Article 670 Am J Psychiatry 161:4, April 2004 http://ajp.psychiatryonline.org The Effect of Parental Alcohol and Drug Disorders on Adolescent Personality Irene J. Elkins, Ph.D. Matt McGue, Ph.D. Steve Malone, Ph.D. William G. Iacono, Ph.D. Objective: The relationship of parental alcohol or drug diagnosis to offspring personality was examined in a population- based sample of 17-year-old twins (568 girls and 479 boys) participating in the Minnesota Twin Family Study. Whether off- spring personality characteristics 1) are spe- cific to the type of substance use disorder in parents (alcohol versus drug) and 2) are found in high-risk offspring without substance use disorders as well as in off- spring with substance use disorders was investigated. Method: Personality was assessed with the Multidimensional Personality Ques- tionnaire substance use disorders were assessed in person through diagnostic interviews. Results: In both male and female off- spring, parental history of alcohol depen- dence was associated with greater nega- tive emotionality, aggression, stress reaction, and alienation but lower well- being parental history of drug disorders was associated with lower constraint, con- trol, harm avoidance, and traditionalism but higher social potency. Excluding off- spring with a substance use disorder had virtually no effect on the statistical signifi- cance of these findings. Conclusions: In contrast to findings in some adult samples, personality char- acteristics associated with a family history of substance use disorders are found even in adolescent offspring who have not yet developed these disorders themselves, suggesting that personality might be one indicator of familial risk for substance use disorders during this developmental stage. Personality profiles of offspring of parents with substance use disorders also show some diagnostic specificity, with constraint associated with parental drug abuse and negative emotionality with pa- rental alcoholism. (Am J Psychiatry 2004 161:670���676) A lcohol and drug disorders show strong familial transmission (1). Twin studies have consistently demon- strated a substantial genetic component to both alcohol- ism (2, 3) and illicit drug abuse and dependence (4, 5). An obvious risk factor for a genetically influenced disorder is having a parent with the disorder. Although strong envi- ronmental influences have also been implicated by twin research, research in adoptive samples has generally found that being reared by an alcoholic parent does not significantly increase the risk for alcoholism in adopted offspring (6, 7). More research is needed to identify what other characteristics might aid in the early identification of those at risk in order to help prevent the development of these disorders. Along these lines, it has been suggested that personality might represent a common mediating factor for alcohol- ism risk due to parental history (8). Like substance use dis- orders, personality has consistently been found to be moderately heritable (9). Behavioral disinhibition (i.e., novelty-seeking, impulsivity, lack of constraint) and nega- tive emotionality (the tendency to experience negative mood states) are the personality traits most often impli- cated with alcoholism (10), and there is evidence that common genetic factors may underlie both these person- ality traits and alcoholism (11). Longitudinal studies have confirmed prospectively that indicators of behavioral dis- inhibition predict both early onset of substance use (12) and alcohol problems in early adulthood (13), although support for negative emotionality as a prospective predic- tor of substance use disorders is less consistent (14). In contrast, a recent report based on 325 probands and 262 of their first-degree adult relatives (15) concluded that personality traits did not constitute familial or heritable risk factors for substance use disorders. Both probands and relatives with alcohol and drug disorders showed per- sonality differences from those without substance use dis- orders. However, the relatives of probands with substance use disorder diagnoses but who did not have these disor- ders themselves did not. The sample consisted mostly of middle-aged adults who were beyond the age of risk for developing a substance use disorder. Whether the same lack of personality deviations might be observed in at-risk relatives who were free of substance use disorders at an earlier point in development is not clear. Furthermore, although both alcohol and drug disorders were included by Swendsen et al. (15), how personality factors might differ based on type of disorder was not a fo- cus of the investigation. Despite the high comorbidity of

Am J Psychiatry 161:4, April 2004 671 ELKINS, MCGUE, MALONE, ET AL. http://ajp.psychiatryonline.org alcoholism with drug dependence (16), the personality factors that are specific to alcoholism alone or that are due to comorbidity with drug disorders have received little at- tention. What differentiates these disorders was examined in the parents of twins in the Minnesota Twin Family Study (17). Adults with a history of drug diagnosis, including those with comorbid alcoholism, were found to be low in constraint. However, those with alcoholism alone were not low in constraint but, rather, were high in negative emotionality. These results raise the possibility that previ- ous findings associating behavioral disinhibition with al- coholism may have been due to the subset of alcoholics who abuse other drugs. Whether these specific profiles characterizing alcohol versus drug disorders extend to off- spring or were simply a consequence of substance use dis- orders was not explored. The present investigation used a large representative sample of older adolescent offspring, careful documenta- tion of substance use disorders by means of direct inter- view, and a comprehensive measure of personality to ask the following questions: 1. How is a parental alcohol or drug diagnosis related to offspring personality? 