A Longitudinal Analysis of Gene x Environment Interaction on Verbal Intelligence Across Adolescence and Early Adulthood

The Scarr-Rowe hypothesis proposes that the heritability of intelligence is higher in more advantaged socioeconomic contexts. An early demonstration of this hypothesis was Rowe and colleagues (Rowe et al., Child Dev 70:1151-1162, 1999), where an interaction between the heritability of verbal intelligence and parental education was identified in adolescent siblings in Wave I of the National Longitudinal Study of Adolescent to Adult Health. The present study repeated their original analysis at Wave I using contemporary methods, replicated the finding during young adulthood at Wave III, and analyzed the interaction longitudinally utilizing multiple measurements. We examined parental education, family income, and peer academic environment as potential moderators. Results indicated increased heritability and decreased shared environmental variance of verbal intelligence at higher levels of parental education and peer academic environment in adolescence. Moreover, moderation by peer academic environment persisted into adulthood with its effect partially attributable to novel gene-environment interactions that arose in the process of cognitive development.

A Secondary Traumatic Stress Reduction Program in Emergency Room Nurses

Introduction

Secondary traumatic stress is highly prevalent among nurses, especially among nurses working within the emergency department (ED). Reducing healthcare worker secondary traumatic stress is important for ensuring the delivery of high quality, safe patient care. This paper reports on the development and implementation of a secondary traumatic stress reduction program.

Methods

We used an adaption of a 5-week intervention based on the Accelerated Recovery Program to test whether there would be a reduction in secondary traumatic stress in a pilot sample of nine ED nurses. Outcomes were assessed using the Secondary Traumatic Stress Scale (STSS), Somatic Symptoms Scale (SSS), and Compassion Satisfaction subscale (CSS) measures.

Results

Eight of nine nurses were able to complete at least three of the five sessions. Results indicate significant change in STSS (F[5,23]  =  4.22, p  =  .007) and SSS (F[3,15]  =  4.42, p  =  .02) scores, but not CSS (F[5,23]  =  0.83, p  =  .54) scores. Pairwise comparisons revealed that the beneficial effects of the program happened early. For both STSS and SSS, scores at sessions 1 and 2 were generally higher than subsequent sessions. We also found a trend for continued effects on STSS at a four-month follow-up (t₂₃  =  1.95, p  =  .064).

Conclusion

Overall, results indicate the 5-week program was associated with a significant reduction in secondary traumatic stress and related somatic symptoms in healthcare workers.

Race, health, and socioeconomic disparities associated with malingering in psychiatric patients at an urban emergency department

OBJECTIVE

To examine clinical and sociodemographic differences between psychiatric patients suspected of malingering and non-malingering controls in an urban emergency department (ED) setting.

METHODS

We used retrospective chart review to compare 57 psychiatric patients suspected of malingering with 195 date-matched controls. We examined evidence used for malingering and documented secondary gains.

RESULTS

The prevalence of malingering was 5.6-7.1%, with documented evidence consistent with DSM-V guidelines. Malingering patients were more likely to be male (p < .001), > 45 years old (p = .002), Black (p = .049), unhoused (p < .001), and frequent users of ED (p < .001). Psychiatric diagnoses were found in ~75% of malingerers. Diagnosis of antisocial personality (OR = 8.03, p = .013) and substance use disorder (OR = 2.05, p = .018) predicted increased probability of malingering. Malingering encounters were more likely to result in discharges (p < .001). The most common secondary gains were unmet clinical needs.

CONCLUSIONS

Results support adaptational models of malingering. Malingering patients are more likely to have sociodemographic vulnerabilities. A disproportionate number of malingering patients have unmet needs for psychiatric treatment and resources. The study provides further evidence for inequities that may be related to social and structural determinants of health.

Racial and ethnic comparison of ecological risk factors and youth outcomes: A test of the desensitization hypothesis

Minority youth, because of structural, ecological, and societal inequalities, are at heightened risk of reporting depression and experiencing negative sanctions associated with delinquency. Sociological theories suggest that greater exposure to ecological risk factors at the peer, family, school and community levels are associated with elevated rates of youth depression and delinquency. Desensitization theory posits that repeated exposures to ongoing stressors result in a numbing of psychological and behavioral responses. Thus, it remains unclear whether racial/ethnic differences exist with regards to how contextual stressors correlate with depression and delinquency. Using a sample of 616 Black, 687 Latinx, and 1,318 White youth, this study explores racial/ethnic differences across four ecological risk factors of risky peers, low family warmth, poor school engagement, and community violence as they relate to youth delinquency and depression. Data were collected through in-school survey of youth from 16 public schools surrounding a major city in the Midwest. Significant racial/ethnic differences provided partial support for the desensitization theory. Among Black youth, the magnitude of relationships between ecological risk factors and delinquency was significantly weaker for three of the four predictors and for all four predictors of depression in comparison to White youth. Among Latinx youth, the magnitude of relationships between ecological risk factors was significantly weaker for depression, but not delinquency, in comparison to White youth. Results indicate that ecological risk factors may have differential associations to youth depression and delinquency, which may call for culturally tailored intervention approaches.

Posttraumatic stress symptom persistence across 24 years: association with brain structures

Posttraumatic stress disorder (PTSD) is known to persist, eliciting early medical co-morbidity, and accelerated aging. Although PTSD diagnosis has been found to be associated with smaller volume in multiple brain regions, posttraumatic stress (PTS) symptoms and their associations with brain morphometry are rarely assessed over long periods of time. We predicted that persistent PTS symptoms across ~24 years would be inversely associated with hippocampal, amygdala, anterior cingulate volumes, and hippocampal occupancy (HOC = hippocampal volume/[hippocampal volume + inferior lateral ventricle volume]) in late middle age. Exploratory analyses examined prefrontal regions. We assessed PTS symptoms in 247 men at average ages 38 (time 1) and 62 (time 2). All were trauma-exposed prior to time 1. Brain volumes were assessed at time 2 using 3 T structural magnetic resonance imaging. Symptoms were correlated over time (r = 0.46 p < .0001). Higher PTS symptoms averaged over time and symptoms at time 1 were both associated with lower hippocampal, amygdala, rostral middle frontal gyrus (MFG), and medial orbitofrontal cortex (OFC) volumes, and a lower HOC ratio at time 2. Increased PTS symptomatology from time 1 to time 2 was associated with smaller hippocampal volume. Results for hippocampal, rostral MFG and medial OFC remained significant after omitting individuals above the threshold for PTSD diagnosis. Even at sub-diagnostic threshold levels, PTS symptoms were present decades after trauma exposure in parallel with highly correlated structural deficits in brain regions regulating stress responsivity and adaptation.

