Increase of α-Synuclein in the Peripheral Blood of Subjects with Methamphetamine Use Disorder.

OBJECTIVE: Methamphetamine (MA) use has created significant public health problems worldwide. Its chronic abuse causes neurotoxicity resulting in disruption of neural plasticity and early onset of neurodegenerative diseases. Therefore, there is need for a biomarker to evaluate the neurotoxicity caused by MA. This study investigates the expression levels of α-synuclein (α-Syn), brain-derived neurotrophic factor (BDNF), and neuron-specific enolase (NSE) in the blood of patients with MA use disorder to identify potential biomarkers. METHODS: We collected blood samples from 60 subjects (30 normal healthy controls and 30 patients with MA use disorder [MA group]). We used multiplex assay kits to analyze the expression levels of α-Syn, BDNF, and NSE in the blood of these subjects. RESULTS: Beck Depression Inventory and Beck Anxiety Inventory scale scores were significantly different between the control and MA groups. The expression level of α-Syn in the MA group was significantly increased compared to that in the control group (z value=-1.986, p=0.0473). In contrast, BDNF in the MA group tended to increase as the duration of MA use increased (r=0.323, p=0.082). CONCLUSION: We identified an increase of α-Syn in the blood of the MA group. This finding suggests that the α-Syn level increases in the brain after exposure to MA by passing through the blood brain barrier. This result provides useful information for potential biomarkers in diagnosis of neurodegenerative diseases caused by MA abuse.