Birth Cohorts Of Finnish Twins Research Articles

“Holy anorexia”—relevant or relic? Religiosity and anorexia nervosa among Finnish women

Since medieval times, an association between religiosity and anorexia nervosa has been suggested, but few systematic studies exist. This study examines in a nationwide setting whether personal or family religiosity is associated with lifetime anorexia nervosa among women in adolescence and early adulthood. Women (N = 2,825) from the 1975 to 1979 birth cohorts of Finnish twins were screened for lifetime DSM-5 anorexia nervosa (N = 92). Parental religiosity was assessed by self-report when the women were aged 16 years. The women self-reported their religiosity at ages 16 and 22 to 27 years. Parental religiosity did not increase the risk of lifetime anorexia nervosa, and neither did religiosity of the women themselves in adolescence. In early adulthood, a J-shaped curve was compatible with the data, indicating increased risk both at low and high levels of religiosity, but this result was statistically non-significant. Religiosity was weakly negatively correlated with body dissatisfaction. There was some suggestive evidence for socioregional variation in the association of religiosity with lifetime anorexia nervosa. In this first population study to directly address religiosity and anorexia nervosa, no evidence was found for a significant association of religiosity with anorexia nervosa either at the personal or family level. Some regional differences are possible. A modest protective association of religiosity with body dissatisfaction is also possible. Despite compelling case descriptions of "holy anorexia," religiosity does not appear to be a central factor in the development of anorexia nervosa in Finland, a highly secularized Christian country.

Other specified and unspecified feeding or eating disorders among women in the community.

To examine the occurrence, course, and clinical picture of the DSM-5 residual categories 'Other Specified Feeding or Eating Disorder' (OSFED) and 'Unspecified Feeding or Eating Disorder' (UFED), to describe potential subtypes, and to evaluate whether the subdivision of the residual category appears meaningful. We screened women from the 1975-79 birth cohorts of Finnish twins (N = 2825) for lifetime eating disorders using questionnaires and the SCID interview. This analysis characterizes women who reported clinically significant eating disorder symptoms but did not fulfill diagnostic criteria for DSM-5 anorexia nervosa (AN), bulimia nervosa (BN), or binge eating disorder (BED). Thirty-eight women (21% of those with an eating disorder) fell in the residual OSFED/UFED category. A third of them (N = 14) fulfilled OSFED criteria, whereas two thirds (N = 24) fell in the UFED category. The lifetime prevalence of OSFED/UFED was 1.5% (95% CI 1.1-2.0%), less than half of the prevalence of DSM-IV eating disorder not otherwise specified (EDNOS). The mean age of onset of OSFED/UFED was 18 years, median duration of symptoms was two years, and the 5-year probability of recovery was 60%. Over a third of women with OSFED/UFED suffered from comorbid psychiatric disorders. Both residual categories were clinically heterogeneous and included atypical forms of AN, BN, and BED. Applying the DSM-5 criteria in a community sample of young women more than halved the occurrence of residual eating disorder diagnoses, but resulted in two instead of one clinically heterogeneous residual categories. Nevertheless, residual eating disorders were associated with considerable clinical severity. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:1010-1017).

The Eating Disorder Inventory in the screening for DSM-5 binge eating disorder

BackgroundWe assessed whether the Eating Disorder Inventory (EDI) is suitable for screening binge eating disorder (BED) in young women. MethodYoung women (N=2825) from the 1975–79 birth cohorts of Finnish twins were assessed by questionnaires, including subscales of the EDI. For a subset of women (N=548), we established DSM-5 diagnoses of BED; 16 women had lifetime BED. We compared screening properties of the EDI scales using receiver operating characteristic (ROC) analysis, determined optimal cutoff points, and calculated sensitivities and specificities. ResultsThe best screen for DSM-5 BED was the global score of three subscales (Bulimia, Drive for Thinness, Body Dissatisfaction) with an area under the curve (AUC) of 0.86. Its sensitivity was 87% and specificity 76% at cutoff ≥21. Three individual subscales had acceptable screening properties: Bulimia (AUC 0.83; sensitivity 80%, specificity 78% at cutoff ≥2), Drive For Thinness (AUC 0.82; sensitivity 87%, specificity 72% at cutoff ≥7), and Body Dissatisfaction (AUC 0.81; sensitivity 93%, specificity 60% at cutoff ≥8). ConclusionThe EDI performed well as a screening tool for BED in our community-based sample of young twin women. Future studies should assess its value in other populations and in clinical settings.

