Heritability of MMPI personality indicators of psychopathology in twins reared apart

Twins Reared Apart and Twins in Families: The Findings Behind the Fascination

Dr. Irving I. Gottesman was very creative in applying twin research designs to test hypotheses and predictions about human behavior. Two designs stand out among others: twins reared apart from birth and the twin-family study. I (NS) was inspired to incorporate both of these approaches into my own research programs at California State University, Fullerton. Gottesman's involvement and contributions to reared-apart twin research are described, followed by selected findings from the Minnesota Study of Twins Reared Apart (MISTRA), the Fullerton Study of Chinese Twins Reared Apart (CTA), a case report on separated monozygotic (MZ) female twins from South Korea, and doubly exchanged MZ male twin pairs from Colombia, South America. Recent findings from an ongoing twin-family study of social closeness, and future directions, are also presented.

Brain alterations potentially associated with aggression and terrorism

A large proportion of the persons who join terrorist groups as well as lone-acting terrorists have a history of violent behavior or mental disorder that predated their becoming terrorists. This suggests that brain alterations found to occur in violent perpetrators may also be present in a significant percentage of terrorists. After a short delineation of phylogenetically old neuronal networks that are important for the generation of aggressive behavior in inconspicuous brains, this review summarizes structural and functional brain-imaging studies in violent offenders published over the last 10 years. Depending on the subtype of violence (impulsive or instrumental), deviations in structure or function were mainly found in the prefrontal, orbitofrontal, and insular cortex, as well as in temporolimbic structures (e.g., the amygdala, hippocampus, and parahippocampus). These brain areas are essentially responsible for the control of the archaic neuronal generators of aggression located in the hypothalamus and limbic system. This regional distribution of brain alterations also shows a remarkable overlap with those brain regions that are crucial for such prosocial traits as empathy and compassion. Feelings of superiority, dominance, and satisfaction gained by performing violent and terroristic attacks suggest that a hedonistic component via an activation of brain reward systems plays an additional role. In our current debate about the causes of terrorism, aspects of brain dysfunction should receive more attention.

The Recaptured Scale Technique: A Method for Testing the Structural Robustness of Personality Scales

Tellegen and Waller advocated a complex and time-consuming scale construction method that they called "exploratory test construction." Scales that are constructed by this method-such as the Multidimensional Personality Questionnaire (MPQ)-are presumed to be more "psychologically coherent" and "robust" than scales constructed by other means. Using a novel procedure that we call the "recaptured scale technique," we tested this conjecture by conducting a megafactor analysis on data from the 411 adult participants of the Minnesota Study of Twins Reared Apart who completed the MPQ, the MMPI, and the CPI. We extracted and obliquely rotated 21 factors from a matrix of gender-corrected tetrachoric correlations for the 1,102 nonredundant items of the three omnibus inventories. Robustness of the 11 MPQ scales was assessed by the degree to which these factors recaptured the MPQ item groupings. Our results showed that nine factors were clearly recognizable as MPQ scales and two additional factors represented a bifurcation of an MPQ scale. A higher-order factor analysis of all 21 factor scales yielded five factors that clearly resembled the Big Five. Our results provide strong support for (a) the method of exploratory test construction, (b) the structural robustness of most MPQ scales, and

Family background of modern health worries, somatosensory amplification, and health anxiety: A questionnaire study

In the development of somatosensory amplification, health anxiety, and modern health worries, environmental factors seem more important than genetic background. Parental attitudes might represent a major source of learning. In total, 186 adolescents and their parents completed a questionnaire assessing modern health worries, somatosensory amplification, health anxiety, and somatic symptoms. Adolescents’ modern health worries, somatosensory amplification, and health anxiety were positively related to respective parental characteristics in regression analyses even after controlling for sociodemographic variables and somatic symptoms. Parental beliefs may play a role in the development of these characteristics.

