Warren B. Miller

Studies of the 48 bp repeat polymorphism of the DRD4 gene in impulsive, compulsive, addictive behaviors: Tourette syndrome, ADHD, pathological gambling, and substance abuse.

Prior studies have reported an association between the presence of the 7 repeat allele of the 48 bp repeat polymorphism of the third cytoplasmic loop of the dopamine D4 receptor gene (DRD4) and novelty seeking behaviors, attention deficit hyperactivity disorder (ADHD), Tourette syndrome (TS), pathological gambling, and substance abuse. However, other studies have failed to replicate some of these observations. To determine whether we could replicate these associations we genotyped 737 individuals from four different groups of control subjects, and 707 index subjects from four different groups of impulsive, compulsive addictive behaviors including substance abuse, pathological gambling, TS, and ADHD. Chi-square analysis of those carrying the 7 allele versus non-7 allele carriers was not significant for any of the groups using a Bonferroni corrected alpha of.0125. However, chi-square analysis of those carrying any 5 to 8 allele versus noncarriers was significant for pathological gambling (p <.0001), ADHD (p </=.01) and the total index group (p </=.0004). When the comparison included all 7 alleles the results were significant for gamblers (p <.0001), TS (p </=.003), ADHD (p </=.003), and the total group (p </=.0002). There was a significant increase in the frequency of heterozygosity versus homozygosity for all alleles for pathological gamblers (p </=.0031) and the total index group (p </=.0015), suggesting that heterosis played a role. In the substance abuse subjects a quantitative summary variable for the severity of drug dependence, based on the Addiction Severity Index, showed that the scores varied by increasing severity across the following genotypes: 44 </= heterozygotes </= 77 </= 22. Studies of other quantitative traits indicated an important role for the 2 allele and the 22, 24, and 27 genotypes. All studies indicated that the role of the DRD4 gene in impulsive, compulsive, addictive behaviors is more complex than a sole focus on the 7 versus non-7 alleles.

A framework for modelling fertility motivation in couples

We present a theoretical framework that organizes individual-level fertility motivations into a couple-level model. One feature of this framework is the Traits–Desires–Intentions–Behaviour (TDIB) sequence through which the fertility motivations of individuals produce instrumental behaviours that are designed to promote or prevent childbearing. A second feature of this framework is the cognitive capacity of individuals to perceive a partner’s motivational structure. We combine these two features into a dyad-level model that addresses interactions between partners at each step of the motivational sequence. We elaborate this model first with respect to the perception of partner’s motivational structure and second with respect to the combination of partner’s and own motivational structure. In the process we consider how couple-level processes of communication, influence, and disagreement can be measured and studied through these interactions. We conclude with a summary discussion of the framework and a consideration of the implications it has for a theory of reproductive psychology, population surveys, and family planning services.

Personality traits and developmental experiences as antecedents of childbearing motivation

Childbearing motivation may be conceptualized as based upon psychological traits and shaped by experiences during childhood, adolescence, and early adult life. This paper explores what those traits and developmental experiences are. Two measures of childbearing motivation, one positive and the other negative, are described. Using a sample of 362 married men and 354 married women, the paper systematically examines the factors associated with these measures. In addition to a set of basic personality traits, these factors include parental characteristics, teenage experiences, and a number of variables from young adult behavior domains such as marriage, education, work, religion, and parental relationships. Stepwise multiple regression analyses lead to two final constrained, simultaneous-equation regression models. These models indicate the importance of both personality traits and diverse life-cycle experiences in the development of childbearing motivation, the differential gender distribution of predictors, and the different experiential antecedents of positive and negative motivation

Dopamine receptor genes are associated with age at first sexual intercourse

The dopaminergic system in the brain seems to play an important role in the regulation of sexual behaviour. The relationship between genes for the D1, D2 and D4 dopamine receptors and age at first sexual intercourse (AFSI) was examined in a sample of 414 non-Hispanic, European-American men and women. A significant association was observed between a DRD2 allele and AFSI and an even stronger association when the DRD2 allele was interacted with a DRD1 allele. A constrained regression model was constructed predicting AFSI using sex and a group of nine psychosocial variables as predictors. Adding the DRD2 and the DRD2-by-DRD1 predictors to this model increased the explained variance by 23 and 55%, respectively. Although these findings suggest a stronger association among males than among females, further research will be necessary to clarify this question, as well as to establish whether the observed association holds in other racial/ethnic groups.

Childbearing motivation and its measurement.

This paper conceptualises the motive force behind human childbearing as originating in two broad traits which have biological bases, are shaped by experiences during early life and are expressed through their effect on desires and intentions. An instrument for measuring childbearing motivation, the Childbearing Questionnaire (CBQ), is presented. Using a sample of 401 married couples two main scales, nine subscales, and several independent items are described. Evidence for the reliability and validity of this instrument is presented. The versatility of the CBQ as a research instrument and the usefulness of the conceptualisation from which it is derived as a way of integrating social, behavioural, and biological science approaches to childbearing motivation are discussed.

