The central finding of this study, with regard to its primary goal, is of a marginally significant reduction of P3b amplitude in 20–50 year old TNAD compared to age and gender comparable NAC. The magnitude of the P3b reduction was much smaller than we previously observed in treated long-term abstinent alcoholics (LTAA) (averaging 6.7 years abstinence and just over 46 years of age) compared to their age and gender comparable NAC (Fein and Chang, 2006). The effect size in the study of treated LTAA was about five-times that observed in the current study. This dramatic difference in effect size was the result of two factors: there was both a greater variability of P3b amplitude in younger vs. older cohorts and a smaller mean difference in P3b amplitude between TNAD and NAC vs. LTAA and their age appropriate NAC.