Stability in MMPI among adoptees with high and low genetic risk for schizophrenia and with low Communication Deviance of their adoptive parents

Stability has been considered an important aspect of vulnerability to schizophrenia. The temporal stability of the scales in the Minnesota Multiphasic Personality Inventory (MMPI) was examined, using adoptees from the Finnish Adoptive Family Study of Schizophrenia. Adoptees who were high-risk (HR) offspring of biological mothers having a schizophrenia spectrum disorder (n=28) and low-risk (LR) controls (n=46) were evaluated using 15 MMPI scales at the initial assessment (HR, mean age 24 years; LR, mean age 23 years) and at the follow-up assessment after a mean interval of 11 years. Stability of the MMPI scales was also assessed in the groups of adoptees, assigned according to the adoptive parents'(n=44) communication style using Communication Deviance (CD) scale as an environmental factor. Initial Lie, Frequency, Correction, Psychopathic Deviate, Schizophrenia, Manifest Hostility, Hypomania, Phobias, Psychoticism, Religious Fundamentalism, Social Maladjustment, Paranoid Schizophrenia, Golden-Meehl Indicators, Schizophrenia Proneness and 8-6 scale scores significantly predicted the MMPI scores at the follow-up assessment indicating stability in the characteristics of thinking, affective expression, social relatedness and volition. Low CD in the family had an effect on the stabilization of personality traits such as social withdrawal and restricted affectivity assessed by Correction and Hostility.

Intrinsic and extrinsic religiousness: genetic and environmental influences and personality correlates

This report presents findings for the Intrinsic (IR) and Extrinsic (ER) religiousness scales from the Minnesota Study of Twins Reared Apart. The scales were shown to be internally consistent, sufficiently distinct from the scales of the California Psychological Inventory and the Multidimensional Personality Questionnaire and unrelated to a number of measures of response style to justify treating them as distinct traits. The I scales also showed considerable evidence of construct validity in its correlations with religious fundamentalism and authoritarianism as assessed by the MMPI and Altemeyer's Right-Wing Authoritarianism scale. Data on IR and ER from 35 pairs of monozygotic twins reared apart (MZA) and 37 pairs of dizygotic twins reared apart (DZA) were fitted to a biometric model and demonstrated significant heritability (0.43 and 0.39), with a model containing genetic plus environmental factors fitting significantly better than a model containing only an environmental component. Twin similarity could not be explained by placement on a self-reported measure of family Moral Religious Emphasis as measured by the Family Environment Scale.

Individual differences in adolescent religiosity in Finland: familial effects are modified by sex and region of residence

Data from 16-year-old Finnish twin pairs were used to estimate familial effects on religiosity and the modification of those effects by sex and residential region. The sample of 2265 twin boys and 2521 twin girls formed 779 monozygotic and 1614 dizygotic pairs, 785 of the same sex and 829 of opposite sex. We compared religiosity scores of twins living in more rural and traditional northern Finland with those living in the more urban and secular southern region. Girls had higher religiosity scores than did boys, and twins living in northern Finland had higher religiosity scores than those resident in southern Finland. Correlations for monozygotic twins were slightly higher than those for dizygotic twins, and covariance modeling found modest heritability of religiosity [11% (95% CI 0–24) for girls; 22% (95% CI 6–38) for boys], and substantial shared environmental effects [60% (95% CI 49–69) and 45% (95% CI 31–57)] among girls and boys, respectively. The correlation between shared environmental effects in boys and girls was estimated to be 0.84 (95% CI 0.73–0.99). In analyses distinguishing region of residence, girls living in southern Finland were found to have significantly higher unshared environmental effects than girls in northern Finland, while boys living in the urban south appeared to have lower shared environmental effects, and higher additive genetic effects, than boys living in the rural north.

Genetic and environmental influences on impulsivity: a meta-analysis of twin, family and adoption studies

A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a significant moderator of the genetic and environmental influences on impulsivity. These results provide a structured synthesis of existing behavior genetic studies on impulsivity by providing a clearer understanding of the relative genetic and environmental contributions in impulsive traits through various stages of development.

Personality characteristics of mothers of children with attention deficit hyperactivity disorder as assessed by the Minnesota multiphasic personality inventory

OBJECTIVE

The current study investigated the personality characteristics of mothers of children with attention deficit hyperactivity disorder (ADHD) using the Minnesota Multiphasic Personality Inventory (MMPI).