Association of baseline semantic fluency and progression to mild cognitive impairment in middle-aged men

OBJECTIVE

To test the hypothesis that individual differences in episodic memory and verbal fluency in cognitively normal middle-aged adults will predict progression to amnestic mild cognitive impairment (MCI) after 6 years.

METHOD

The cohort analyzed included 842 male twins who were cognitively normal at baseline (mean 56 years) and completed measures of episodic memory and verbal fluency at baseline and again 6 years later (mean 62 years).

RESULTS

Poor episodic memory predicted progression to both amnestic MCI (odds ratio [OR], 4.42; 95% confidence interval [CI], 2.44-10.60) and nonamnestic MCI (OR, 1.92; 95% CI, 1.32-3.44). Poor semantic verbal fluency also independently predicted progression to amnestic MCI (OR, 1.86; 95% CI, 1.12-3.52). In the full sample, a semantic-specific fluency latent variable at wave 1 (which controls for letter fluency) predicted change in episodic memory at wave 2 (β = 0.13), but not vice versa (β = 0.04). Associations between episodic memory and verbal fluency factors were primarily explained by genetic, rather than environmental, correlations.

CONCLUSIONS

Among individuals who were cognitively normal at wave 1, episodic memory moderately to strongly predicted progression to MCI at average age 62, emphasizing the fact that there is still meaningful variability even among cognitively normal individuals. Episodic memory, which is typically a primary focus for Alzheimer disease (AD) risk, declined earlier and more quickly than fluency. However, semantic fluency at average age 56 predicted 6-year change in memory as well as progression to amnestic MCI even after accounting for baseline memory performance. These findings emphasize the utility of memory and fluency measures in early identification of AD risk.

Genetic Underpinnings of Increased BMI and Its Association With Late Midlife Cognitive Abilities

Objectives: First, we test for differences in various cognitive abilities across trajectories of body mass index (BMI) over the later life course. Second, we examine whether genetic risk factors for unhealthy BMIs—assessed via polygenic risk scores (PRS)—predict cognitive abilities in late-life. Methods: The study used a longitudinal sample of Vietnam veteran males to explore the associations between BMI trajectories, measured across four time points, and later cognitive abilities. The sample of 977 individuals was drawn from the Vietnam Era Twin Study of Aging. Cognitive abilities evaluated included executive function, abstract reasoning, episodic memory, processing speed, verbal fluency, and visual spatial ability. Multilevel linear regression models were used to estimate the associations between BMI trajectories and cognitive abilities. Then, BMI PRS was added to the models to evaluate polygenic associations with cognitive abilities. Results: There were no significant differences in cognitive ability between any of the BMI trajectory groups. There was a significant inverse relationship between BMI-PRS and several cognitive ability measures. Discussion: While no associations emerged for BMI trajectories and cognitive abilities at the phenotypic levels, BMI PRS measures did correlate with key cognitive domains. Our results suggest possible polygenic linkages cutting across key components of the central and peripheral nervous system.

Psychometric properties of the Community Violence-Prevention Activation Measure (CV-PAM): Evaluating provider activation toward community violence prevention

This study reports on the conceptualization of activation, and the development and psychometrics of the Community Violence-Prevention Activation Measure (CV-PAM). The CV-PAM was adapted from the Patient Activation Measure (PAM; Hibbard et al., 2004, Health Serv Res, 39, 1005-1026; Hibbard et al., 2005, Health Serv Res, 40, 1918-1930) for use among a workforce servicing youth exposed to community violence. Activation toward community violence prevention is defined as a process in which community members are activated to prevent violence, believe they have important roles to play in violence prevention and supporting the well-being of community members. Activated community members have a good understanding of the factors that contribute to violence and they apply skills and strategies that are consistent with prevention efforts. Six hundred and ninety-four youth providers completed the 18-item CV-PAM to describe their level of activation toward community violence. Exploratory and confirmatory factor analyses were performed and demonstrated that a three factor versus a four factor structure of activation (modeled after PAM) held together. The three factors included (a) belief that an active role is important to address community violence; (b) having the confidence and knowledge to take action around community violence prevention; (c) taking action: frequency of participation and responsiveness to community needs. The proposed fourth factor, staying the course under stress, did not have any qualifying loadings, and thus, could not be interpreted. CV-PAM performed well in tests of reliability and validity. The CV-PAM appears to be a precise, valid, reliable, and useful measure. Implications suggest that using this tool is potentially the first step toward understanding activation among engaged providers and a stepping stone toward increased involvement in community violence prevention through implementation and dissemination efforts.

Body mass trajectories and cortical thickness in middle-aged men: a 42-year longitudinal study starting in young adulthood

Evidence strongly suggests that being overweight or obese at midlife confers significantly higher risk for Alzheimer's disease and greater brain atrophy later in life. Few studies, however, examine associations between longitudinal changes in adiposity during early adulthood and later brain morphometry. Measures of body mass index (BMI) were collected in 373 men from the Vietnam Era Twin Study of Aging at average ages 20, 40, 56, and 62 years, yielding 2 BMI trajectories. We then examined associations between BMI phenotypes (trajectories, continuous BMI, obese/nonobese), cortical thickness, and white matter measures from structural magnetic resonance imaging at mean age 62 (time 4, range 56-66 years). Those on the obesity trajectory (N = 171) had a thinner cortex compared with the normal/lean trajectory (N = 202) in multiple frontal and temporal lobe bilateral regions of interest: superior, inferior, middle temporal gyri, temporal pole, fusiform gyrus, banks of the superior temporal sulcus, frontal pole, pars triangularis, caudal and rostral middle frontal gyri (all p < 0.05, false discovery rate corrected). Frontal lobe thinness tended to occur mainly in the right hemisphere. Results were similar for obese versus nonobese adults at age 62. There were no significant differences for white matter volume or abnormalities. Taken in the context of other research, these associations between brain structures and excess BMI at midlife suggest potential for increased risk for cognitive decline in later life.

