Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children worldwide, and also the recognition of its persistence into adulthood is increasing. While ADHD in childhood is highly heritable and mostly driven by familial factors, during adulthood it appears to show a lower heritability, even if there is not total agreement on this yet. This disorder often co-occurs with many other conditions, which also vary across the different stages of development, and several studies have used the twin design to investigate these comorbidities, giving valuable insights into the origins of the observed co-occurrence. This review aims to summarize the main results of twin research, according to the following domains: individual traits, cognitive impairment, behavioral manifestations, clinical conditions and psychosocial risk factors. Individual features seem to play a role in this symptomatology and include personality traits such as negative emotionality, personality disorders and temperamental dimensions with a predominance of novelty seeking. At a lower level, ADHD is associated with both functional and anatomic brain characteristics. ADHD is also associated with some forms of cognitive impairment, such as sluggish cognitive tempo, and learning disabilities, with a specific predisposition to reading disability. In addition, ADHD is strongly associated with externalizing disorders such as conduct disorder and oppositional defiant disorder, and some behavioral outcomes, particularly substance use and abuse both in adolescence and adulthood. Moreover, ADHD symptoms often overlap with other psychological disorders, namely affective and internalizing disorders, as well as autism spectrum disorder and autistic-like traits in a wider sense. Notably, a genetic overlap has been found between asthma and ADHD, particularly with respect to hyperactivity/impulsivity dimensions. ADHD also appears to represent a risk factor for disordered eating, and, more specifically, for binge eating and bulimia nervosa. Finally, among psychosocial factors, an association has been proposed between childhood maltreatment and ADHD symptoms.

中文翻译：

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多动症及其合并症的性质，特征：双胞胎研究的叙事综述。

注意缺陷/多动障碍（ADHD）是全世界儿童中常见的神经发育障碍，并且对其持续性至成年期的认识也在增加。尽管儿童多动症的遗传力很高，并且主要受家族因素的影响，但成年期遗传力似乎较低，即使对此尚未达成完全共识。这种疾病通常与许多其他疾病同时发生，并且在不同的发育阶段也有所不同，一些研究已经使用双胞胎设计研究了这些合并症，从而为观察到的同时发生的起源提供了宝贵的见解。这篇综述旨在根据以下领域总结双生子研究的主要结果：个人特征，认知障碍，行为表现，临床情况和社会心理危险因素。个体特征似乎在这种症状中起作用，并且包括个性特征，例如负面情绪，人格障碍和性情维度，以寻求新颖性为主。在较低的水平上，ADHD与功能性和解剖性脑部特征相关。ADHD还与某些形式的认知障碍有关，例如迟钝的认知节奏和学习障碍，特别容易导致阅读障碍。另外，ADHD还与外在性疾病如行为障碍和对立反抗性障碍以及一些行为结果密切相关，特别是在青少年和成年期使用和滥用药物。此外，多动症的症状通常会与其他心理疾病重叠，即情感和内在性障碍，以及自闭症谱系障碍和更广泛意义上的自闭症样特征。值得注意的是，已经发现哮喘和ADHD之间存在遗传重叠，特别是在过度活跃/冲动方面。多动症也似乎是饮食失调的危险因素，更具体地说，是暴饮暴食和神经性贪食症的危险因素。最后，在社会心理因素中，有人提出了儿童期虐待与多动症症状之间的联系。用于暴饮暴食和贪食症。最后，在社会心理因素中，有人提出了儿童期虐待与多动症症状之间的联系。用于暴食和神经性贪食症。最后，在社会心理因素中，有人提出了儿童期虐待与多动症症状之间的联系。