2. Do alcohol and drug disorders in parents confer the same, or different, personality risks to offspring? 3. Are these relationships primarily found in offspring who already have a substance use disorder, or do high-risk offspring who have not yet developed a substance use disorder also show these personality deviations? This last question is particularly crucial because it con- trols for the possibility that personality traits can be con- sequences, rather than precursors, of substance use dis- orders (15). Finally, because alcohol and drug disorders are more prevalent in men than women (18) and person- ality characteristics are associated with gender (19), gen- der differences in the relationships just described were also assessed. Method The initial sample consisted of 674 girls and 578 boys from 626 twin pairs reared together who visited the Minnesota Twin Family Study with their parents. The Minnesota Twin Family Study is a longitudinal study designed to identify genetic and environmen- tal factors that influence the development of substance abuse and related psychopathology (20). The study used a population-based ascertainment method in which all same-sex twin pairs born in the state of Minnesota in specified years were identified by public birth records, located (current addresses of over 90% of the twin births were established by using various public registries), then recruited to visit when the twins reached either age 11 or 17. For the present investigation, only data from the intake visit of twins in the 17-year-old cohort (mean age at assessment=17.5 years, SD=0.5) were used. Families were excluded from participation if the twins lived more than a day���s drive from Minneapolis, had been adopted, or had a physical or intellectual disability that pre- cluded completing our daylong, in-person assessment. Of the el- igible twin families, approximately 17% refused to participate. After a complete description of the study was given, written informed consent was obtained from the parents, and written assents were obtained from the twins. Among the 626 initial families, all biological mothers and 88% (N=548) of the biological fathers completed an intake assessment. On the basis of responses to a brief telephone or mail survey (completed on over 80% of the ineligible or refusing families), the parents in the participating families differed minimally from the nonparticipants on socioeconomic status indicators (e.g., 0.3 years more education for the participants). They did not differ at all in self-reported rates of psychopathology (see reference 20 for a complete description of the sample and recruitment). Further- more, because twins are neither systematically different in per- sonality (21) nor in rates of psychopathology (22) from single off- spring, the sample should be representative of the population of Minnesota. Mean years of education were 13.7 (SD=1.9) for the mothers and 14.2 (SD=2.3) for the fathers. Consistent with Min- nesota demographics for the birth years sampled, 97% of the mothers and fathers were Caucasian. Diagnostic and Personality Assessment All twins, mothers, and fathers were interviewed separately at the University of Minnesota by different interviewers (with no knowledge of other family members��� status) regarding a variety of psychological disorders. Interviewers had a B.A. or an M.A. in psy- chology and went through extensive training and observation. Both parents and twins were assessed for alcohol and illicit drug disorders (i.e., amphetamines, cannabis, cocaine, hallucinogens, inhalants, opiates, phencyclidine, or sedatives) by using a modi- fied version of the expanded substance abuse module of the Composite International Diagnostic Interview (23). For the small number of parents who were unavailable (e.g., because of death) or unwilling to participate (12% of the fathers), substance use dis- orders in the unavailable parent were assessed by means of spou- sal report with a modified version of the Family Informant Sched- ule and Criteria (24). Maternal reports of substance use disorders in the twins were also obtained by using a modified parent ver- sion of the Diagnostic Interview for Children and Adolescents (25), and a symptom was considered present if either the mother or twin reported it as present. Lifetime diagnoses based on DSM- III-R criteria (the diagnostic system in use when the Minnesota Twin Family Study began) were determined by teams of two ad- vanced clinical psychology graduate students, and symptoms were assigned based on consensus between the two diagnosti- cians. Reliability of the consensus diagnoses of substance use dis- orders was 0.92 or greater (20). Personality was assessed with the 198-item version of the Mul- tidimensional Personality Questionnaire (26). The Multidimen- sional Personality Questionnaire is a self-report personality in- strument developed through factor analysis to assess a broad range of personality characteristics in normal populations. Inter- nal consistency reliabilities for the Multidimensional Personality Questionnaire range from 0.76 to 0.89, and 30-day test-retest reli- abilities range from 0.82 to 0.92. Eleven primary personality char- acteristics are assessed, and scores on 10 of these scales contrib- ute to scores on three superfactors. Positive emotionality refers to the tendency to view life as essentially a pleasurable experience and to be actively engaged socially. It consists of four primary scales (descriptions of high scorers are in parentheses): well-be- ing (cheerful, feels good about self), social potency (forceful, likes to influence and lead others), achievement (works hard, likes de- manding projects), and social closeness (sociable, likes people, affectionate). Negative emotionality, a propensity to experience psychological distress and negative mood states, consists of three primary scales: stress reaction (nervous, easily upset, irritable), alienation (feels mistreated, thinks others intend harm), and ag-