Genetic Influence Helps Explain Variation in Human Fertility: Evidence From Recent Behavioral and Molecular Genetic Studies

To search for genetic influence on human fertility differentials appears inconsistent with past empirical research and prior interpretations of Fishers fundamental theorem of natural selection. We discuss Fishers theorem and give reasons why genetic influences may indeed account for individual differences in human fertility. We review recent empirical studies showing genetic influence on variance in fertility outcomes and precursors to fertility. Further, some of the genetic variance underlying fertility outcomes overlaps with that underlying fertility precursors. Findings from different cultures, different times, different levels of data, and both behavioral and molecular genetic designs lead to the same conclusion: Fertility differentials are genetically influenced, and at least part of the influence derives from behavioral precursors that are under volitional control, which are themselves genetically mediated.

Proception: An important fertility behavior

Social and behavioral scientists have constructed a number of distinct models of fertility and its antecedents. Davis and Blake (1956) originally identified a set of 11 variables that they described as intermediate between a societys culture and social structure, on the one hand, and its fertility, on the other. They included three union variables, three sexual intercourse variables, three conception variables, and two gestation variables. Although these intermediate variables subsequently underwent some modification and redefinition (Bongaarts 1978, 1982), they continue to provide an important basis for theorizing and model building on the part of sociologists and demographers. Economists have also developed models of the antecedents of fertility. For example, the formulation of Easterlin (1978) postulates that fertility depends on both the relative demand for children and fertility regulation. The former is a balance between the households demand for children, called desired family size, and the potential supply of children, the number of surviving children the household would have if it did not regulate fertility. Fertility regulation is the limitation of fertility through the practice of abstinence, contraception, and abortion. Psychologists have contributed a variety of formulations, many being variations on the notion of subjective expected utility (Adler 1979). For example, Jaccard and Davidson (1976), building on the theoretical work of Fishbein (1972), proposed that fertility was a function of fertility intentions, which were a function of an attitudinal factor and a normative factor. Beckman et al. (1983) elaborated a psychological-level model that specifically includes both husband and wife variables. They postulated that fertility is determined by contraceptive use, which is determined by husbands intentions, wifes intentions, and their joint decision. Recently an interdisciplinary panel of the National Academy of Sciences proposed an analytic framework for studying the determinants of fertility in developing countries (Bulatao and Lee 1983). It incorporates biological, psychological, economic, and social factors in an effort to promote understanding at the individual, household, community, societal, and cultural levels. It draws heavily on each of the types of models already mentioned, fitting them into a single, comprehensive, yet flexible framework. What is missing in all of these formulations is a full analysis of the different types of individual behavior that lead directly to conception. In particular, none of these formulations discusses or considers what in many post-fertility-transition nations may be the most important determinant of conception, namely the attempt to achieve conception, what I have called proception (Miller 1973, 1980; Miller and Godwin 1977). This article is devoted to a discussion of the concept of proception and the presentation of some empirical findings regarding patterns of proceptive behavior among married women, the relative importance of proception for marital conceptions, and the psychological antecedents of marital proception.

The effects of ambivalent fertility desires on pregnancy risk in young women in the USA

Many different definitions of the construct of motivational ambivalence have appeared in the literature on reproductive health. Using a theoretical framework in which motivational ambivalence is defined as an interaction between positive and negative pregnancy desires, we propose two hypotheses. The first is that positive and negative pregnancy desires independently predict the risk of an unplanned pregnancy. The second is that ambivalence and three related constructs that are also based on the interaction between positive and negative desires are each important predictors of pregnancy risk. We use weekly journal data collected from a US sample of 1,003 women aged 18–19 years and conduct hazard model analysis to test our hypotheses. Using both dummy and continuous predictors, we report results that confirm both hypotheses. The proposed interaction framework has demonstrated validity, compares favourably with previously reported alternative approaches, and incorporates a set of constructs that have potential importance for further research directed at the prevention of unplanned pregnancy.

Tubal sterilization or vasectomy: how do married couples make the choice?

OBJECTIVE To examine the relative importance of husband, wife, and couple factors as determinants of sterilization method choice. DESIGN Married couples seeking sterilization interviewed before surgery and again 1 year later. SETTING Kaiser Permanente Medical Care Program subscribers seeking care at the Kaiser Foundation Hospital, Santa Clara, California. PARTICIPANTS Two hundred married women seeking a tubal sterilization and their husbands and 200 married men seeking a vasectomy and their wives. INTERVENTIONS None. MAIN OUTCOME MEASURES Sterilization method chosen. RESULTS In a logistic regression model, nine predictor variables correctly classified 94.9% of 395 couples (P less than 0.000). CONCLUSIONS The choice of a sterilization method is achieved primarily through processes that involve both spouses. The motivations of both husband and wife, their mutual influence and communication, their present pattern of contraceptive use, and what they know about the satisfactions or dissatisfactions of other people who have had sterilizations are all factors that should be taken into account when the clinician helps a patient make the method-choice decision.

The pre- and poststerilization predictors of poststerilization regret in husbands and wives.

Husbands and wives from 141 tubal sterilization couples and 162 vasectomy couples were interviewed just prior to sterilization and then again 1 and 2 years later. We conducted linear regression analyses to determine the pre- and poststerilization predictors of poststerilization regret in each of the four gender x method groups (tubal husbands, tubal wives, vasectomy husbands, vasectomy wives). We confirmed a number of hypotheses based on the research literature and our own earlier work. Both individual and couple factors contributed to the development of regret, as did both pre- and poststerilization factors. An important finding was the degree to which regret among the nonsterilized respondents (tubal husbands, vasectomy wives) was affected by pre- and poststerilization interaction with their spouses.