Psychopathic personality in children: genetic and environmental contributions.

BACKGROUND: The current study investigates whether the underlying factor structure of psychopathic personality traits found in adults is similar to that in children and what the extent of the genetic and environmental influences are on these psychopathic traits. METHOD: Psychopathic personality traits were assessed in a community sample of 1219 twins and triplets (age 9-10 years) through caregiver reports of each child's behavior using the Child Psychopathy Scale (CPS). RESULTS: Confirmatory factor analyses revealed an optimal two-factor solution (callous/disinhibited and manipulative/deceitful) to the CPS subscales. Bivariate genetic modeling of the two computed factor scores revealed significant genetic as well as unique environmental influences on psychopathic personality traits in both boys and girls, with heritability estimates of 0.64 and 0.46, respectively, in boys and 0.49 and 0.58, respectively, in girls. No shared environmental influences on psychopathic personality traits were found. CONCLUSIONS: The relationship between the two factors was mediated by both genetic and unique environmental factors common to both traits.

Health and environmental testing of manganese exhaust products from use of methylcyclopentadienyl manganese tricarbonyl in gasoline.

This paper reviews recent research on the environmental effects of methylcyclopentadienyl manganese tricarbonyl (MMT), personal exposures to airborne Mn as a result of MMT use, chemical characterization of the manganese particulates emitted from the tailpipe and progress in developing a (PBPK) model for manganese in rodents. Recent studies show that manganese is emitted as a mixture of compounds with an average valence of about 2.2. The major products are sulfate, phosphate, and smaller amounts of oxides. Because only small amounts of Mn are used in gasoline (<18 mg Mn/gal) and less than 15% of the combusted Mn is emitted, soil along busy roads is not elevated in Mn, even after long-term use of MMT. A very large population-based study of manganese exposures in the general population in Toronto, where MMT has been used continuously for over 20 years, showed that manganese exposures were quite low, the median annual exposure was 0.008 microg Mn/m(3). A great amount of toxicological research on Mn has been carried out during the past few years that provides data for use in developing a PBPK model in rodents. These data add greatly to the existing body of knowledge regarding the relationship between Mn exposure and tissue disposition. When complete, the PBPK model will contribute to our better understanding of the essential neurotoxic dynamics of Mn.

Is thought-action fusion specific to obsessive-compulsive disorder?: a mediating role of negative affect.

Thought-action fusion (TAF) is a cognitive bias presumed to underlie the development of obsessional problems (i.e. obsessive-compulsive disorder; OCD). Previous studies have found that TAF is related to not only OCD, but also to other anxiety disorders. In the present study we compared levels of TAF in OCD patients and in patients with other anxiety disorders, depression, and healthy controls to examine whether TAF is characteristic of individuals with emotional distress in general, as opposed to anxiety disorders per se. We also examined whether negative affect (i.e. anxiety and depression) mediates the relationship between OCD and TAF. Results indicated that OCD patients were characterized by higher scores on likelihood-self and likelihood-other TAF, but that this difference was predominately due to differences in negative affect. These findings support a model in which negative affect mediates the relationship between OCD and TAF.

Using the five-factor model to represent the DSM-IV personality disorders: an expert consensus approach.

This study sought to extend previous work on the five-factor dimensional model (FFM) of personality disorder (PD) by developing more comprehensive FFM descriptions of prototypic cases. Specifically, the authors asked experts in each of the 10 DSM-IV PDs to rate the prototypic case by using all 30 facets of the FFM. Aggregating across raters of the given disorder generated a prototype for each disorder. In general, there was good agreement among experts and with previous theoretical and empirical FFM translations of DSM diagnostic criteria. Furthermore, the ability of the FFM explanation to reproduce the high comorbidity rates among PDs was demonstrated. The authors concluded that, with the possible exception of schizotypal PD, the DSM PDs can be understood from the dimensional perspective of the FFM. Future directions for research, including the use of the present prototypes to "diagnose" personality disorder, are discussed.

Personality disorders as extreme variants of common personality dimensions: can the Five-Factor Model adequately represent psychopathy?

The present study examined Widiger and Lynam's (1998) hypothesis that psychopathy can be represented using the Five-Factor Model (FFM) of personality. Participants in the study consisted of 481 21-22-year-old men and women who are part of an ongoing longitudinal study. Psychopathy was assessed by the degree of similarity between an individual's NEO-PI-R and an expert-generated FFM psychopathy prototype. The expert-based prototype supported the account of Widiger and Lynam (1998), as did the correlations between the NEO-PI-R Psychopathy Resemblance Index (PRI) and the individual personality dimensions. The PRI was also related in predicted ways to measures of antisocial behavior, drug use, and psychopathology. The results support the contention that psychopathy can be understood as an extreme variant of common dimensions of personality, and underscore the utility of a dimensional model of personality disorders.

