Despite years of research on pain comorbidity with affective disorders and cognitive deficits, it is still unclear how deficit in attention co-occurs with chronic pain. It is likely that altered neuroplasticity and or dysregulated neurotransmitters induced by chronic pain, at which pain and cognitive processing systems overlap, may have a negative effect on cognitive processing such as attention. One of the main common networks involved in attentional and pain processing is the noradrenergic system originating from the locus coeruleus (LC). We hypothesized that heightened noradrenaline release from LC induced by chronic pain could cause a deficit in visual attention. For this purpose, performance on the 5-choice serial reaction time test (5-CSRTT) was tested in animals with and without a chronic constriction injury and a selective depletion of noradrenaline in the LC. In addition, pain sensitivity was measured via mechanical allodynia and thermal hyperalgesia. We found that the increase in pain sensitivity following chronic pain correlates with a decline in executive functions as measured by 5-CSRTT. This was true in conditions of both low and high attentional demand. Interestingly, a selective depletion of noradrenaline in LC improved the attentional deficits caused by chronic pain. We argue that changes to the noradrenergic system originating in LC can improve deficits in visual attention induced by chronic pain. Deficit in attention is a common comorbidity among patients with chronic pain which adversely affects them in their family and work lives. Patients struggle with functional impairment due to pain, and deficite in attention adds to this dysfunction. Our findings identify the NE-LC system as a key mediator between chronic pain and the attentional deficits associated with this. This finding calls for further investigations concerning treatments related to the noradrenergic system to reduce the malicious effects of chronic pain.

中文翻译：

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蓝斑去甲肾上腺素能系统控制慢性疼痛引起的视觉注意力缺陷

尽管对疼痛与情感障碍和认知缺陷共存疾病进行了多年的研究，但仍不清楚注意力缺陷如何与慢性疼痛同时发生。慢性疼痛引起的神经可塑性改变和/或神经递质失调（其中疼痛和认知处理系统重叠）可能会对注意力等认知处理产生负面影响。参与注意力和疼痛处理的主要常见网络之一是源自蓝斑 (LC) 的去甲肾上腺素能系统。我们假设慢性疼痛引起的 LC 去甲肾上腺素释放增加可能导致视觉注意力缺陷。为此，在有或没有慢性压迫性损伤和 LC 中去甲肾上腺素选择性消耗的动物中测试了 5 选择系列反应时间测试 (5-CSRTT) 的性能。此外，通过机械异常性疼痛和热痛觉过敏来测量疼痛敏感性。我们发现，慢性疼痛后疼痛敏感性的增加与 5-CSRTT 测量的执行功能下降相关。在注意力需求低和高的情况下都是如此。有趣的是，LC 中去甲肾上腺素的选择性消耗改善了慢性疼痛引起的注意力缺陷。我们认为，源自 LC 的去甲肾上腺素能系统的变化可以改善慢性疼痛引起的视觉注意力缺陷。注意力缺陷是慢性疼痛患者常见的合并症，对他们的家庭和工作生活产生不利影响。患者因疼痛而遭受功能障碍的困扰，而注意力缺陷又加剧了这种功能障碍。我们的研究结果表明 NE-LC 系统是慢性疼痛和与之相关的注意力缺陷之间的关键调节因素。这一发现需要进一步研究与去甲肾上腺素能系统相关的治疗方法，以减少慢性疼痛的不良影响。