Abstract
BACKGROUND: Although personality factors and family history of substance abuse influence how individuals experience pain and respond to analgesics, the combined effects of those factors have not been extensively studied. The objective of this study was to consider the possible role of personality trait of neuroticism and family history of alcoholism on the experience of pain and their role in the analgesic response to an ethanol challenge. METHODS: Forty-eight healthy subjects participated in this study; thirty-one had a positive family history of alcoholism (FHP), seventeen had a negative family history of alcoholism (FHN). They were also categorized based on their neuroticism (N) scores (low N = 28, and high N = 20). This was a double-blind, placebo-controlled, randomized, within-subject design study of intravenous administration of three doses of ethanol. The testing consisted of 3 separate test days scheduled at least 3 days apart. Test days included a placebo day (saline solution), low-exposure ethanol day (targeted breathalyzer = 0.040 g/dl), and high-exposure ethanol day (targeted breathalyzer = 0.100 g/dl). Noxious electrical stimulation and pain assessments were performed prior to start of infusion and at the 60-minute infusion mark. RESULTS: The analgesic effect of ethanol was mediated by an interaction between the personality trait of neuroticism and family history. Individuals with family history of alcoholism and high N scores reported significantly more analgesia on low dose of ethanol than those with low N scores. There was no difference in the analgesic response to ethanol among FHNs with low and high N scores. CONCLUSION: These findings support the conclusion that neuroticism and family history of alcoholism both influence the analgesic response of alcohol. Individuals with high N scores and FHP have the strongest response to ethanol analgesia particularly on the low exposure to alcohol.