Karen Norberg

Binge Drinking Among Youths and Young Adults in the United States: 1979-2006

OBJECTIVE To evaluate trends in the past 30-day prevalence of binge drinking by age, sex, and student status, among youths and young adults in the United States between 1979 and 2006, a period that encompasses the federally mandated transition to a uniform legal drinking age of 21 years, and other policy changes aimed at curbing underage drinking. METHOD Data were analyzed from 20 administrations of the National Survey on Drug Use and Health, yielding a pooled sample of more than 500,000 subjects. Trends in relative risk for four different age groups, stratified by sex, relative to the 24- to 34-year-old reference group were calculated. We also examined trends in risk for binge drinking associated with student status (among college-age students) and race/ethnicity. RESULTS Significant reductions in relative risk for binge drinking over time were observed for 12- to 20-year-old males, but no changes were observed for females in this age range, and binge drinking among minority females increased. Risk for binge drinking increased among 21- to 23-year-old women, with college women outpacing nonstudents in this age range. Trends also indicate that no reduction in binge drinking occurred for college men. CONCLUSIONS Although the overall trend is toward lower rates of binge drinking among youths, likely a result of a higher legal drinking age and other changes in alcohol policy, little improvement has occurred for college students, and increases in binge drinking among women has offset improvements among youths. Understanding these specific demographic trends will help inform prevention efforts.

Partnership status and the human sex ratio at birth.

If two–parent care has different consequences for the reproductive success of sons and daughters, then natural selection may favour adjustment of the sex ratio at birth according to circumstances that forecast later family structure. In humans, this partnership–status hypothesis predicts fewer sons among extra–pair conceptions, but the rival ‘attractiveness’ hypothesis predicts more sons among extra–pair conceptions, and the ‘fixed–phenotype’ hypothesis predicts a constant probability of having a son, regardless of partnership status. In a sample of 86 436 human births pooled from five US population–based surveys, I found 51.5% male births reported by respondents who were living with a spouse or partner before the childs conception or birth, and 49.9% male births reported by respondents who were not (X2=16.77 d.f.=1 p<0.0001). The effect was not explained by paternal bias against daughters, by parental age, education, income, ethnicity or by year of observation, and was larger when comparisons were made between siblings. To my knowledge, this is the first direct evidence for conditional adjustment of the sex ratio at birth in humans, and could explain the recent decline in the sex ratio at birth in some developed countries.

The emerging link between alcoholism risk and obesity in the United States

CONTEXT The prevalence of obesity has risen sharply in the United States in the past few decades. Etiologic links between obesity and substance use disorders have been hypothesized. OBJECTIVE To determine whether familial risk of alcohol dependence predicts obesity and whether any such association became stronger between the early 1990s and early 2000s. DESIGN We conducted analyses of the repeated cross-sectional National Longitudinal Alcohol Epidemiologic Survey (1991-1992) and National Epidemiologic Survey on Alcohol and Related Conditions (2001-2002). SETTING The noninstitutionalized US adult population in 1991-1992 and 2001-2002. PARTICIPANTS Individuals drawn from population-based, multistage, random samples (N = 39 312 and 39 625). MAIN OUTCOME MEASURE Obesity, defined as a body mass index (calculated from self-reported data as weight in kilograms divided by height in meters squared) of 30 or higher and predicted from family history of alcoholism and/or problem drinking. RESULTS In 2001-2002, women with a family history of alcoholism (defined as having a biological parent or sibling with a history of alcoholism or alcohol problems) had 49% higher odds of obesity than those without a family history (odds ratio, 1.48; 95% confidence interval, 1.36-1.61; P < .001), a highly significant increase (P < .001) from the odds ratio of 1.06 (95% confidence interval, 0.97-1.16) estimated for 1991-1992. For men in 2001-2002, the association was significant (odds ratio, 1.26; 95% confidence interval, 1.14-1.38; P < .001) but not as strong as for women. The association and the secular trend for women were robust after adjustment for covariates, including sociodemographic variables, smoking status, alcohol use, alcohol or drug dependence, and major depression. Similar trends were observed for men but did not meet statistical significance criteria after adjustment for covariates. CONCLUSIONS These results provide epidemiologic support for a link between familial alcoholism risk and obesity in women and possibly in men. This link has emerged in recent years and may result from an interaction between a changing food environment and predisposition to alcoholism and related disorders.

Correspondence Between Secular Changes in Alcohol Dependence and Age of Drinking Onset Among Women in the United States

BACKGROUND Several lines of evidence suggest that the lifetime prevalence of alcohol dependence among women has increased in recent decades, but has not risen significantly for men. Early age at onset of drinking (AOD) is strongly correlated with risk for alcohol dependence and there is evidence that mean AOD has also decreased, particularly for women. The present report sought to confirm the trends in AOD and to determine the extent to which they might account for secular trends in alcohol dependence. METHODS Repeated cross-sectional analyses of data from 2 large, national epidemiological surveys were conducted to enable estimates of cross-cohort differences while controlling for age-related factors. Regression analyses were used to compute risk for alcohol dependence associated with birth cohort membership, before and after inclusion of AOD as a covariate. RESULTS Both men and women born between 1944 and 1963 had earlier ages of onset for drinking than did the earliest birth cohort analyzed (1934-43). However, the net decrease in AOD was twice as large for women (3.2 years) than that for men (1.6 years). After adjusting for AOD, differences in lifetime prevalence between different birth cohorts of women were rendered nonsignificant, indicating that AOD accounts for a substantial portion of change in the lifetime prevalence of alcohol dependence. CONCLUSIONS These results suggest that a decrease in AOD accounts for much of the increase in lifetime alcohol dependence among women. AOD is likely to be an indicator of dynamic, and therefore modifiable risk behaviors impacting risk for alcohol dependence.

The legacy of minimum legal drinking age law changes: Long-term effects on suicide and homicide deaths among women

BACKGROUND Prior to the establishment of the uniform drinking age of 21 in the United States, many states permitted legal purchase of alcohol at younger ages. Lower drinking ages were associated with several adverse outcomes, including elevated rates of suicide and homicide among youth. The objective of this study is to examine whether individuals who were legally permitted to drink prior to age 21 remained at elevated risk in adulthood. METHODS Analysis of data from the U.S. Multiple Cause of Death files, 1990 to 2004, combined with data on the living population from the U.S. Census and American Community Survey. The assembled data contained records on over 200,000 suicides and 130,000 homicides for individuals born between 1949 and 1972, the years during which the drinking age was in flux. Logistic regression models were used to evaluate whether adults who were legally permitted to drink prior to age 21 were at elevated risk for death by these causes. A quasi-experimental analytical approach was employed, which incorporated state and birth-year fixed effects to account for unobserved covariates associated with policy exposure. RESULTS In the population as a whole, we found no association between minimum drinking age and homicide or suicide. However, significant policy-by-sex interactions were observed for both outcomes, such that women exposed to permissive drinking age laws were at higher risk for both suicide (OR = 1.12, 95% CI: 1.05, 1.18, p = 0.0003) and homicide (OR = 1.15, 95% CI: 1.04, 1.25, p = 0.0028). Effect sizes were stronger for the portion of the cohort born after 1960, whereas no significant effects were observed for women born prior to 1960. CONCLUSIONS Lower drinking ages may result in persistent elevated risk for suicide and homicide among women born after 1960. The national drinking age of 21 may be preventing about 600 suicides and 600 homicides annually.