A developmental behavior-genetic perspective on alcoholism risk

Abstract

Although behavioral problems associated with abuse of alcohol emerge during late adolescence and adulthood, some behavioral characteristics indicative of an increased risk of alcoholism may already be obvious during early childhood. Studies in several countries have demonstrated that children with high levels of novelty-seeking behavior and low levels of harm-avoidance behavior are more likely to develop alcohol-related problems during adolescence. Moreover, as early as age 3, children at high risk of future alcoholism because of a family history are more active, more impatient, and more aggressive than matched controls of low-risk children. Causal influences on the initiation of drinking must be distinguished from those that affect patterns of consumption once drinking is initiated. Studies of adolescent twins have demonstrated that initiation of drinking is primarily influenced by the drinking status of parents, siblings, and friends and by socioregional differences in the environments within which adolescent twins reside. The influence of genetic factors is negligible. Conversely, once initiated, differences in frequency and quantity of drinking are strongly influenced by genetic factors. However, these influences, too, are modulated by sibling and peer effects and by regional environmental variation.

Figure 1

Correlation for alcohol involvement among biologically unrelated (i.e., adoptive) siblings. Alcohol involvement was defined as a composite measure of the frequency of drinking, frequency of problem drinking, and affiliation with drinking peers. Adoptive siblings who were more similar in their demographic characteristics (i.e., had the same gender or were similar in age) showed greater correlation for alcohol involvement than did siblings who were more disparate (i.e., had different genders or were far apart in age). SOURCE: McGue et al. 1996.

Figure 2

Correlation with respect to abstinence among 16-year-old identical (i.e., monozygotic [MZ]) and fraternal (i.e., dizygotic [DZ]) Finnish twin brothers living in the greater Helsinki area or in rural areas in northern Finland. In the Helsinki area, where abstinence rates among 16-year-olds are about half as high as in northern Finland, the twins’ zygosity strongly influenced the degree of correlation for abstinence. In northern Finland, no difference between MZ and DZ twin brothers existed. SSDZ = same-sex dizygotic. SOURCE: Rose et al. 1998.

Figure 1

Correlation in drinking behaviors (i.e., abstinence versus alcohol use and drinking or not to intoxication) among 16-year-old Finnish same-sex identical (i.e., monozygotic [MZ]) and fraternal (i.e., dizygotic [DZ]) twins. All pairs included in the study were asked whether they had ever used alcohol. Pairs in which both twins had previously used alcohol were asked whether they had ever drunk to intoxication. The correlation coefficient rho (ρ) measures the degree of association between the drinking behavior of the two twins. A ρ value of 1.0 indicates a perfect association between the twins’ self-reported drinking behavior. No significant difference existed in the correlation among MZ twins and the correlation among DZ twins.

Figure 2

Correlation in the frequency of lifetime or past-month alcohol use among 16-year-old Finnish same-sex identical (i.e., monozygotic [MZ]) and fraternal (i.e., dizygotic [DZ]) twin pairs in which both twins reported some alcohol use. The correlation coefficient rho (ρ) is a measure of the degree of association between the twins’ reported frequency of alcohol use. A ρ value of 1.0 indicates a perfect association in reported frequency of associated use by the two twins in each pair. The correlation was greater among MZ twins than among DZ twins. SOURCE: Rose et al. in press.

Figure 3

Proportion of Finnish twin pairs at age 16 who reported spending most of their leisure time with one another. Twins who spend more of their leisure time together also are more likely to develop similar drinking behaviors. FMZ = female monozygotic twins; MMZ = male monozygotic twins; FDZ = female dizygotic twins; MDZ = male dizygotic twins; OSDZ = opposite-sex dizygotic twins.

Figure 4

Socioregional differences in the correlation of alcohol consumption frequency in Finnish twins at age 18.5. Regardless of gender and zygosity, twin pairs living in rural areas showed greater correlation in drinking frequency than did twin pairs living in urban areas. MMZ = male monozygotic twins; MDZ = male dizygotic twins; FMZ = female monozygotic twins; FDZ = female dizygotic twins. SOURCE: Rose et al. 1997b.