Risky drinking behaviors among women with eating disorders-A longitudinal community-based study.

Eating disorders and alcohol use disorders often co-occur, but few prospective studies have examined their relationship. Using a large population-based twin sample, we investigated how the drinking behaviors of women with lifetime eating disorders unfold from adolescence to adulthood. We identified 182 women with a lifetime eating disorder assessed at mean age 24, including 92 women with DSM-5 anorexia nervosa and 58 women with DSM-5 bulimia nervosa, from the 1975-1979 birth cohorts of Finnish twins (N = 2,825 women). Frequency of drinking and intoxicating were assessed at ages 16, 24, and 34. Drinking problems were assessed at ages 24 and 34 by the Malmö-modified Michigan Alcohol Screening Test (Mm-Mast) and the Rutgers Alcohol Problem Index (RAPI). At age 16, proportionately more women with eating disorders reported being severely intoxicated when they last drank (25% vs.16%, P = 0.001), and at both surveys in adulthood, they reported more frequent intoxication and more alcohol-related problems than their unaffected peers. Those who had recovered from their eating disorder at age 24 still reported more alcohol-related problems in their 30s than did other women. The age of drinking onset, number of monthly drinking days, or frequency of intoxication in adolescence did not differ between women with lifetime eating disorders and unaffected women. Women with eating disorders scored higher than their unaffected peers on scales measuring alcohol dependence, alcohol-related problems, and intoxication. These differences persisted from mid-adolescence into young adulthood. Women with eating disorders should be assessed routinely for drinking behaviors. © 2016 Wiley Periodicals, Inc. (Int J Eat Disord 2016; 49:563-571).

Premorbid Depression Associated With Poor Anorexia Prognosis

Back to table of contents Previous article Next article Clinical and Research NewsFull AccessPremorbid Depression Associated With Poor Anorexia PrognosisJoan Arehart-TreichelJoan Arehart-TreichelSearch for more papers by this authorPublished Online:14 Apr 2014https://doi.org/10.1176/appi.pn.2014.4a9AbstractSomeone with both anorexia and depression can be ill for longer and less likely to recover than someone with anorexia alone, suggesting that depression is a severity marker for anorexia.Premorbid depression is associated with a poor prognosis in anorexia nervosa, European and American researchers reported in the March International Journal of Eating Disorders.Anna Keski-Rahkonen, M.D., Ph.D.: “I think we should accept that anorexia patients with psychiatric comorbidities will be some of our most challenging patients.”Anna Keski Rahkonen, M.D., Ph.D.The lead researcher was Anna Keski-Rahkonen, M.D., Ph.D., an assistant professor in psychiatric epidemiology at the University of Helsinski in Finland.Out of 2,881 women from the 1975 to 1979 birth cohorts of Finnish twins, the researchers identified 55 with a lifetime DSM-IV diagnosis of anorexia nervosa. Of these women, who were age 26 on average at the time of assessment, 39 had recovered from their eating disorder, and 16 had not. Recovery was defined as restoration of weight, menstruation, and the absence of binging and purging for at least one year prior to assessment. Among the women classified as recovered, the average duration of recovery was seven years.The unrecovered women were significantly more likely to suffer from depressive symptoms prior to eating-disorder onset, to be unemployed, to be dissatisfied with their current partner or spouse, and to report a high level of perfectionism than were women who had recovered. When age at onset and illness duration were accounted for in the analyses, however, premorbid depression was the sole prognostic factor significantly associated with a decreased likelihood of recovery.“While our theoretical understanding of the factors that may contribute to the unusual persistence of anorexia nervosa has evolved over the years, our ability to predict and manage chronicity among those who suffer from this devastating illness remains limited,” said Michael Devlin, M.D., co-director of eating disorders research at the New York State Psychiatric Institute, in an interview with Psychiatric News. “This important study brings us a step closer by underscoring the negative impact of depressive symptoms on the goal of full long-term behavioral recovery.”Commenting on the implication of their findings for psychiatrists, Keski-Rahkonen said, “Major depressive disorder is a severity marker for anorexia nervosa. This means that someone with both anorexia and depression can be ill for longer and is less likely to recover than someone with just anorexia. “We psychiatrists often look for simple solutions to complex problems. Many psychiatrists hope that a single treatment approach—say, cognitive-behavioral therapy [CBT] or an antidepressant—would relieve both anorexia and depression. Unfortunately, it seems that antidepressive medication does not alleviate symptoms of anorexia, and many patients with anorexia drop out of CBT.” She noted that she and her colleagues are conducting a study of adolescents with anorexia nervosa and are finding that “if they also have depression, they seem to need more inpatient treatment and more outpatient and emergency room visits; the overall length of treatment appears to be almost four times longer if depression is involved.“So I think we should accept that anorexia patients with psychiatric comorbidities will be some of our most challenging patients, and their treatment may require a combination of different approaches and a lot of patience.”The researchers also noted that other studies have found that depressive disorders sometimes precede anorexia nervosa and that depressive disorders are “cross-transmitted” in families with eating disorders. Asked about possible genetic connections between depression and anorexia nervosa, Keski-Rahkonen said, “Major genetic collaborations have to date failed to find susceptibility genes for both depression and anorexia. There is, however, some previous evidence from twin studies that anorexia and depression might share a genetic link.”The study was funded by the U.S. National Institutes of Health, the European Union, the Academy of Finland, and private foundations. ■An abstract of “Factors Associated With Recovery From Anorexia Nervosa: A Population-Based Study” can be accessed here. ISSUES NewArchived

