McGill Group for Suicide Studies, Douglas Mental Health Research Institute, Department of Psychiatry, McGill University, Montreal, Canada; and Bordeaux Population Health Research Centre, Inserm U1219, University of Bordeaux, France.
Division of Psychology and Language Sciences, Department of Clinical, Educational and Health Psychology, University College London; and Social Genetic and Developmental Psychiatry Centre, King's College London, UK.
Br J Psychiatry. 2021 Sep;219(3):507-514. doi: 10.1192/bjp.2021.15.
Low birth weight is associated with adult mental health, cognitive and socioeconomic problems. However, the causal nature of these associations remains difficult to establish owing to confounding.
To estimate the contribution of birth weight to adult mental health, cognitive and socioeconomic outcomes using two-sample Mendelian randomisation, an instrumental variable approach strengthening causal inference.
We used 48 independent single-nucleotide polymorphisms as genetic instruments for birth weight (genome-wide association studies' total sample: n = 264 498) and considered mental health (attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, post-traumatic stress disorder (PTSD), schizophrenia, suicide attempt), cognitive (intelligence) and socioeconomic (educational attainment, income, social deprivation) outcomes.
We found evidence for a contribution of birth weight to ADHD (OR for 1 s.d. unit decrease (~464 g) in birth weight, 1.29; 95% CI 1.03-1.62), PTSD (OR = 1.69; 95% CI 1.06-2.71) and suicide attempt (OR = 1.39; 95% CI 1.05-1.84), as well as for intelligence (β = -0.07; 95% CI -0.13 to -0.02) and socioeconomic outcomes, i.e. educational attainment (β = -0.05; 95% CI -0.09 to -0.01), income (β = -0.08; 95% CI -0.15 to -0.02) and social deprivation (β = 0.08; 95% CI 0.03-0.13). However, no evidence was found for a contribution of birth weight to the other examined mental health outcomes. Results were consistent across a wide range of sensitivity analyses.
These findings support the hypothesis that birth weight could be an important element on the causal pathway to mental health, cognitive and socioeconomic outcomes.
低出生体重与成人心理健康、认知和社会经济问题有关。然而，由于混杂因素的存在，这些关联的因果性质仍然难以确定。
使用两样本 Mendelian 随机化（一种增强因果推断的工具变量方法）来估计出生体重对成人心理健康、认知和社会经济结果的贡献。
我们使用 48 个独立的单核苷酸多态性作为出生体重的遗传工具（全基因组关联研究的总样本：n=264498），并考虑了心理健康（注意力缺陷多动障碍（ADHD）、自闭症谱系障碍、双相情感障碍、重度抑郁症、强迫症、创伤后应激障碍（PTSD）、精神分裂症、自杀未遂）、认知（智力）和社会经济（教育程度、收入、社会剥夺）结果。
我们发现出生体重与 ADHD（每降低 1 个标准差（约 464 克）出生体重的比值比，1.29；95%置信区间 1.03-1.62）、PTSD（比值比=1.69；95%置信区间 1.06-2.71）和自杀未遂（比值比=1.39；95%置信区间 1.05-1.84）以及智力（β=-0.07；95%置信区间-0.13 至-0.02）和社会经济结果，即教育程度（β=-0.05；95%置信区间-0.09 至-0.01）、收入（β=-0.08；95%置信区间-0.15 至-0.02）和社会剥夺（β=0.08；95%置信区间 0.03-0.13）有关。然而，没有证据表明出生体重对其他检查的心理健康结果有贡献。结果在广泛的敏感性分析中是一致的。
这些发现支持了出生体重可能是心理健康、认知和社会经济结果的因果途径中的一个重要因素的假设。