Genetic and Environmental Associations Among Executive Functions, Trait Anxiety, and Depression Symptoms in Middle Age

Multiple executive functions (EFs) are associated with trait anxiety and depression symptoms, but it is unclear how genetic and/or environmental factors account for these associations, and if they are explained by general variance underlying multiple EFs (i.e., Common EF). In this study, 1207 male twins completed seven EF tasks and measures of trait anxiety and depression symptoms at average age 62. The Common EF factor was associated with both anxiety (r= -.25) and depression symptoms (r= -.35). Anxiety and depression had near complete genetic overlap (r g=.96). Genetic influences shared with depression accounted for 83% of the phenotypic correlation between anxiety and Common EF. For depression, the phenotypic correlation with Common EF was explained by genetic influences shared with anxiety (69%), but also nonshared environmental influences distinct from anxiety (20%). These results suggest that genetic influences on Common EF play a role in the observed genetic overlap between anxiety and depression.

Associations Between Pet Ownership and Attitudes Toward Pets With Youth Socioemotional Outcomes

Evidence regarding the effects of pet ownership and related variables on youth socioemotional development is mixed. Inconsistencies across studies may be due to a variety of factors, including the use of different outcomes measured across studies, small potential effect sizes, and use of selected samples. In addition, studies have not systematically controlled for demographic characteristics that may bias results, nor have studies systematically examined whether effects are consistent across different subgroups. The present study examined the impact of pet ownership and attitudes toward pets on four measures of youth socioemotional outcomes: delinquency, depressed mood, empathy, and prosocial behavior. Linear mixed-effect regression analyses were conducted on 342 youth (48.0% male) aged 9-19 (M = 14.05, SD = 1.77) from a racially, ethnically, and socioeconomically diverse sample. The majority (59.1%) of youth currently lived with a dog or cat and all participants completed the Pet Attitude Scale-Modified. Pet owners reported lower delinquency and higher empathy than non-owners; however, group differences became non-significant once demographic factors were controlled for. Attitudes toward pets was significantly associated with all four outcomes. More positive attitudes was modestly associated with lower delinquency (β = -0.22, p < 0.001) and higher empathy (β = 0.31, p < 0.001), with smaller effects for depressed mood (β = -0.12, p = 0.04) and prosocial behavior (β = 0.12, p = 0.02). For delinquency, empathy, and prosocial behavior, effects were only slightly attenuated and remained statistically significant after controlling for gender, age, race/ethnicity, family socioeconomic status, and pet ownership, although the effect for depressed mood became non-significant after inclusion of these demographic factors. While there was some variability in effect sizes across different subgroups, none of the interactions between attitudes toward pets and gender, race/ethnicity, age, family SES, or pet ownership was statistically significant, indicating that the effects may transcend individual differences in demographic characteristics. Overall, the study adds to a growing body of work supporting a positive relationship between emotional bonds with pets and youth socioemotional outcomes and offers potential explanations for inconsistencies across previous studies.

Catatonia Under-Diagnosis in the General Hospital

Catatonia is under-diagnosed in psychiatric settings. No studies have explored the under-diagnosis of catatonia in general hospitals. The authors conducted a retrospective chart review using DSM-5 criteria to diagnose catatonia in medical inpatients between 2011 and 2013. Of 133 case subjects meeting DSM-5 criteria for catatonia retrospectively, 79 had never been diagnosed and 54 had a documented diagnosis. Multiple logistic regression revealed that psychiatry consultation significantly decreased the odds of under-diagnosis of catatonia, whereas presence of agitation, grimacing, or echolalia increased the likelihood of under-diagnosis. Under-diagnosed case subjects received significantly lower doses of lorazepam, and increased mortality during admission and increased length of hospital stay both fell short of statistical significance in this group. Catatonia appears to be frequently under-diagnosed in the general hospital, and psychiatry consultation services play a crucial role in its detection and treatment. Strategies to improve recognition and treatment of catatonia should be implemented.

Underdiagnosis of mild cognitive impairment: A consequence of ignoring practice effects

INTRODUCTION

Longitudinal testing is necessary to accurately measure cognitive change. However, repeated testing is susceptible to practice effects, which may obscure true cognitive decline and delay detection of mild cognitive impairment (MCI).

METHODS

We retested 995 late-middle-aged men in a ∼6-year follow-up of the Vietnam Era Twin Study of Aging. In addition, 170 age-matched replacements were tested for the first time at study wave 2. Group differences were used to calculate practice effects after controlling for attrition effects. MCI diagnoses were generated from practice-adjusted scores.

RESULTS

There were significant practice effects on most cognitive domains. Conversion to MCI doubled after correcting for practice effects, from 4.5% to 9%. Importantly, practice effects were present although there were declines in uncorrected scores.

DISCUSSION

Accounting for practice effects is critical to early detection of MCI. Declines, when lower than expected, can still indicate practice effects. Replacement participants are needed for accurately assessing disease progression.

Stability of genetic and environmental influences on executive functions in midlife

Research on executive functions (EFs) has revealed that individual differences in general EF abilities are highly correlated across the first few decades of life, especially at the level of genetic influences. Our work has also provided evidence for substantial heritability of this Common EF factor in midlife, but it remains unclear whether individual differences in Common EFs continue to show strong stability in middle age. We examined data from 1,464 middle-aged twins from the Vietnam Era Twin Study of Aging, most of whom completed 7 neuropsychological measures of EFs at 2 points in middle age (M_ages = 56 and 62). Confirmatory factor analysis indicated that individual differences in Common EF, a latent factor explaining variation in seven neuropsychological EF tasks, were highly correlated across this 6-year period (r = .97), and that the same genetic and environmental influences were operating across this interval (genetic and shared environmental correlations = 1.0, nonshared environment correlation = .95). Similar phenotypic and genetic stability was observed for a Working Memory (WM)-Specific latent factor, which explained additional variance in working memory span tasks not captured by Common EF (r = .98, genetic correlation = 1.0, nonshared environmental correlation = .88). There was a large mean-level performance decline in Common EF (d = -.60) but not WM-Specific (d = -.03). These results suggest that there is substantial decline in Common EF abilities across middle age but that individual differences are almost perfectly stable. (PsycINFO Database Record

Mediators of the Effect of Childhood Socioeconomic Status on Late Midlife Cognitive Abilities: A Four Decade Longitudinal Study

Background and Objectives

Childhood socioeconomic status (cSES) is found to predict later-life cognitive abilities, yet the mechanisms underlying these associations remain unclear. The objective of this longitudinal study was to examine the direct and indirect paths through which cSES influences late midlife cognitive outcomes.