METHODS

Fifty mothers (average age of 38.1+/-4.2 years) of children with ADHD not having comorbidity (37 boys, 13 girls; average age of 8.5+/-1.9 years) and 59 mothers (average age of 38.1+/-2.7 years) of comparison children (37 boys, 13 girls; average age of 8.1+/-1.5 years) completed the Korean version of the MMPI. Only mothers whose psychiatric health was verified by the Structured Clinical Interview for axis-I DSM-IV disorders (SCID-IV) were included in current study.

RESULTS

After controlling for maternal age, maternal education level, children's gender, age, and total and verbal intelligence quotient (IQ), the MMPI scores of the mothers of children with ADHD were significantly higher on the depression (D), hysteria (Hy) and psychasthenia (Pt) scales than those of the mothers of children in the comparison group.

CONCLUSION

These results suggested that even psychologically healthy mothers of children with ADHD alone might be depressed, histrionic and anxious.

MMPI Vulnerability Indicators for Schizophrenia and Attention Deficit Disorder: UCLA Family Study of Biological Parents of Offspring with Childhood-Onset Schizophrenia or ADHD

Minnesota Multiphasic Personality Inventory (MMPI) scores were examined for 50 parents of children with an onset of schizophrenia prior to 14 years of age, 153 parents of children with attention deficit hyperactivity disorder (ADHD), and 168 parents of community comparison children. The parents were participants in the UCLA Family Study. The mean scores on all standard MMPI scales were within normal limits for all three groups of participants. Parents of schizophrenia probands were significantly higher on scale Sc than parents of community comparison children. Previous research has shown that scale Sc may be associated with a genetic liability to developing schizophrenia. Thus, scale Sc shows promise as an indicator of a heightened risk for the development of schizophrenia. The parents of the ADHD probands were significantly higher on standard clinical scale Pd than community comparison parents. Mothers of both schizophrenia and ADHD probands shared some personality indicators of stress reactivity. Although this study, like all non-adoptee family studies, cannot disentangle genetic effects on the development of these personality characteristics from environmental effects, we speculate that the emotional distress resulting in higher levels of the MMPI characteristics seen in the patients' mothers reflects the impact of raising a psychiatrically ill offspring.

Genetic and Environmental Influences on Antisocial Behaviors: Evidence from Behavioral–Genetic Research

This article reviews behavioral-genetic research into human antisocial behavior. The focus is on studies of antisocial behavior that have been leading the way in investigating environmental and genetic influences on human behavior. The first generation of studies, which provided quantitative estimates attesting that genes and environments each influence about half of the population's variation in antisocial behaviors is interpreted. Then how behavioral-genetic methods are being applied to test developmental theory and to detect environmental causes of antisocial behavior is illustrated. Evidence for interactions between genes and the environment in the etiology of antisocial behavior is also examined. The article ends by envisioning future work on gene-environment interplay in the etiology of antisocial behavior.

Twin studies in behavioral research: a skeptical view

We review in detail two major ongoing research projects that employ samples of twins reared apart (and in one case, twins reared together). The studies attempt, via model fitting, to estimate proportions of genetic and environmental variance for many human traits. We discuss problems concerning the representativeness of samples, the accuracy and reliability of the data, the extent of contact of nominally separated twins, the measurement of selective placement effects, and the particular model-fitting procedures. The two studies agree in their conclusions, but we do not find the conclusions to be convincing. We suggest that no scientific purpose is served by the flood of heritability estimates generated by these studies.

Genetic and environmental influences on human behavioral differences

Human behavioral genetic research aimed at characterizing the existence and nature of genetic and environmental influences on individual differences in cognitive ability, personality and interests, and psychopathology is reviewed. Twin and adoption studies indicate that most behavioral characteristics are heritable. Nonetheless, efforts to identify the genes influencing behavior have produced a limited number of confirmed linkages or associations. Behavioral genetic research also documents the importance of environmental factors, but contrary to the expectations of many behavioral scientists, the relevant environmental factors appear to be those that are not shared by reared together relatives. The observation of genotype-environment correlational processes and the hypothesized existence of genotype-environment interaction effects serve to distinguish behavioral traits from the medical and physiological phenotypes studied by human geneticists. Behavioral genetic research supports the heritability, not the genetic determination, of behavior.

