| I. Heritability and DUI convictions: A twin study of driving under the influence. The U.S National Highway Traffic Safety Administration estimates that in 2002 there were 6.3 million traffic crashes and about 43,000 fatalities. Forty-one percent of all fatalities recorded that year, were alcohol-related. Nearly 1.5 million Driving While Intoxicated (DUI) arrests are made each year in the US. The enormous negative impact of drunk driving makes the study of the causal factors that underlie its expression a critical priority. The study was undertaken to assess the relative contributions of genetic and environmental influences on drunk-driving. General sex-limitation structural equation models were used to: (1) estimate the magnitude of genetic and environmental effects on male and female phenotypes, and (2) determine whether the same set of genes or shared environmental experiences influence drunk-driving in males and females. There were significant gender and age effects. Our findings, suggest that different set of genes may be influencing DUIs in males and females.;II. Genetic and environmental influences on excessive speeding. High speed drivers have been shown to be a high-risk group. Compared with non-speeders drivers in fatal crashes who have been speeding are more likely to: (1) have high blood alcohol concentrations, (2) have invalid licenses, and (3) not use seat belts. Males had an odds ratio of 1.86 (1.59-2.17). Relative to persons ages 50 and above, twins in the age range 20-49 years had greater than 8 times the risk for excessive speeding. For teenagers there was 3-fold increase in risk above that for persons ages 50 and above. Compared with females, males were twice more likely to engage in excessive speeding. In both males and females ages 20-49, only a small proportion (30%) of the variance in excessive speeding was due to genetic factors. The remaining 70% was due to individual specific environmental influences. Our findings suggest that the same set of genes may be influencing excessive speeding in males and females. A greater amount of the variance in excessive speeding is under individual specific environmental influence.;III. Personality and childhood behavioral factors as predictors of excessive speeding. The present study was undertaken to assess personality and childhood behavioral factors that predict excessive speeding convictions. Compared with females males were 1.8 times more likely to be driving at 80+ mph or 20+ mph above speed limit. Preferring to be center of attention or being content to remain on edge of things (i.e., sensation-seeking) (RR =1.94), and playing hooky from school (i.e., truancy) or cutting classes (RR=1.94) were the only variables that predicted excessive speeding conviction. Tendency for future high-risk behavior is manifested through childhood conduct disorder. (Abstract shortened by UMI.)... |