Adipocyte morphology and implications for metabolic derangements in acquired obesity

Adipocyte size and number have been suggested to predict the development of metabolic complications in obesity. However, the genetic and environmental determinants behind this phenomenon remain unclear. We studied this question in rare-weight discordant (intra-pair difference (Δ) body mass index (BMI) 3-10 kg m(-2), n=15) and concordant (ΔBMI 0-2 kg m(-)(2), n=5) young adult (22-35 years) monozygotic twin pairs identified from 10 birth cohorts of Finnish twins (n=5 500 pairs). Subcutaneous abdominal adipocyte size from surgical biopsies was measured under a light microscope. Adipocyte number was calculated from cell size and total body fat (D × A). The concordant pairs were remarkably similar for adipocyte size and number (intra-class correlations 0.91-0.92, P<0.01), suggesting a strong genetic control of these measures. In the discordant pairs, the obese co-twins (BMI 30.6 ± 0.9 kg m(-2)) had significantly larger adipocytes (volume 547 ± 59 pl), than the lean co-twins (24.9 ± 0.9 kg m(-)(2); 356 ± 34 pl, P<0.001). In 8/15 pairs, the obese co-twins had less adipocytes than their co-twins. These hypoplastic obese twins had significantly higher liver fat (spectroscopy), homeostatic model assessment-index, C-reactive protein and low-density lipoprotein cholesterol than their lean co-twins. Hyperplastic obesity was observed in the rest (7/15) of the pairs, obese and lean co-twins having similar metabolic measures. In all pairs, Δadipocyte volume correlated positively and Δcell number correlated negatively with Δhomeostatic model assessment-index and Δlow-density lipoprotein, independent of Δbody fat. Transcripts most significantly correlating with Δadipocyte volume were related to a reduced mitochondrial function, membrane modifications, to DNA damage and cell death. Together, hypertrophy and hypoplasia in acquired obesity are related to metabolic dysfunction, possibly through disturbances in mitochondrial function and increased cell death within the adipose tissue.