Research Design and Methods

Participants were 1,009 male twins in the Vietnam Era Twin Study of Aging (VETSA). At mean ages 20 and 62, participants completed a standardized test for general cognitive ability (GCA). The age 62 cognitive assessment also included in-person tests of processing speed, episodic memory, abstract reasoning, working memory, verbal fluency, visual-spatial ability, and executive functions. At mean age 56, participants were interviewed regarding their own and their parents’ education and occupation, and completed questionnaires about cognitive leisure activities and sociodemographic information. Multiple mediation analyses were conducted to examine the direct path effects and indirect path effects of cSES through age 20 GCA, adult SES, and cognitive leisure activities on seven cognitive outcomes at age 62, adjusting for age, ethnicity, and non-independence of observations.

Results

Total (direct plus indirect) effects were significant for all measures with the exception of executive functions. Men from lower cSES backgrounds had poorer cognitive functioning in late midlife. The direct effect of cSES was partially mediated for abstract reasoning, and was fully mediated for the remaining six cognitive outcomes. Total indirect effects accounted for at least half of the total effects in each model, with paths through age 20 GCA explaining most of the total indirect effects.

Discussion and Implications

cSES predicted cognitive functioning in late middle age Using multiple mediation models, we show that lower cSES predicts poorer cognition in late midlife primarily through young adult cognitive ability and to a lesser extent through SES in adulthood and engagement in cognitively stimulating activities.

Reduced frontal grey matter, life history of aggression, and underlying genetic influence

Physically healthy, adult, same-sexed twins (n = 287) from a population-based twin cohort underwent high-resolution magnetic resonance imaging (MRI) to identify fronto-limbic brain regions significantly associated with lifetime history of aggression. MRI scans used a 3D magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequence, for voxel-based morphometry (VBM) and history of aggressive behavior was assessed using the Life History of Aggression measure. Aggression had modest, inverse associations with grey matter volume (GMV) in medial prefrontal cortex (mPFC, b = -0.20, se = 0.05, p < 0.001) and lateral prefrontal cortex (lPFC, b = -0.23, se = 0.06, p < 0.001). These associations were not confounded by other demographic, psychiatric, or personality factors. Biometrical twin analyses revealed significant heritabilities of 0.57 for GMV in the mPFC cluster and 0.36 for GMV in the lPFC cluster. Genetic factors accounted for the majority of the phenotypic correlations between aggression and mPFC GMV (85.3%) and between aggression and lPFC GMV (63.7%). Reduced GMV of prefrontal brain regions may be a neuronal characteristic of individuals with substantial histories of aggressive behavior regardless of psychiatric diagnosis. As such, these data suggest an anatomical correlate, with a possible genetic etiology, associated with functional deficits in social-emotional information processing.

A Web-Based Study of Dog Ownership and Depression Among People Living With HIV

BACKGROUND

People living with human immunodeficiency virus (PLHIV) are approximately twice as likely to be depressed compared with HIV-negative individuals. Depression is consistently associated with low antiretroviral therapy (ART) adherence, an important step within the HIV care continuum related to HIV disease progression and overall health. One factor that may have positive psychosocial benefits and promote ART adherence is dog ownership. Research indicates that dog ownership is associated with lower depression, and initial evidence suggests its positive impact on psychosocial outcomes for PLHIV.

OBJECTIVE

The aim of our study was to expand the existing research by examining the relationship between current dog ownership and depression for a sample of PLHIV while controlling for demographic characteristics and other potential confounders.

METHODS

Participants aged 18 years or older and who self-reported an HIV diagnosis were recruited via social media into When Dogs Heal, a cross-sectional Web-based survey to collect data among adult PLHIV. The research visit was conducted via a Web-based survey, and there was no in-person interaction with the participant. Primary outcome measures included demographic questions (age, race, ethnicity, gender, and sexual orientation), pet ownership (type of pet owned and current dog ownership), depression (Center for Epidemiologic Studies Depression Scale, 10 items), and resilience (Resilience Research Centre Adult Resilience Measure, 28 items).

RESULTS

A total of 252 participants were enrolled into the study in January 2016, with a final analytic sample of 199 participants. Mean age was 49 years, 86.4% (172/199) of participants were male, and 80.4% (160/199) were white. Current dog ownership was prevalent among the sample (68.3%, 136/199). Bivariate analysis indicated that there was no significant relationship between depression and demographic characteristics (age, race, ethnicity, gender, and sexual orientation), with P>.05. The multivariate logistic regression, including age, race, ethnicity, gender, resilience, and current dog ownership, was significant, with P<.001. Of the 6 predictor variables, only 2 were statistically significant: dog ownership and resilience. Noncurrent dog owners had 3 times higher odds of depression in comparison with current dog owners: odds ratio 3.01; 95% CI 1.54-6.21.

CONCLUSIONS

Growing evidence suggests that dog ownership reduces the likelihood of depression and, therefore, may confer long-term health benefits on PLHIV. Future studies should explore whether dog-specific interventions are a feasible and efficacious intervention to improve outcomes among PLHIV.

Genetic and environmental architecture of executive functions in midlife

OBJECTIVE

Research on executive functions (EFs) has revealed evidence for general abilities that underlie performance across multiple EF tasks and domains. This Common EF factor is highly stable in adolescence through young adulthood, correlates with other important cognitive abilities, and is explained largely by genetic influences. However, little is known about Common EF beyond young adulthood. This study examines 3 hypotheses regarding the latent structure, genetic/environmental etiology, and cognitive correlates of Common EF in middle age.

METHOD

We examined data from 1,284 middle-aged twins (51-60 years) in the Vietnam Era Twin Study of Aging who completed 7 neuropsychological measures of EFs, as well as measures of general cognitive ability and processing speed.

