The Dopamine System: Insights between Kidney and Brain

Chronic kidney disease (CKD) is one of the most common diseases in adult age, and it is typical of older adults. Recent data suggest that almost half of the elders have CKD. It is now clear that CKD is accompanied, in the early stages, by cognitive impairment, together with depression and subtle abnormalities in motor control (such as gait and balance alterations).

Several data suggest a link between brain dopamine and kidney diseases. Metabolic syndrome and diabetes can affect dopamine neuron survival (leading to Parkinson's disease). Several uremic toxins in CKD (uric acid, indoxyl sulfate) and trace elements accumulating in CKD (aluminum, manganese) can also modify the dopaminergic system. Hormones produced by the kidney such as vitamin D are neuroprotective for dopamine neurons. Dopaminergic drugs are useful for the treatment of a common sleep disorder in CKD, the restless legs syndrome. However, experiments on animal models of CKD show conflicting results regarding a modification of dopamine neurons.

Several observations suggest a limited relevance of the dopaminergic system in CKD-related cognitive impairment. However, a common sleep disturbance in CKD, the restless legs syndrome, improves with dopaminergic drugs. Therefore, it remains to be established the role of the dopamine system in subtle motor dysfunction observed in CKD, such as tremors, gait alterations, and central sleep apnea.