The association of testosterone with nicotine use in young adult females.

This pilot laboratory study examined the relationship of testosterone levels, carbon monoxide (CO) levels, current and adolescent nicotine use, and histories of pubertal onset in 30 young adult female smokers. These females had completed questionnaires regarding nicotine use in the 7th through 10th grades, and again at age 21 as part of a cohort study of drug use. In addition, history of pubertal onset was obtained at age 21, as were testosterone and CO levels. Testosterone levels were positively correlated with cigarette use in the last 30 days (P< or =.01), CO levels (P< or =.05), cigarette use reported in the 7th and 10th grades (P< or =.05), and negatively correlated with age of pubertal onset (P< or =.001). The relationship of testosterone to nicotine will be discussed.

Particulate matter and manganese exposures in Indianapolis, Indiana.

The distribution of PM(2.5) and manganese (Mn) personal exposures was determined over a 4-month period in Indianapolis, IN, at a time when the gasoline additive, methylcyclopentadienyl manganese tricarbonyl (MMT), was not being used. The data collection period coincided with the data collection period in the Toronto, ON, study, where MMT had been used as a gasoline additive for over 20 years. The inferential or target population consisted of noninstitutionalized residents of the Indianapolis area during the monitoring period (from May 1996 through August 1996) who were at least 16 years old. The survey instruments used in this study (and also in Toronto) included a household screener form (HSF), a study questionnaire (SQ), and a time and activity questionnaire (TAQ). The SQ was administered to elicit information about the participant and his/her activities, occupation, and surroundings that might be relevant to his/her exposure to particles and Mn. In addition to the personal particulate matter (PM) and elemental 3-day monitoring, 240 participants completed a TAQ on a daily basis during the actual monitoring period. Also, a subset of participants had 3-day outdoor and indoor stationary monitoring at their home (approximately 58 observations), and sampling was conducted at a fixed site (approximately thirty-three 3-day observations). The quality of data was assessed and compared to the Toronto study in terms of linearity of measurement, instrument and method sensitivity, measurement biases, and measurement reproducibility. Twenty-six of the sample filters were subjected to two analyses to characterize the within-laboratory component of precision in terms of relative standard deviations (RSDs). The median RSD for Mn was 8.7%, as compared to 2.2% for Toronto. The quality assurance (QA) laboratory exhibited a clear positive bias relative to the primary laboratory for Al and Ca, but no systematic difference was evident for Mn. A high interlaboratory correlation (>0.99) was also attained for Mn. Mean field blank results for PM and Mn were 0.87 microg/m(3) and 0.71 ng/m(3), respectively, which were comparable to the Toronto study. The median RSDs for colocated fixed site and residential samples ranged from 2.2% to 9.0% for PM and from 8.8% to 15.3% for Mn, which were close to those observed in Toronto. For the PM(10), the 90th percentile indoors was 124 microg/m(3) compared with 54 microg/m(3) outdoors. This pattern was even more pronounced for the PM(2.5) data (90th percentiles of 92 microg/m(3) indoors vs 30 microg/m(3) outdoors). Personal PM(2.5) was somewhat higher than the indoor levels, but the percentiles seemed to follow the more highly skewed pattern of the indoor distribution. This difference was largely due to the presence of some smokers in the sample; e.g., exclusion of smokers led to a personal exposure distribution that was more similar to the outdoor distribution. The estimated 90th percentile for the nonsmokers' personal exposures to PM was 43 microg/m(3) compared with 84 microg/m(3) for the overall population. In general, the Indianapolis PM levels of a given type and cut size were somewhat higher than the levels observed in Toronto, e.g., the median and 90th percentile for the personal PM(2.5) exposures were 23 and 85 microg/m(3), respectively, in Indianapolis, while in Toronto, the corresponding percentiles were 19 and 63 microg/m(3). The cities' distributions of the proportion of the PM(10) mass in the 2.5-microm fraction appeared similar for the residential outdoor data (medians of 0.67 and 0.65 for Indianapolis and Toronto, respectively, and 90th percentiles of 0.83 for both cities). For the indoor data, Indianapolis tended to have a larger portion of the mass in the fine fraction (median of 0.80 compared to 0.70 for Toronto). Unlike the PM, the Indianapolis indoor Mn concentration levels were substantially lower than the outdoor levels for both PM sizes, and the median personal levels for Mn in PM(2.5) appeared to fall between the median indoor and outdoor levels. The personal Mn exposure distributions exhibited more skewness than the indoor or outdoor distributions (e.g., the means for the personal, indoor, and outdoor distributions were 7.5, 2.6, and 3.5 ng/m(3), respectively, while the medians were 2.8, 2.2, and 3.2 ng/m(3), respectively). At least a substantial portion of the high end of the personal exposure distribution appeared to be associated with occupational exposures to Mn. In general, the Mn levels in both cut sizes in Indianapolis were approximately 5 ng/m(3) smaller than those in Toronto (e.g., the estimated median and mean levels for personal Mn exposures in PM(2.5) were 2.8 and 7.5 ng/m(3), respectively, in Indianapolis, but were 8.0 and 13.1 ng/m(3) in Toronto). For the nonoccupational subgroups with no exposure to smoking and no subway riders in the two cities, the medians (2.6 ng/m(3) in Indianapolis and 7.8 ng/m(3) in Toronto) were similar to those for the overall populations, but the means were substantially smaller (3.1 ng/m(3) in Indianapolis and 9.2 ng/m(3) in Toronto). The median proportion of Mn in the fine fraction (relative to the PM(10) Mn) for Indianapolis was 0.39 for outdoors and 0.55 for indoors; these ratios were somewhat smaller than the corresponding Toronto medians (0.52 and 0.73). The study found high correlations for particulates and Mn between personal exposures and indoor concentrations, and between outdoor and fixed site concentrations, and low correlations of personal and indoor levels with outdoor and fixed site levels. The pattern was similar to that observed for Toronto, but slightly more pronounced. The PM(10) Mn concentrations (log scale) generally exhibited stronger associations among these various measures than the PM(2.5) Mn concentrations. Comparisons of the particulate distributions between PTEAM (Riverside, CA) and the Indianapolis and Toronto studies were also made.

