Larger MMN amplitudes have been reported in recently detoxified alcoholics (Kathmann et al., 1995). The automatic stimulus change detector mechanism associated with MMN generation is impaired in chronic alcoholics over the age of 40, suggesting that the neurotoxic effects of chronic consumption of alcohol are more prone to appear after a critical age (Polo et al., 1999). One study showed no MMN differences between controls and alcoholics who were abstinent for an average of 6 years (Fein et al., 2004), while another (Pekkonen et al., 1998) observed that increasing durations of abstinence reduced the MMN amplitude, perhaps indicating improved efficiency of covert processes upon abstinence. Ahveninen et al. (2000) found significantly enhanced MMN amplitudes to deviant sounds that correlated with reaction time lag caused by deviants, indicating pronounced distractibility and impaired reorienting to the relevant task in alcoholics. The MMN enhancement predicted poorer hit rates in alcoholics and along with reaction time lag it also correlated with an early onset of AUDs. Impairment in neural inhibition of involuntary attention shifting may be more pronounced in early-onset alcoholics. Grau and colleagues
