Nonmotor Disorders and Their Correlation With Dopamine

Abstract

Many of the nonmotor symptoms in Parkinson disease have a dopaminergic basis, whether the result of dopaminergic degeneration or as a result of dopaminergic treatment. In the latter case, the symptoms may be genuine side effects of drugs (hypotension, pathologic gambling, etc.) or they may be secondary either to the pathoplastic effect they have on the natural course of the disease (nonmotor fluctuations) or to the lack of dopamine (apathy, depression, dopamine withdrawal syndrome, etc.). In all these cases, dopaminergic treatment can be helpful. However, many other nonmotor (and motor) symptoms will have no correlation with dopamine; therefore, they require different treatments, very often with little efficacy, as in apathy or cognitive decline.

Motor Fluctuations Development Is Associated with Non-Motor Symptoms Burden Progression in Parkinson’s Disease Patients: A 2-Year Follow-Up Study

“…To reduce NMS burden in PD patients has been demonstrated to be associated with an improvement in QoL [14,15]. In summary, our findings reinforce the idea that there is a close relationship between motor and NMS and that dopaminergic treatment can be helpful in some cases [5,10].…”

“…Increasing dopamine activity not only in the striatum but also in other areas of the brain could improve some NMS such as attention, executive functions, apathy, depression, anxiety, restless legs and periodic limb movements, urinary urgency, nocturia, dribbling of saliva, constipation, pain, or fatigue [5][6][7][8][9]. Moreover, NMS can be related to dopamine changes in brain and blood [10]. Thus, some patients can suffer from non-motor fluctuations (NMF) (i.e., NMS that fluctuate during the day) [11] or can experience motor fluctuations (MF) with the development of NMS during the OFF episodes (e.g., pain associated with dystonia) [12].…”

Many Faces of Parkinson’s Disease: Non-Motor Symptoms of Parkinson’s Disease

“…Bradykinesia and rigidity are most likely to get better with levodopa, while axial problems such as balance, speech and gait disturbance do not show adequate response to levodopa compared to bradykinesia and rigidity. In the same manner, NMS can be classified with the relationship of dopaminergic treatment ( Table 1 ) [ 20 , 21 ]. Recent positron emission tomography study suggests a dopaminergic contribution to some NMS [ 22 ] and such symptoms related to the dopamine replacement therapy (DRT).…”

Effect of a Traditional Chinese Herbal Medicine Formulation on Cell Survival and Apoptosis of MPP+-Treated MES 23.5 Dopaminergic Cells

“…Although the biochemical and molecular pathogenesis of the loss of dopaminergic neurons in PD has not yet been fully understood, it is believed that the pathogenesis is multifactorial which includes oxidative stress, mitochondrial dysfunction, and glutamate-mediated excitotoxicity and inflammation [3, 4]. Emerging evidence also shows that apoptotic pathways are probably involved in the death of dopaminergic neurons in PD [5, 6].…”