Male mental health problems, psychopathy, and personality traits: key findings from the first 14 years of the Pittsburgh Youth Study.

This paper reviews key findings on juvenile mental health problems in boys, psychopathy, and personality traits, obtained in the first 14 years of studies using data from the Pittsburgh Youth Study. This is a study of 3 samples, each of about 500 boys initially randomly drawn from boys in the 1st, 4th, and 7th grades of public schools in Pittsburgh. The boys have been followed regularly, initially each half year, and later at yearly intervals. Currently, the oldest boys are about 25 years old, whereas the youngest boys are about 19. Findings are presented on the prevalence and interrelation of disruptive behaviors, ADHD, and depressed mood. Results concerning risk factors for these outcomes are reviewed. Psychological factors such as psychopathy, impulsivity, and personality are described. The paper closes with findings on service delivery of boys with mental health problems.

Differences in young adult psychopathology among drug abstainers, experimenters, and frequent users.

Shedler and Block offered the provocative proposal that individuals who experiment with drugs are psychologically healthier than either those who abstain completely or those who are frequent users. Not all studies have come to such conclusions, however. In an effort to specify under what conditions Shedler and Block's conclusions might hold, the present study examined three groups of drug users (abstainers, experimenters, frequent users) classified according to three different criteria: (a) marijuana use at age 20; (b) alcohol use during 10th grade; and (c) alcohol use at age 20. The three groups were compared at age 20 in terms of personality, deviant behavior, and psychopathology. The results revealed that abstainers were never more psychologically impaired, and were occasionally healthier, than experimenters. Frequent users of marijuana were consistently more imparied than both the abstainers and experimenters, in terms of both internalizing and externalizing disorders. Classification according to marijuana use appeared to be more related to psychopathology than did classification according to alcohol use.

The interaction between impulsivity and neighborhood context on offending: the effects of impulsivity are stronger in poorer neighborhoods.

This research blends 2 traditions of theorizing on the causes of crime, one focused on the role of individual differences and the other focused on structural and contextual variables. Two related studies examined the relations among impulsivity, neighborhood context, and juvenile offending. The first, cross-sectional study uses a large sample of 13-year-old inner-city boys, whereas the second, longitudinal study offers a conceptual replication using 17-year-old inner-city boys who are a subset of the original sample. Across both studies, results indicate that the effects of impulsivity on juvenile offending are stronger in poorer neighborhoods. Furthermore, nonimpulsive boys in poor neighborhoods were at no greater risk for delinquency than nonimpulsive boys in better-off neighborhoods.

Personal exposures to airborne metals in London taxi drivers and office workers in 1995 and 1996.