Factors associated with recovery from anorexia nervosa: A population‐based study

To examine factors associated with the outcome of anorexia nervosa among women from the general population. Women (N = 2,881) from the 1975-1979 birth cohorts of Finnish twins were screened for lifetime DSM-IV anorexia nervosa (N = 55 cases) using questionnaires and the SCID interview. Potential factors associated with the likelihood of recovery were addressed in the same assessment. Recovery was defined as restoration of weight, menstruation, and the absence of bingeing and purging for at least one year prior to assessment. Using two-tailed t tests and Pearson's chi-square tests, we contrasted recovered (N = 39) and unrecovered (N = 16) women. We then used logistic regression adjusted for duration of illness and Cox proportional hazard models to account for the variable lengths of illness on prognostic factors. Unrecovered women were more likely to suffer from depressive symptoms prior to eating disorder onset (18.8% vs. 2.6%, p = 0.04), remain unemployed (18.8% vs. 2.6%, p = 0.04), report dissatisfaction with their current partner/spouse (p = 0.02), and report high perfectionism (p = 0.05) than were recovered women. When duration of illness was accounted for in the analyses, premorbid depression was the sole factor significantly associated with decreased likelihood of recovery (hazard ratio 0.17, 95% confidence interval: 0.03-0.89). Predicting the course of anorexia remains fraught with difficulty, but premorbid depressive symptoms are associated with poor outcome of anorexia nervosa in the general population.

Body mass index and subjective well-being in young adults: a twin population study

BackgroundBody mass index (BMI) is associated with subjective well-being. Higher BMI is believed to be related with lower well-being. However, the association may not be linear. Therefore, we investigated whether a nonlinear (U-shaped) trend would better describe this relationship, and whether eating disorders might account for the association in young adults.MethodsFinnTwin16 study evaluated multiple measures of subjective well-being, including life satisfaction, General Health Questionnaire (GHQ-20), satisfaction with leisure time, work, and family relationships, and satisfaction with sex life in young adulthood in the 1975–79 birth cohorts of Finnish twins (n=5240). We studied the relationship between indicators of subjective well-being and BMI both in full birth cohorts and in subgroups stratified by lifetime DSM-IV eating disorders.ResultsWe found an inverse U-shaped relationship between all indicators of subjective well-being and BMI in men. There was no overall association between BMI and subjective well-being in women. However, there was an inverse U-shaped relationship between BMI and indicators of subjective well-being in women with a lifetime eating disorder and their healthy female co-twins. Subjective well-being was optimal in the overweight category.ConclusionsBoth underweight and obesity are associated with impaired subjective well-being in young men. The BMI reflecting optimal subjective well-being of young men may be higher than currently recognized. Categorization of body weight in terms of BMI may need to be reassessed in young men. BMI and subjective well-being are related in women with a lifetime eating disorder, but not in the general population of young women.

Depression and Drive for Thinness are Associated with Persistent Bulimia Nervosa in the Community

To examine psychiatric comorbidity and factors that influence the outcome of bulimia nervosa (BN) in the general population. Women from the nationwide birth cohorts of Finnish twins were screened for lifetime BN (N = 59) by using questionnaires and the Structured Clinical Interview for DSM-IV. We assessed psychiatric comorbidity and other prognostic factors. Among women with lifetime BN, the following were more common than among unaffected women: current major depressive disorder (p = 0.004), lifetime major depressive disorder (p = 0.00001) and heavy drinking (p = 0.01). Decreased likelihood of recovery was associated with a history of lifetime major depressive disorder (hazard ratio (HR) 0.44, 95% confidence interval (CI) 0.23-0.84) and high drive for thinness at time of assessment (HR 0.96, 95% CI 0.93-0.99). Heavy drinking and depression present challenges for many women with BN. Major depressive disorder emerged as the only statistically significant prognostic factor of BN in this nationwide cohort; high drive for thinness was characteristic of the persistently ill.