RESULTS

Our confirmatory factor analysis indicated that Common EF explained variation across all 7 EF tasks. Inhibition and shifting were subsumed entirely under the Common EF factor, and there was an additional working memory span-specific factor. Common EF was heritable in midlife (a2 = .46), with additional evidence for both shared environmental influences (c2 = .41) and nonshared environmental influences (e2 = .13). Higher Common EF was moderately associated with higher general cognitive ability, measured both in early adulthood and midlife, and faster processing speed in midlife. These correlations were primarily driven by shared genetic influences.

CONCLUSIONS

These results support the hypothesis that Common EF captures similar EF abilities in midlife as in adolescence and young adulthood. However, environmental influences may explain a larger portion of variance in this construct as individuals age. (PsycINFO Database Record

Suspected Delirium Predicts the Thoroughness of Catatonia Evaluation

Although commonly linked to psychiatric disorders, catatonia is frequently identified secondary to neurological and general medical conditions (GMCs). The present study aimed to characterize the diagnostic workup of cases of catatonia in a general hospital setting. The authors performed a retrospective chart review of 54 cases of catatonia, over 3 years. Clinical suspicion of comorbid delirium was the strongest predictor of a more thorough general medical workup. Attribution of catatonia to a psychiatric etiology was associated with significantly less diagnostic workup. Prospective studies should help clarify the relationship between catatonia and delirium and standardize the diagnostic approach to patients presenting with catatonia.

Steeper change in body mass across four decades predicts poorer cardiometabolic outcomes at midlife

OBJECTIVE

This study examined patterns of change in adiposity across four decades starting in young adulthood as well as associations between change and midlife cardiometabolic outcomes.

METHODS

BMI was assessed at ages 20, 40, 56, and 62 years in 977 male veterans from the Vietnam Era Twin Study of Aging. Age 62 (range 56-66) cardiometabolic outcomes included hypertension, diabetes, dyslipidemia, inflammation, and ischemic heart disease. Analyses included latent growth modeling (LGM), latent class growth modeling (LCGM), and logistic regression models.

RESULTS

Linear BMI slope was associated with all outcomes. Accelerated (quadratic) BMI slope was significantly associated with greater risk for hypertension, diabetes, dyslipidemia, and inflammation; odds ratios ranged from 1.93 (diabetes) to 3.15 (dyslipidemia). Initial BMI did not predict later outcomes. Linear slope contributed significant unique variance for diabetes and dyslipidemia even controlling for age 62 BMI. LCGM revealed three trajectories. Men with the relatively stable, lower BMI trajectory had significantly better outcomes than those with trajectories with accelerated increases, especially those including obesity.

CONCLUSIONS

How individuals reach late-midlife BMI is important. Steepness of BMI change across 40 years from young adulthood to late midlife, in addition to late-midlife BMI itself, was robustly associated with greater risk for poor cardiometabolic outcomes.

A longitudinal twin study of general cognitive ability over four decades

In this longitudinal study we examined the stability of general cognitive ability (GCA), as well as heterogeneity and genetic and environmental influences underlying individual differences in change. We investigated GCA from young adulthood through late midlife in 1,288 Vietnam Era Twin Study of Aging participants at ages ∼20, ∼56, and ∼62 years. The correlations among the 3 occasions ranged from .73 to .85, reflecting substantial stability. The heritability was significant on each of the 3 occasions and ranged from .59 to .66. The influence of the shared environment was not significant at any of the ages. The genetic correlations across the 3 occasions ranged from .95 to .99 and did not differ significantly from 1.0. The nonshared environmental correlations ranged from .21 to .47. Latent growth curve analysis was applied to characterize trajectories over the 42-year period. Slope was significantly different from 0 and indicated that there was modest change over time. There was a significant genetic influence on initial level of GCA (h2 = .67), but not change (h2 = .23). Genetic factors primarily contribute to stability, while change reflects the influence of nonshared environmental influences. There was a significant negative correlation between initial level of GCA and change (r = -.31). Latent class growth analysis identified 4 trajectories. In general, the 4 groups followed parallel trajectories and were differentiated mainly by differences in AFQT performance level at the time of military induction. (PsycINFO Database Record

School Context and Genetic Influences on Aggression in Adolescence

Genetic and environmental contributions to variation in aggression were examined using adolescents' self-reports of aggressive behavior. The National Longitudinal Study of Adolescent Health provided a sample of 1,515 pairs of adolescents in five genetically informative groups (i.e., monozygotic twins, dizygotic twins, full siblings, half siblings, and unrelated siblings reared together). The analysis, a DeFries-Fulker regression within a hierarchical linear model, yielded findings on individual-level heritability ( h2), shared environmental effects ( c2), school-level effects, and school-level moderation of h2 and c2. The estimate of h2 for aggression in the full sample was .32, and c2 was .05. In the moderating effect, h2 increased and c2 decreased with greater school-level family warmth. Two effects on school means were found: Those schools with greater ethnic-racial heterogeneity had higher mean levels of aggression, and schools where students perceived greater family warmth had lower mean levels of aggression.

Community Violence Exposure and Adolescent Delinquency: Examining a Spectrum of Promotive Factors

This study examined whether promotive factors (future expectations, family warmth, school attachment, and neighborhood cohesion) moderated relationships between community violence exposure and youth delinquency. Analyses were conducted using N = 2,980 sixth to eighth graders (M _age = 12.48; 41.1% males) from a racially, ethnically, and socioeconomically diverse sample. After controlling for demographic factors, delinquency was positively associated with community violence exposure and inversely associated with each of the promotive factors. When interaction effects between all promotive factors and community violence exposure were examined simultaneously, only future expectations moderated the relationship between community violence exposure and delinquency. Specifically, community violence exposure had a weaker association with delinquency for youth reporting high versus low levels of future expectations. Results indicate that while promotive factors from family, school, and neighborhood domains are related to lower rates of delinquency, only future expectations served as a protective factor that specifically buffered youth from the risk effects of community violence exposure.

A new look at the genetic and environmental coherence of metabolic syndrome components

OBJECTIVE

Metabolic syndrome, a clustering of risk factors including insulin resistance, dyslipidemia, central obesity, and hypertension, increases risk for cardiovascular disease and cognitive decline. The etiology of the risk factors' cohesion remains unclear. How genetic and environmental influences explained co-occurrence of metabolic syndrome components was examined.