In 1995, a petroleum marketer introduced a diesel fuel additive in the UK containing Mn as MMT (methylcyclopentadienyl manganese tricarbonyl). A small study of personal exposures to airborne Mn in London was conducted before and after introduction of the additive to identify any major impact of the additive on exposures. In 1995, personal exposures to Mn were measured in two groups, taxi drivers and office workers (10 subjects per group) for two consecutive 7-day periods. A similar study was carried out in 1996 to determine if exposures had changed. Samples were also analyzed for Ca, Al, Mg and Pb. In 1996, exposures to aerosol mass as total suspended particulates (TSP) and PM2.5 were measured in addition to the metals. Manganese exposures in this cohort did not increase as a result of introduction of the additive. However, a significant source of Mn exposure was discovered during the conduct of these tests. The mean exposure to Mn was higher among the office workers in both years than that of the taxi drivers. This was due to the fact that approximately half of the office workers commuted via the underground railway system where airborne dust and metal concentrations are significantly elevated over those in the general environment. Similar results have been noted in other cities having underground rail systems. Exposure to Mn, Pb, Ca, and Mg were not significantly different between the 2 years. Taxi drivers had higher exposures than office workers to Mg and Pb in both years. Commuting via the underground also had a significant impact on exposures to TSP, PM2.5, Al, and Ca, but had little effect on exposures to Mg. The aerosol in the underground was particularly enriched in Mn, approximately 10-fold, when compared to the aerosol in the general environment. There are several possible sources for this Mn, including mechanical wear of the steel wheels on the steel rais, vaporization of metal from sparking of the third rail, or brake wear.

Self-reported psychopathy: a validation study.

Two studies are reported examining the reliability and validity of Levenson's Self-Report Psychopathy Scale (LSRP; Levenson, Kiehl, & Fitzpatrick, 1995) in a noninstitutionalized population. The first study used 1,958 undergraduates to examine the factor structure of the LSRP and its relation to serious antisocial behavior and common dimensions of personality. The second study (n = 70) included performance tasks known to discriminate psychopathic from nonpsychopathic prisoners. Results of the studies support the reliability and validity of the LSRP. The 2-factor structure of the inventory was strongly replicated in a series of confirmatory factor analyses. Predicted relations were observed between the LSRP and other self-report instruments of delinquency. In addition, the factors of the LSRP demonstrated the predicted divergent relations to traditional personality traits. Finally, psychopathic undergraduates showed deficits in response modulation similar to those observed in incarcerated psychopaths. Implications for psychopathy in general are also discussed.

Project DARE: no effects at 10-year follow-up.

The present study examined the impact of Project DARE (Drug Abuse Resistance Education), a widespread drug-prevention program, 10 years after administration. A total of 1,002 individuals who in 6th grade had either received DARE or a standard drug-education curriculum, were reevaluated at age 20. Few differences were found between the 2 groups in terms of actual drug use, drug attitudes, or self-esteem, and in no case did the DARE group have a more successful outcome than the comparison group. Possible reasons why DARE remains so popular, despite the lack of documented efficacy, are offered.

Environmental effects and exposures to manganese from use of methylcyclopentadienyl manganese tricarbonyl (MMT) in gasoline.

Methylcyclopentadienyl Manganese Tricarbonyl (MMT) has been used since the 1970s in the U.S. as a gasoline octane enhancer Extensive testing of the effects of MMT on regulated gaseous emissions carried out on a wide variety of automobiles showed that use of MMT resulted in significantly lower NOx emissions Tests showed that less than 15% of the manganese from MMT combustion was emitted from the tailpipe, mostly in the PM2.5 fraction as manganese phosphate, with some manganese sulfate and a very small amount of manganese oxide. MMT has been used in Canada in virtually all unleaded gasoline for about 20 years. A probability-based study involving over 900 personal exposure samples in Toronto confirmed exposures to airborne PM2.5 Mn in the general population are quite low (.008 microgram/m3-median). Ambient levels of airborne manganese in Toronto are about the same as those in areas where MMT is not used. Exposures to manganese among the general population in Toronto are well within safe limits determined by the U.S. EPA and other standard setting bodies around the world.

Risky sex behavior and substance use among young adults.

Many young adults, despite widespread prevention and education efforts that target this age group, engage in behaviors that place them at risk of HIV infection. These behaviors include frequent experimentation with alcohol and other drugs before sex, sexual activity with different partners, and inconsistent safe-sex practices. The combination of these risky behaviors causes increased concern about the spread of HIV among this age group. The study discussed in this article examined the relationship between substance use during adolescence and HIV risk behavior among young adults ages 19 to 21 with and without a college education. Results indicated that increased use of alcohol and marijuana at younger ages is related to riskier sexual activity and increased use of alcohol and marijuana as young adults. Recommendations for interventions are made.