Association of Smoking in Adolescence With Abdominal Obesity in Adulthood: A Follow-Up Study of 5 Birth Cohorts of Finnish Twins

We studied the association of adolescent smoking with overweight and abdominal obesity in adulthood. We used the FinnTwin16, a prospective, population-based questionnaire study of 5 consecutive and complete birth cohorts of Finnish twins born between 1975 and 1979 (N = 4296) and studied at four points between the ages of 16 and 27 years to analyze the effect of adolescent smoking on abdominal obesity and overweight in early adulthood. Smoking at least 10 cigarettes daily when aged 16 to 18 years increased the risk of adult abdominal obesity (odds ratio [OR]=1.77; 95% confidence interval [CI] = 1.39, 2.26). After we adjusted for confounders, the OR was 1.44 (95% CI = 1.11, 1.88), and after further adjustment for current body mass index (BMI), the OR was 1.34 (95% CI = 0.95, 1.88). Adolescent smoking significantly increased the risk of becoming overweight among women even after adjustment for possible confounders, including baseline BMI (OR = 1.74; 95% CI = 1.06, 2.88). Smoking is a risk factor for abdominal obesity among both genders and for overweight in women. The prevention of smoking during adolescence may play an important role in promoting healthy weight and in decreasing the morbidity related to abdominal obesity.

Incidence and outcomes of bulimia nervosa: a nationwide population-based study

Little is known about the epidemiology of bulimia nervosa outside clinical settings. We report the incidence, prevalence and outcomes of bulimia nervosa using for the first time a nationwide study design. To assess the incidence and natural course and outcomes of DSM-IV bulimia nervosa among women from the general population, women (n=2881) from the 1975-79 birth cohorts of Finnish twins were screened for lifetime eating disorders using a two-stage procedure consisting of a questionnaire screen and the Structured Clinical Interview for DSM-IV (SCID). Clinical recovery was defined as 1-year abstinence from bingeing and purging combined with a body mass index (BMI) 19 kg/m2. The lifetime prevalence of DSM-IV bulimia nervosa was 2.3%; 76% of the women suffered from its purging subtype and 24% from the non-purging subtype. The incidence rate of bulimia nervosa was 300/100000 person-years at the peak age of incidence, 16-20 years, and 150/100000 at 10-24 years. The 5-year clinical recovery rate was 55.0%. Less than a third of the cases had been detected by health-care professionals; detection did not influence outcome. After clinical recovery from bulimia nervosa, the mean levels of residual psychological symptoms gradually decreased over time but many women continued to experience significantly more body image problems and psychosomatic symptoms than never-ill women. Few women with bulimia nervosa are recognized in health-care settings. Symptoms of bulimia are relatively long-standing, and recovery is gradual. Many clinically recovered women experience residual psychological symptoms after attaining abstinence from bingeing and purging.

Epidemiology and Course of Anorexia Nervosa in the Community

Most previous studies of the prevalence, incidence, and outcome of anorexia nervosa have been limited to cases detected through the health care system, which may bias our understanding of the disorder's incidence and natural course. The authors sought to describe the onset and outcomes of anorexia nervosa in the general population. Lifetime prevalences, incidence rates, and 5-year recovery rates of anorexia nervosa were calculated on the basis of data from 2,881 women from the 1975-1979 birth cohorts of Finnish twins. Women who screened positive for eating disorder symptoms (N=292), their screen-negative female co-twins (N=134), and 210 randomly selected screen-negative women were assessed for lifetime eating disorders by telephone by experienced clinicians. To assess outcomes after clinical recovery and to detect residua of illness, women who had recovered were compared with their unaffected co-twins and healthy unrelated women on multiple outcome measures. The lifetime prevalence of DSM-IV anorexia nervosa was 2.2%, and half of the cases had not been detected in the health care system. The incidence of anorexia nervosa in women between 15 and 19 years of age was 270 per 100,000 person-years. The 5-year clinical recovery rate was 66.8%. Outcomes did not differ between detected and undetected cases. After clinical recovery, the residua of illness steadily receded. By 5 years after clinical recovery, most probands had reached complete or nearly complete psychological recovery and closely resembled their unaffected co-twins and healthy women in weight and most psychological and social measures. The authors found a substantially higher lifetime prevalence and incidence of anorexia nervosa than reported in previous studies, most of which were based on treated cases. Most women recovered clinically within 5 years, and thereafter usually progressed toward full recovery.