METHODS

Continuous measures of body mass index (BMI), waist circumference, blood pressure (BP), fasting insulin and glucose, high-density lipoprotein cholesterol (HDL), and triglycerides from 1,193 middle-aged twin men participating in the Vietnam Era Twin Study of Aging at average age 62 (range 56-67) were analyzed using multivariate biometrical modeling.

RESULTS

Four heritable factors were found: adiposity (BMI, waist circumference), insulin resistance (glucose, insulin), lipids (HDL, triglycerides), and BP (systolic, diastolic). Heritabilities were 0.42-0.68. In the best-fitting model, insulin resistance, lipids, and adiposity comprised a higher-order latent genetic factor. Adiposity and BP shared genetic influences independent of the latent genetic factor. All factors aggregated on a latent unique environmental factor.

CONCLUSIONS

Metabolic syndrome components form the equivalent of two genetic factors. BP was genetically unrelated to insulin resistance and lipids. Adiposity was the only characteristic genetically and environmentally related to all other factors. These results inform strategies for gene discovery and prediction of health outcomes.

Genetic and environmental architecture of changes in episodic memory from middle to late middle age

Episodic memory is a complex construct at both the phenotypic and genetic level. Ample evidence supports age-related cognitive stability and change being accounted for by general and domain-specific factors. We hypothesized that general and specific factors would underlie change even within this single cognitive domain. We examined 6 measures from 3 episodic memory tests in a narrow age cohort at middle and late middle age. The factor structure was invariant across occasions. At both timepoints 2 of 3 test-specific factors (story recall, design recall) had significant genetic influences independent of the general memory factor. Phenotypic stability was moderate to high, and primarily accounted for by genetic influences, except for 1 test-specific factor (list learning). Mean change over time was nonsignificant for 1 test-level factor; 1 declined; 1 improved. The results highlight the phenotypic and genetic complexity of memory and memory change, and shed light on an understudied period of life.

Hippocampal atrophy varies by neuropsychologically defined MCI among men in their 50s

OBJECTIVE

In an effort to address earliest detection of mild cognitive impairment (MCI), we examined hippocampal volumes and atrophy in middle-aged men to explore neuroanatomical support for different neuropsychological definitions of MCI.

METHODS

460 men aged 51-60 years underwent neuropsychological testing and MRI. MCI was defined according to five criteria sets. MRI-derived hippocampal volume and hippocampal occupancy (HOC) were obtained via FreeSurfer. Statistical analyses were performed using linear mixed models.

RESULTS

Differences in HOC between normal cognitive functioning, amnestic, and non-amnestic MCI were observed using MCI criteria that required one impaired (>1.5 SD) cognitive measure in a given cognitive domain or a cognitive composite score method with a cut-point 2 SD below the mean. Differences in standard hippocampal volume were only found between normal and amnestic presentations and only when using the composite score method.

CONCLUSION

Results provide empirical support for detection of pre-MCI in younger cohorts. Convergence of neuropsychological and neuroanatomical data, particularly HOC (as opposed to standard cross-sectional volume), supports early identification of MCI as defined by some neuropsychological criteria.

Infections by Renibacterium salmoninarum and Nanophyetus salmincola Chapin are associated with reduced growth of juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), in the Northeast Pacific Ocean

We examined 1454 juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), captured in nearshore waters off the coasts of Washington and Oregon (USA) from 1999 to 2004 for infection by Renibacterium salmoninarum, Nanophyetus salmincola Chapin and skin metacercariae. The prevalence and intensities for each of these infections were established for both yearling and subyearling Chinook salmon. Two metrics of salmon growth, weight residuals and plasma levels of insulin-like growth factor-1, were determined for salmon infected with these pathogens/parasites, both individually and in combination, with uninfected fish used for comparison. Yearling Chinook salmon infected with R. salmoninarum had significantly reduced weight residuals. Chinook salmon infected with skin metacercariae alone did not have significantly reduced growth metrics. Dual infections were not associated with significantly more severe effects on the growth metrics than single infections; the number of triple infections was very low and precluded statistical comparison. Overall, these data suggest that infections by these organisms can be associated with reduced juvenile Chinook salmon growth. Because growth in the first year at sea has been linked to survival for some stocks of Chinook salmon, the infections may therefore play a role in regulating these populations in the Northeast Pacific Ocean.

Genetic complexity of episodic memory: a twin approach to studies of aging

Episodic memory change is a central issue in cognitive aging, and understanding that process will require elucidation of its genetic underpinnings. A key limiting factor in genetically informed research on memory has been lack of attention to genetic and phenotypic complexity, as if "memory is memory" and all well-validated assessments are essentially equivalent. Here we applied multivariate twin models to data from late-middle-aged participants in the Vietnam Era Twin Study of Aging to examine the genetic architecture of 6 measures from 3 standard neuropsychological tests: the California Verbal Learning Test-2, and Wechsler Memory Scale-III Logical Memory (LM) and Visual Reproductions (VR). An advantage of the twin method is that it can estimate the extent to which latent genetic influences are shared or independent across different measures before knowing which specific genes are involved. The best-fitting model was a higher order common pathways model with a heritable higher order general episodic memory factor and three test-specific subfactors. More importantly, substantial genetic variance was accounted for by genetic influences that were specific to the latent LM and VR subfactors (28% and 30%, respectively) and independent of the general factor. Such unique genetic influences could partially account for replication failures. Moreover, if different genes influence different memory phenotypes, they could well have different age-related trajectories. This approach represents an important step toward providing critical information for all types of genetically informative studies of aging and memory.

Individual differences in cognitive ability at age 20 predict pulmonary function 35 years later

BACKGROUND

Poor pulmonary function is associated with mortality and age-related diseases, and can affect cognitive performance. However, extant longitudinal studies indicate that early cognitive ability also affects later pulmonary function. Despite the multifaceted nature of pulmonary function, most longitudinal studies were limited to a single index of pulmonary function: forced expiratory volume in 1 s (FEV1). In this study, we examined whether early adult cognitive ability predicted five different indices of pulmonary function in mid-life.

