Disturbances of dopamine (DA), serotonin (5-HT) and/or norepinephrine (NE) functions are implied in attention-deficit hyperactivity disorder (ADHD). However, the precise cortical and subcortical mechanisms are still not fully understood. In the present survey, we conducted a PUBMED search, which provided 37 in vivo investigations with PET and SPECT on 419 ADHD patients and 490 controls. The retrospective analysis revealed increased striatal DA transporter (DAT) in adolescent as well as adult medication-naïve and not acutely medicated patients. In acutely medicated adults, DAT was not different from controls. Midbrain DAT was normal in adults, but decreased in adolescents. Striatal D2 receptor (R) binding was normal in both adolescents (not acutely medicated) and adults (acutely medicated and not acutely medicated). In medication-naïve adults, DA synthesis was decreased in putamen and amygdala, but normal in the whole striatum and midbrain. In not acutely medicated adults, DA synthesis was reduced in putamen, whole striatum, prefrontal cortex, frontal cortex, amygdala and midbrain, whereas, in adolescents, no regional differences were observed. In adult (not acutely medicated) subjects, cingulate D1R was reduced. 5-HT transporter (SERT) binding was decreased in striatum and thalamus, but normal in midbrain, neocortex and limbic regions, whereas, in medication-naïve adults, SERT was diminished in striatum and midbrain, but normal in thalamus and neocortex. The findings suggest transient stages of synaptic DA shortage as well as DA surplus in individual brain regions, which elicit presynaptic as well as postsynaptic compensatory mechanisms, striving to attain functional homeostasis. Thereby, it remains a matter of debate, whether ADHD may be characterized by a general hypo- or hyperactivity of DA and/or 5-HT function.

中文翻译：

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青少年和成人注意力缺陷多动障碍的单胺能功能减退或功能亢进？

注意缺陷多动障碍 (ADHD) 中暗示了多巴胺 (DA)、血清素 (5-HT) 和/或去甲肾上腺素 (NE) 功能的紊乱。然而，精确的皮层和皮层下机制仍未完全了解。在本次调查中，我们进行了 PUBMED 搜索，提供了 37体内对 419 名 ADHD 患者和 490 名对照者进行 PET 和 SPECT 调查。回顾性分析显示，青少年以及成人未用药和未急性用药患者的纹状体 DA 转运蛋白 (DAT) 增加。在急性用药的成年人中，DAT 与对照组没有什么不同。成人中脑 DAT 正常，但在青少年中下降。纹状体D2受体 (R) 结合在青少年（非急性用药）和成人（急性用药和非急性用药）中均正常。在未接受药物治疗的成年人中，壳核和杏仁核中的 DA 合成减少，但在整个纹状体和中脑中正常。在未急性用药的成年人中，壳核、整个纹状体、前额叶皮层、额叶皮层、杏仁核和中脑的 DA 合成减少，而在青少年中，没有观察到区域差异。在成人（非急性用药）受试者中，扣带回 D1R 降低。5-HT 转运蛋白 (SERT) 结合在纹状体和丘脑中减少，但在中脑、新皮质和边缘区域正常，而在未接受药物治疗的成年人中，SERT 在纹状体和中脑中减少，但在丘脑和新皮质中正常。研究结果表明，单个大脑区域存在突触 DA 短缺和 DA 过剩的短暂阶段，这引发了突触前和突触后补偿机制，努力实现功能性稳态。因此，ADHD 是否可能以 DA 和/或 5-HT 功能的普遍低或过度活跃为特征仍然是一个争论的问题。