Reliability of self-reported eating disorders: Optimizing population screening

The objective of this study was to assess whether short self-report eating disorder screening questions are useful population screening methods. We screened the female participants (N = 2881) from the 1975-1079 birth cohorts of Finnish twins for eating disorders, using several short screening questions and three Eating Disorder Inventory (EDI) subscales. Comparing these measures with clinician-conducted semi-structured diagnostic interviews (N = 549) of Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) anorexia and bulimia, we calculated their sensitivities and specificities and drew receiver operating characteristic curves to further compare these items. For current and lifetime bulimia, best tradeoffs between sensitivity and specificity were reached by addressing purging behaviors. For current and lifetime anorexia, the questions "Have you ever had anorexia" and "Has anybody ever suspected that you might have an eating disorder?" optimized tradeoffs between sensitivity and specificity. These questions generally outperformed EDI subscales. Simple screening questions, although less than ideal, are at least as good as other available instruments for community screenings.

Femininity and fertility in sisters with twin brothers: prenatal androgenization? Cross-sex socialization?

Are sisters of twin brothers behaviorally or physiologically masculinized? Prenatal exposure to their brothers' androgens and postnatal socialization experiences unique to girls growing up with twin brothers might influence their attitudes, pubertal development, and reproductive histories. To investigate, we studied age- and cohort-matched samples of Finnish sisters from same-sex and opposite-sex twin pairs. Using data from two ongoing longitudinal studies of consecutive birth cohorts of Finnish twins, we assessed pubertal development at ages 11 and 14 and endorsement of attitudes associated with femininity at age 16. We also studied fertility in Finnish women from same- and opposite-sex twin pairs born from 1958 through 1971, obtaining information on their child-bearing histories when they were ages 15 to 28. Results of each comparison were unambiguously negative: There was no evidence of differences between sisters from same- and opposite-sex twin pairs, and thus, no evidence of either androgenization or cross-sex socialization.

Drinking or Abstaining at Age 14? A Genetic Epidemiological Study

Regular drinking by age 14 years is a significant risk factor for alcoholism, and genetically informative data suggest that whether a young adolescent abstains or drinks is largely attributable to familial (or other shared) environmental factors. Three consecutive birth cohorts of Finnish twins, enrolled into a longitudinal study at age 11 to 12 years, completed a follow-up questionnaire within 3 months of their 14th birthdays. The sample included 1380 twin sisters and 1330 twin brothers at age 14, and at that age, 35.4% reported using alcohol. Genetic analyses (model-fitting of twin pair data) and epidemiological analyses (logistical regressions of data from individual twins) were conducted to examine predictive factors of drinking versus abstinence at age 14. Polychoric correlations were substantial across all same-sex twin pairs but were lower for brother-sister twins, suggesting significant influences of common environments, with some sex-specific effects. Common environmental effects were equivalent in male and female adolescents and accounted for 76% of the total variation in abstinence/drinking. Logistical regression analyses among 2206 individual twins with complete data on risk-relevant measures at both baseline and follow-up identified significant predictors of drinking or abstaining at age 14, including female sex, twin sibling of the opposite sex, accelerated pubertal development, and the twins' assessments, made at age 12, of reduced parental monitoring and a less supportive home atmosphere; drinking at age 14 was also predicted by behaviors rated by the twins' classroom teachers 2 years earlier, increasing with rated behavioral problems but decreasing with rated emotional problems. Our results show that environmental factors shared by twin siblings account for most of the variance in abstaining or drinking at age 14. We identify predictors of drinking in the adolescent twins' home environments and in their dispositional behaviors, sibling interactions, and pubertal timing.

