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 alpha 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 alpha-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 alpha synuclein is involved in the modulation of dopaminergic neurotransmission, these results deliver further pathophysiological explanations of craving mechanisms.