二者的因果关联机制仍未明确。抑郁的适应性模型认为，抑郁在一定程度上属于一种社会适应策略；而非适应性模型则多提出素质-应激（diathesis-stress）机制作为解释框架。本研究针对1种抑郁适应性进化模型与3种备选非适应性模型，对比其解释离婚前后抑郁发作时间分布模式的能力。本研究采用基于芬兰全国登记系统的数据集：该数据集从芬兰11%人口的随机抽样中选取304112名个体，以抗抑郁药物购药记录作为抑郁的替代指标（proxy）。该替代指标具备前所未有的时间分辨率——可提供长达10年的每3个月一次的抑郁患病率估算值，且不受服药不依从性带来的信息偏倚影响，同时可通过统计模型与潜在的抑郁发作事件建立关联。进化适应性模型（即所有存在离婚风险的时期均具有致抑郁效应）对观测数据的定量拟合效果最优。非适应性应激缓解模型（即离婚前阶段具有致抑郁效应，离婚后阶段则无此效应）对数据的定量拟合效果位列第二。峰值应激模型（即离婚前后的阶段均可能具有致抑郁效应）对数据的拟合效果一般；而应激诱导模型（即仅离婚后阶段具有致抑郁效应，此前阶段无此效应）则完全无法拟合观测数据。在所有对比模型中，进化适应性模型对离婚与抑郁之间关联的机制阐释最为详尽，且在预测曲线拟合度方面表现最优，因此可为后续研究提供最为严谨的研究假设。应激缓解模型的拟合效果同样优异，且在敏感性分析中被评为最优模型，这为针对该假说开发更具机制性的研究模型提供了实证支撑。