METHODS

Mixed modelling tested the association between young adult general cognitive ability (mean age=20), measured by the Armed Forces Qualification Test (AFQT), and mid-life pulmonary function (mean age=55), in 1019 men from the Vietnam Era Twin Study of Aging. Pulmonary function was indexed by per cent predicted values for forced vital capacity (FVC%p), FEV1%p, maximum forced expiratory flow (FEFmax%p), and maximal voluntary ventilation (MVV%p), and by the ratio of FEV1 to FVC (FEV1/FVC), an index of lung obstruction.

RESULTS

After adjusting for smoking, pulmonary disease, occupation, income and education, age 20 AFQT was significantly (p<0.05) associated with mid-life FVC%p (β=0.10), FEV1%p (β=0.13), FEFmax%p (β=0.13), and MVV%p (β=0.13), but was not significantly associated with FEV1/FVC (β=0.03, p=0.34).

CONCLUSIONS

Early adult cognitive ability is a predictor of multiple indices of aging-related pulmonary function 35 years later, including lung volume, airflow and ventilator capacity. Cognitive deficits associated with impaired aging-related lung function may, thus, be partly pre-existing. However, results also highlight that early life risk factors may be differentially related to different metrics of later-life pulmonary health.

Gene-environment interplay in common complex diseases: forging an integrative model—recommendations from an NIH workshop

Although it is recognized that many common complex diseases are a result of multiple genetic and environmental risk factors, studies of gene-environment interaction remain a challenge and have had limited success to date. Given the current state-of-the-science, NIH sought input on ways to accelerate investigations of gene-environment interplay in health and disease by inviting experts from a variety of disciplines to give advice about the future direction of gene-environment interaction studies. Participants of the NIH Gene-Environment Interplay Workshop agreed that there is a need for continued emphasis on studies of the interplay between genetic and environmental factors in disease and that studies need to be designed around a multifaceted approach to reflect differences in diseases, exposure attributes, and pertinent stages of human development. The participants indicated that both targeted and agnostic approaches have strengths and weaknesses for evaluating main effects of genetic and environmental factors and their interactions. The unique perspectives represented at the workshop allowed the exploration of diverse study designs and analytical strategies, and conveyed the need for an interdisciplinary approach including data sharing, and data harmonization to fully explore gene-environment interactions. Further, participants also emphasized the continued need for high-quality measures of environmental exposures and new genomic technologies in ongoing and new studies.

Community Violence Exposure and Sexual Behaviors in a Nationally Representative Sample of Young Adults: The Effects of Race/Ethnicity and Gender

This study examined whether exposure to community violence was related to sexual risk behaviors in a nationally representative sample of young adults and if there were gender or racial/ethnic differences in these relationships. The analytic sample for this study was drawn from the National Longitudinal Study of Adolescent Health and was composed of 7,726 unmarried, heterosexual African American, Caucasian, and Hispanic/Latino young adults aged 18 to 27 years old. Approximately 12% of participants reported some community violence exposures, with men and African Americans reporting the highest rates of such exposures. Regression analyses controlling for age, gender, parental education, and family structure indicated that exposures to community violence were associated with earlier sexual debut history, a higher number of sexual partners within the previous 12 months, and a higher number of total sexual partners. Additionally, violence exposures had stronger effects for males and weaker effects for African Americans. Primary and secondary sexual risk prevention initiatives would need to consider how patterns of sexual risk behaviors may be related to exposure to community violence and how such relationships may differ based on gender and race/ethnicity. Future research should also seek to illuminate pathways connecting these 2 major public health concerns.

Post-traumatic stress symptoms and adult attachment: a 24-year longitudinal study

OBJECTIVES

Attachment theory has become a key framework for understanding responses to and consequences of trauma across the life course. We predicted that more severe post-traumatic stress (PTS) symptoms at age 37 years would be associated with insecure attachment at age 55 and with worse PTS symptoms 24 years later at age 61, and that age 55 attachment would mediate the influence of earlier PTS symptoms on later symptoms.

DESIGN

Data on PTS self-reported symptoms were available for 975 community-dwelling participants from the longitudinal Vietnam Era Twin Study of Aging at ages 37 and 61 years. At age 55, participants completed the Experiences in Close Relationships Inventory, a measure of adult attachment.

RESULTS

PTS symptoms at ages 37 and 61 correlated (r = 0.43; p <0.0001). Multiple mediation models found significant direct effects of age 37 PTS symptoms on age 61 PTS symptoms (β = 0.26; 95% confidence interval: 0.19-0.33). Anxious and avoidant attachment at age 55 predicted PTS symptoms at age 61 (r = 0.34 and 0.25; ps <0.0001, respectively) and also significantly mediated PTS symptoms over time, showing that insecure attachment increased PTS severity. Participants with higher age 37 PTS symptoms were more likely to have a history of divorce; marital status did not mediate PTS.

CONCLUSIONS

Analyses demonstrate the persistence of PTS symptoms from early midlife into early old age. Mediation analyses revealed that one path through which PTS symptoms persisted was indirect: through their influence on attachment insecurity. This study provides insight into ongoing interconnections between psychological and interpersonal responses to stress.

Growth and condition of juvenile coho salmon Oncorhynchus kisutch relate positively to species richness of trophically transmitted parasites

The aims of this study were first, to test the hypothesis that metrics of fish growth and condition relate positively to parasite species richness (S(R)) in a salmonid host; second, to identify whether S(R) differs as a function of host origin; third, to identify whether acquisition of parasites through marine v. freshwater trophic interactions was related to growth and condition of juvenile salmonids. To evaluate these questions, species diversity of trophically transmitted parasites in juvenile coho salmon Oncorhynchus kisutch collected off the coast of the Oregon and Washington states, U.S.A. in June 2002 and 2004 were analysed. Fish infected with three or more parasite species scored highest in metrics of growth and condition. Fish originating from the Columbia River basin had lower S(R) than those from the Oregon coast, Washington coast and Puget Sound, WA. Parasites obtained through freshwater or marine trophic interactions were equally important in the relationship between S(R) and ocean growth and condition of juvenile O. kisutch salmon.

Imputing observed blood pressure for antihypertensive treatment: impact on population and genetic analyses

BACKGROUND

Elevated blood pressure (BP), a heritable risk factor for many age-related disorders, is commonly investigated in population and genetic studies, but antihypertensive use can confound study results. Routine methods to adjust for antihypertensives may not sufficiently account for newer treatment protocols (i.e., combination or multiple drug therapy) found in contemporary cohorts.