What do the MMPI scales fundamentally measure? Some hypotheses

I consider the question of whether all psychopathological behaviors can, on an evolutionary foundation, be considered as positive adaptations. I proposed that higher functions can be differentiated from their associated emotional modulations at simultaneous subjective, behavioral, and neural levels and that organizing analyses in this way will enable us to fill in our understanding of both the effects and relief of traumatic experiences. I then present each of the 8 clinical scales of the MMPI (Hathaway & McKinley, 1943) as a dimension of positive adaptation with simultaneous cognitive-emotional, operant-classical, and neocortical-limbic elements. A variety of life-experience paradigms are then offered to explain the factors that operate to increase MMPI scale elevations as well as countermeasures that can operate to reduce such elevations. Understanding all such behaviors as adaptive leads to a notable enhancement of empathy.

Heritability of MMPI Harris-Lingoes and Subtle-Obvious subscales in twins reared apart

A large sample of identical and fraternal twins who had been reared apart was used to examine the genetic and environmental architecture of the MMPI Subtle-Obvious and Harris-Lingoes subscales. Univariate genetic analyses indicated significant heritability for all 28 of the Harris-Lingoes subscales (estimates ranged from.23 to.61), all five Obvious subscales (estimates ranged from.37 to.56) and four of the five Subtle subscales (estimates ranged from.27 to.35). Two randomly constructed scales were analyzed as controls; neither of these scales showed significant heritability. Exploratory correlational findings suggested that three of the Wiener-Harmon Subtle subscales may tap aspects of psychological health, naivete, or repression. Ma-S may come closest to Wiener and Harmon s intent. Although they apparently diverge from their original purpose, it may be too early to abandon the low face valid items of the Subtle subscales.

Etiology of the impulsivity/aggression relationship: genes or environment?

Genetic and environmental influences on the phenotypic relationship between the Barratt Impulsiveness Scale and the aggression scales from the Buss-Durkee Hostility Inventory in adult males were examined. This study used 182 pairs of male MZ twins and 118 pairs of male DZ twins from the Vietnam Era Twin Registry. Phenotypic relationships between the measure of impulsivity and subscales of the measure of aggression (direct assault, verbal assault, indirect assault, and irritability) ranged from 0.22 to 0.51. Genetic and environmental mediation of the phenotypic relationship between impulsivity and aggression were approximately the same for all four models. Multivariate model-fitting analysis indicated that irritability and impulsivity had a larger phenotypic relationship, as well as a greater portion of shared genes and environment than the other three subscales of aggression. This suggests, for example, that there are more overlapping genetic and environmental influences accounting for the relationship between irritability and impulsivity than between direct assault and impulsivity. The effects of such findings on our understanding of impulsive aggression are discussed.

Schizophrenia genetics at the millennium: cautious optimism

As the new millennium approaches, research into the genetic aspects of schizophrenia has already made an impressive start toward an integrated model which is discovering roles for genetic agents, environmental agents and experiences, and chance factors. The best model follows that proposed for understanding such complex diseases as coronary artery disease and diabetes. Genetic information has come from both genetic epidemiology and molecular genetics. Evidence for gene regions on 6p and 8p gives the strongest support for harboring schizophrenia susceptibility genes, based on international collaborative studies that "generally" replicate one another; evidence for regions on 3p, 5q, 9p, 20p, and 22q, while less compelling, will encourage focused work. Determining the steps between the regions and the phenotype will challenge the next generation of scientists.

Behavioral genetics '97: ASHG statement. Recent developments in human behavioral genetics: past accomplishments and future directions

The field of behavioral genetics has enormous potential to uncover both genetic and environmental influences on normal and deviant behavior. Behavioral-genetic methods are based on a solid foundation of theories and methods that successfully have delineated components of complex traits in plants and animals. New resources are now available to dissect the genetic component of these complex traits. As specific genes are identified, we can begin to explore how these interact with environmental factors in development. How we interpret such findings, how we ask new questions, how we celebrate the knowledge, and how we use or misuse this knowledge are all important considerations. These issues are pervasive in all areas of human research, and they are especially salient in human behavioral genetics.