PIP: A mailed survey was conducted to assess the risky sexual behavior and substance abuse among an initial sample of 2071 young adults in Lexington, Kentucky, during the 1987-88 school year. The survey included specific items about peer relations, family attachment, self-esteem, sensation seeking, friends' drug use, impulsivity, physical health, health and mental health utilization, dieting, delinquency, violence, and risky sexual behavior. A total of 952 (400 males and 552 females) respondents were included in the final analysis. The findings indicate that earlier initiation of sexual activity is related to early involvement with drugs. Furthermore, male participants who used alcohol or marijuana at a younger age engaged in riskier sexual behavior than female participants. Female participants were more likely to use condoms regardless of their early substance use patterns; and those who had never experienced sex or who initiated sex later (ages 19 or 20) were less likely to report lifetime or current drug use. This study indicated that there is a relationship between the early occurrence of substance use and riskier sexual behavior. Recognizing the use of alcohol or marijuana during adolescence may raise practitioners' awareness, helping them identify HIV risk behavior among young adults more accurately.

Early identification of the fledgling psychopath: locating the psychopathic child in the current nomenclature.

This research attempted to test D. R. Lynam's (1996) hypothesis regarding the developmental relation between adult psychopathy and children with symptoms of hyperactivity, impulsivity, and attention problems (HIA) and concurrent conduct problems (CP). In a large sample of adolescent boys, 4 groups (non-HIA-CP, HIA only, CP only, and HIA-CP) were compared on measures found to discriminate between psychopathic and nonpsychopathic offenders. In line with predictions, the HIA-CP boys most closely resembled psychopathic adults. HIA-CP boys scored higher than HIA-only and non-HIA-CP boys on a measure of psychopathic personality. As with their adult counterparts, HIA-CP boys were the most antisocial, were the most disinhibited, and tended to be the most neuropsychologically impaired of all the groups. Implications for treatment, research, and the study of comorbidity are discussed.

Pursuing the psychopath: capturing the fledgling psychopath in a nomological net.

The present article reports on an attempt to import the concept of psychopathy at the childhood level. Childhood psychopathy was assessed in 430 boys ages 12 and 13 years by using caretaker reports on a translation of an adult psychopathy assessment instrument. A systematic construct validation approach revealed that childhood psychopathy fits into the nomological network surrounding adult psychopathy. Children with psychopathic personalities, like their adult counterparts, were serious and stable offenders, impulsive, and more prone to externalizing than internalizing disorders. Childhood psychopathy also provided incremental validity in predicting serious stable antisocial behavior in adolescence over and above other known predictors and one other classification approach. These results suggest that psychopathy has a childhood manifestation that can be measured reliably. Implications and future directions are outlined.

Personal exposure to elements in Mexico City air.

Personal exposures to various metals in airborne particulates in Mexico City were measured over a seven consecutive-day period. Subjects were divided into two groups, Group A, whose work required them to spend considerable time outdoors and in traffic (messengers, delivery men, taxi drivers, salesmen), and Group B who spent most of their time indoors (university professors, consultants, managers and research workers). Group A spent 32 +/- 8.5% of their time outdoors, while Group B spent 10.7 +/- 6.7% of their time outdoors. Group A had higher exposures to airborne lead, zinc, vanadium, manganese and chromium than did Group B. There was no difference between the groups with respect to airborne copper exposures. Overall exposures to the various airborne metals were: lead, 435 +/- 220 ng m-3; zinc, 361 +/- 253 ng m-3; vanadium, 23 +/- 12 ng m-3; manganese, < or = 30 +/- 25 ng m-3; chromium, < or = 8.5 +/- 5.5 ng m-3; and copper, < or = 45 +/- 32 ng m-3. A significant number of samples were below the analytical limits of detection for manganese and copper.

Explaining the relation between IQ and delinquency: class, race, test motivation, school failure, or self-control?

An inverse relation between IQ and delinquency has been well established, but the direction of effect remains to be specified. Differing explanatory accounts of the relation were empirically examined in the present study using data on 13-year-old boys involved in a high-risk longitudinal study. Accounts that interpreted the relation as spurious or that posited that delinquency-related factors lead to low IQ scores received no support; findings were most consistent with the hypothesis that the direction of effect runs from low IQ to delinquency. The IQ-delinquency relation was robust after race, class, and observed test motivation were controlled statistically. Additionally, the effect of IQ was mediated by school performance for Black youth but not for White youth.