Taylor Mark J, Martin Joanna, Butwicka Agnieszka, Lichtenstein Paul, D'Onofrio Brian, Lundström Sebastian, Larsson Henrik, Rosenqvist Mina A
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, UK.
J Child Psychol Psychiatry. 2023 Nov;64(11):1608-1616. doi: 10.1111/jcpp.13854. Epub 2023 Jul 6.
Attention-deficit/hyperactivity disorder (ADHD) is an increasingly commonly diagnosed neurodevelopmental condition. One possibility is that this reflects a genuine increase in the prevalence of ADHD due to secular environmental changes, yet this hypothesis remains untested. We therefore investigated whether the genetic and environmental variance underlying ADHD, and traits of ADHD, has changed over time.
We identified twins born from 1982 to 2008 from the Swedish Twin Registry (STR). We linked the STR with the Swedish National Patient Register and Prescribed Drug Register to identify diagnoses of ADHD and prescriptions of ADHD medication for these twins. We also utilized data collected from participants in the Child and Adolescent Twin Study in Sweden (CATSS), born from 1992 to 2008. Their parents completed a structured ADHD screening tool, which was used to measure traits of ADHD and assign broad screening diagnoses of ADHD. We used the classical twin design to test whether the degree to which variation in these measures was influenced by genetic and environmental variation changed over time.
We included 22,678 twin pairs from the STR and 15,036 pairs from CATSS. The heritability of ADHD in the STR ranged from 66% to 86% over time, although these fluctuations were not statistically significant. We observed a modest increase in variance in ADHD traits, from 0.98 to 1.09. This was driven by small increases in the underlying genetic and environmental variance, with heritability estimated as 64%-65%. No statistically significant changes in variance in screening diagnoses were observed.
The relative contribution of genetic and environmental factors to ADHD has remained stable over time, despite its increasing prevalence. Thus, changes in the underlying etiology of ADHD over time are unlikely to explain the increase in ADHD diagnoses.
注意力缺陷多动障碍（ADHD）是一种诊断日益普遍的神经发育疾病。一种可能性是，这反映了由于长期环境变化导致ADHD患病率的真正上升，但这一假设仍未得到验证。因此，我们调查了ADHD潜在的遗传和环境变异以及ADHD特征是否随时间发生了变化。
我们从瑞典双胞胎登记处（STR）中识别出1982年至2008年出生的双胞胎。我们将STR与瑞典国家患者登记处和处方药登记处相联系，以确定这些双胞胎的ADHD诊断和ADHD药物处方。我们还利用了从瑞典儿童和青少年双胞胎研究（CATSS）的参与者那里收集的数据，这些参与者出生于1992年至2008年。他们的父母完成了一个结构化的ADHD筛查工具，该工具用于测量ADHD特征并进行ADHD的广泛筛查诊断。我们使用经典双胞胎设计来测试这些测量指标的变异受遗传和环境变异影响的程度是否随时间发生了变化。
我们纳入了来自STR的22678对双胞胎和来自CATSS的15036对双胞胎。随着时间的推移，STR中ADHD的遗传度在66%至86%之间，尽管这些波动没有统计学意义。我们观察到ADHD特征的变异有适度增加，从0.98增加到1.09。这是由潜在的遗传和环境变异的小幅增加驱动的，遗传度估计为64%-65%。在筛查诊断的变异中未观察到统计学上的显著变化。
尽管ADHD患病率不断上升，但遗传和环境因素对ADHD的相对贡献随时间保持稳定。因此，ADHD潜在病因随时间的变化不太可能解释ADHD诊断的增加。