Drinking or Abstaining at Age 14? A Genetic Epidemiological Study

Background: Regular drinking by age 14 years is a significant risk factor for alcoholism, and genetically informative data suggest that whether a young adolescent abstains or drinks is largely attributable to familial (or other shared) environmental factors. Methods: Three consecutive birth cohorts of Finnish twins, enrolled into a longitudinal study at age 11 to 12 years, completed a follow-up questionnaire within 3 months of their 14th birthdays. The sample included 1380 twin sisters and 1330 twin brothers at age 14, and at that age, 35.4% reported using alcohol. Genetic analyses (model-fitting of twin pair data) and epidemiological analyses (logistical regressions of data from individual twins) were conducted to examine predictive factors of drinking versus abstinence at age 14. Results: Polychoric correlations were substantial across all same-sex twin pairs but were lower for brother-sister twins, suggesting significant influences of common environments, with some sex-specific effects. Common environmental effects were equivalent in male and female adolescents and accounted for 76% of the total variation in abstinence/drinking. Logistical regression analyses among 2206 individual twins with complete data on risk-relevant measures at both baseline and follow-up identified significant predictors of drinking or abstaining at age 14, including female sex, twin sibling of the opposite sex, accelerated pubertal development, and the twins’ assessments, made at age 12, of reduced parental monitoring and a less supportive home atmosphere; drinking at age 14 was also predicted by behaviors rated by the twins’ classroom teachers 2 years earlier, increasing with rated behavioral problems but decreasing with rated emotional problems. Conclusions: Our results show that environmental factors shared by twin siblings account for most of the variance in abstaining or drinking at age 14. We identify predictors of drinking in the adolescent twins’ home environments and in their dispositional behaviors, sibling interactions, and pubertal timing.

Gene‐Environment Interaction in Patterns of Adolescent Drinking: Regional Residency Moderates Longitudinal Influences on Alcohol Use

Drinking frequency escalates rapidly during adolescence. Abstinence declines markedly, and drinking monthly or more often becomes normative. Individual differences in adolescent drinking patterns are large, and some patterns are predictive of subsequent drinking problems; little, however, is known of the gene-environment interactions that create them. Five consecutive and complete birth cohorts of Finnish twins, born 1975-1979, were enrolled sequentially into a longitudinal study and assessed, with postal questionnaires, at ages 16, 17, and 18.5 years. The sample included 1786 same-sex twin pairs, of whom 1240 pairs were concordantly drinking at age 16. Maximum likelihood models were fit in longitudinal analyses of the three waves of drinking data to assess changes in genetic and environmental influences on alcohol use across adolescence. Secondary analyses contrasted twin pairs residing in rural versus those in urban environments to investigate gene-environment interactions. Longitudinal analyses revealed that genetic factors influencing drinking patterns increased in importance across the 30-month period, and effects arising from common environmental influences declined. Distributions of drinking frequencies in twins residing in urban and rural environments were highly similar, but influences on drinking varied between the two environments. Genetic factors assumed a larger role among adolescents residing in urban areas, while common environmental influences were more important in rural settings. Formal modeling of the data established a significant gene-environment interaction. The results document the changing impact of genetic and environmental influences on alcohol use across adolescence. Importantly, the results also reveal a significant gene-environment interaction in patterns of adolescent drinking and invite more detailed analyses of the pathways and mechanisms by which environments modulate genetic effects.

Familial and socioregional environmental effects on abstinence from alcohol at age sixteen.

This study identifies, in genetically informative data, familial and socioregional environmental influences on abstinence from alcohol at age 16. Data are from FinnTwin 16, a population-based study of five consecutive birth cohorts of Finnish twins (N = 5,747 twin individuals), yielding 2,711 pairs of known zygosity. Measures of alcohol use, embedded into a health-habits questionnaire, were taken from earlier epidemiological research with nontwin Finnish adolescents. The questionnaire was administered sequentially to all twins as they reached age 16. Separate questionnaires, including measures of alcohol use and screening questions for alcohol problems, were received from 5,243 of the twins' parents. Abstinence from alcohol to age 16 exhibits very significant familial aggregation, largely due to nongenetic influences. Abstinence rates are influenced by socioregional variation, sibling interaction effects and parental drinking patterns. Sibling and parental influences are greater in some regional environments than in others: the relative likelihood that a twin abstains, given that the co-twin does, or that both parents do, is shown to be modulated by socioregional variation. Environmental contexts affect the likelihood of maintaining abstinence from alcohol to midadolescence, and socioregional variation modulates influences of siblings and parents. The results illustrate how genetically informative data can inform prevention research by identifying target variables for intervention efforts.