α-synuclein protein levels are increased in alcoholic patients and are linked to craving

Background: Alpha synuclein has been found to be increased in dopamine neurones of cocaine abusers and in rats whose alcohol preference is inbred. Furthermore, increased alpha-synuclein messenger RNA expression has been linked to craving in patients with alcoholism. The aim of the current study was to investigate whether protein levels of a synuclein in alcoholics are changed and possibly influence alcohol craving. Methods: The alpha-synuclein protein expression level was measured by enzyme-linked immunosorbent assay in the serum of 49 male alcoholics and 50 nondrinking healthy controls. Alcohol craving was assessed by the Obsessive-Compulsive Drinking Scale total score, including subscales for obsessive and compulsive craving. Results: alpha-Synuclein protein expression in patients with alcoholism (14.33 ng/ml; SD, 13.01 ng/ml) was significantly higher (t test, T = 3.66,p < 0.0001) when compared with that of healthy controls (5.92 ng/ml; SD, 9.72 ng/ml). Using a multivariate analysis, all craving scores (Obsessive-Compulsive Drinking Scale total score and obsessive and compulsive subscale scores) in alcoholics were significantly associated with their alpha-synuclein protein levels (multiple linear regression, p < 0.014). Conclusions: To our knowledge, this is the first study evaluating a-synuclein protein expression in alcoholics. The current study provides further evidence of altered alpha-synuclein levels in patients with alcoholism and their linkage to alcohol craving. Because a synuclein is involved in the modulation of dopaminergic neurotransmission, these results deliver further pathophysiological explanations of craving mechanisms.