Abstract
BackgoundThe purpose of this study was to assess the biological and clinical effects of n-acetyl-cysteine (NAC) in Parkinson’s disease (PD).MethodsThe overarching goal of this pilot study was to generate additional data about potentially protective properties of NAC in PD, using an in vitro and in vivo approach. In preparation for the clinical study we performed a cell tissue culture study with human embryonic stem cell (hESC)-derived midbrain dopamine (mDA) neurons that were treated with rotenone as a model for PD. The primary outcome in the cell tissue cultures was the number of cells that survived the insult with the neurotoxin rotenone. In the clinical study, patients continued their standard of care and were randomized to receive either daily NAC or were a waitlist control. Patients were evaluated before and after 3 months of receiving the NAC with DaTscan to measure dopamine transporter (DAT) binding and the Unified Parkinson’s Disease Rating Scale (UPDRS) to measure clinical symptoms.ResultsThe cell line study showed that NAC exposure resulted in significantly more mDA neurons surviving after exposure to rotenone compared to no NAC, consistent with the protective effects of NAC previously observed. The clinical study showed significantly increased DAT binding in the caudate and putamen (mean increase ranging from 4.4% to 7.8%; p<0.05 for all values) in the PD group treated with NAC, and no measurable changes in the control group. UPDRS scores were also significantly improved in the NAC group (mean improvement of 12.9%, p = 0.01).ConclusionsThe results of this preliminary study demonstrate for the first time a potential direct effect of NAC on the dopamine system in PD patients, and this observation may be associated with positive clinical effects. A large-scale clinical trial to test the therapeutic efficacy of NAC in this population and to better elucidate the mechanism of action is warranted.Trial RegistrationClinicalTrials.gov NCT02445651
Highlights
Parkinson’s disease (PD) is a devastating neurodegenerative disorder involving the dopamine system that affects more than a million Americans [1]
The cell line study showed that NAC exposure resulted in significantly more midbrain dopamine (mDA) neurons surviving after exposure to rotenone compared to no NAC, consistent with the protective effects of NAC previously observed
The clinical study showed significantly increased dopamine transporter (DAT) binding in the caudate and putamen in the PD group treated with NAC, and no measurable changes in the control group
Summary
Parkinson’s disease (PD) is a devastating neurodegenerative disorder involving the dopamine system that affects more than a million Americans [1]. To date no medication has been shown to slow progression in PD. Some supportive therapies such as exercise have shown improved quality of life [2,3], but there is a significant need to continue exploring therapies that might improve symptoms and positively impact the disease process. PD patients often seek adjunct therapies such as dietary supplements, even though most have little to no supportive data [4,5]. Testing those products that have at least a theoretical rationale congruous with what is known of the pathophysiology of PD could have value for patients and providers
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