For the ERP protocol, subjects with hepatic encephalopathy/cirrhosis of the liver, multiple sclerosis, stroke, seizures, head injury, any other history of neurological, psychiatric disorders and neurosurgical procedures were excluded. Subjects who were taking medication that affects/influences brain functioning, who tested positive for HIV, had uncorrected vision and/or hearing deficits, or had used any psychoactive substances in the past 5 days were also excluded. Prior to neurophysiological assessment, breath analyzers were used to exclude subjects who tested positive for the presence of alcohol.