METHODS

We refined an existing method to impute unmedicated BP in individuals on antihypertensives by incorporating new treatment trends. We assessed BP and antihypertensive use in male twins (n = 1,237) from the Vietnam Era Twin Study of Aging: 36% reported antihypertensive use; 52% of those treated were on multiple drugs.

RESULTS

Estimated heritability was 0.43 (95% confidence interval (CI) = 0.20-0.50) and 0.44 (95% CI = 0.22-0.61) for measured systolic BP (SBP) and diastolic BP (DBP), respectively. We imputed BP for antihypertensives by 3 approaches: (i) addition of a fixed value of 10/5mm Hg to measured SBP/DBP; (ii) incremented addition of mm Hg to BP based on number of medications; and (iii) a refined approach adding mm Hg based on antihypertensive drug class and ethnicity. The imputations did not significantly affect estimated heritability of BP. However, use of our most refined imputation method and other methods resulted in significantly increased phenotypic correlations between BP and body mass index, a trait known to be correlated with BP.

CONCLUSIONS

This study highlights the potential usefulness of applying a representative adjustment for medication use, such as by considering drug class, ethnicity, and the combination of drugs when assessing the relationship between BP and risk factors.

Early identification and heritability of mild cognitive impairment

BACKGROUND

Identifying mild cognitive impairment (MCI) in midlife could improve early identification of Alzheimer's disease (AD). Also, AD is highly heritable, but the heritability of MCI has not been established. We estimated prevalence rates, association with premorbid general cognitive ability (GCA) and heritability for different definitions of neuropsychologically defined MCI in adults in their 50s.

METHOD

We examined 1126 twins aged 51-59 years when recruited into the Vietnam Era Twin Study of Aging (VETSA). Six neurocognitive domains were assessed using tests designed to avoid ceiling effects. To differentiate MCI from low overall ability, criteria included adjustment for GCA measured at approximately age 20 years.

RESULTS

As in older adults, prevalence rates varied widely. Among the lower prevalence rates were some definitions of multiple-domain MCI and single-domain amnestic MCI, which may be less likely than other MCI categories to revert to normal on follow-up. Low prevalence rates in middle-aged adults are also more likely to be valid. MCI was also associated with lower premorbid GCA. Heritability estimates for any MCI and amnestic MCI averaged .40-.48.

CONCLUSIONS

By testing multiple cognitive domains and avoiding ceiling effects, MCI can be identified before age 60 years. Premorbid GCA is a risk/protective factor, but deficits after adjusting for early adult GCA suggest additional processes leading to declining trajectories. Heritabilities were comparable to AD, suggesting MCI as an appropriate phenotype for genetic association studies. Full validation will require follow-up assessments (currently under way). Community-based studies are important for this early identification because adults of this age are unlikely to present in clinics.

Genetic and Environmental Influences of General Cognitive Ability: Is g a valid latent construct?

Despite an extensive literature, the "g" construct remains a point of debate. Different models explaining the observed relationships among cognitive tests make distinct assumptions about the role of g in relation to those tests and specific cognitive domains. Surprisingly, these different models and their corresponding assumptions are rarely tested against one another. In addition to the comparison of distinct models, a multivariate application of the twin design offers a unique opportunity to test whether there is support for g as a latent construct with its own genetic and environmental influences, or whether the relationships among cognitive tests are instead driven by independent genetic and environmental factors. Here we tested multiple distinct models of the relationships among cognitive tests utilizing data from the Vietnam Era Twin Study of Aging (VETSA), a study of middle-aged male twins. Results indicated that a hierarchical (higher-order) model with a latent g phenotype, as well as specific cognitive domains, was best supported by the data. The latent g factor was highly heritable (86%), and accounted for most, but not all, of the genetic effects in specific cognitive domains and elementary cognitive tests. By directly testing multiple competing models of the relationships among cognitive tests in a genetically-informative design, we are able to provide stronger support than in prior studies for g being a valid latent construct.

Interaction of APOE genotype and testosterone on episodic memory in middle-aged men

Age-related changes in testosterone are believed to be a key component of the processes that contribute to cognitive aging in men. The APOE-ε4 allele may interact with testosterone and moderate the hormone's association with cognition. The goals of the present study were to examine the degree to which free testosterone is associated with episodic memory in a community-based sample of middle-aged men, and examine the potential interaction between free testosterone and the APOE-ε4 allele. Data were used from 717 participants in the Vietnam Era Twin Study of Aging. Average age was 55.4 years (standard deviation = 2.5). Significant positive associations were observed between free testosterone level and verbal episodic memory, as well as a significant interaction between free testosterone and APOE-ε4 status. In ε4 carriers free testosterone was positively associated with verbal episodic memory performance (story recall), whereas no association was observed in ε4 noncarriers. Results support the hypothesis that APOE-ε4 status increases susceptibility to other risk factors, such as low testosterone, which may ultimately contribute to cognitive decline or dementia.

Impulsivity moderates promotive environmental influences on adolescent delinquency: a comparison across family, school, and neighborhood contexts

The present study examined moderating effects of impulsivity on the relationships between promotive factors from family (family warmth, parental knowledge), school (school connectedness), and neighborhood (neighborhood cohesion) contexts with delinquency using data collected from N = 2,978 sixth to eighth graders from 16 schools surrounding a major city in the Midwestern United States. More than half of the respondents were non-Caucasian (M age  = 12.48; 41.0 % male). Multilevel modeling analyses were conducted to take into account the clustering of the participants within schools. Impulsivity was positively associated with adolescent delinquency. Additionally, family warmth, parental knowledge, and school connectedness, but not neighborhood cohesion, were independently and inversely related to adolescent delinquency. Finally, impulsivity moderated relationships between family warmth and parental knowledge with delinquency but not relationships between school attachment and neighborhood cohesion with delinquency. Specifically, the negative relationship between family warmth and delinquency was significant for adolescents with high levels of, but not for those with below-average levels of, impulsivity. In addition, parental knowledge had a stronger association with decreased levels of delinquency for adolescents reporting higher levels of impulsivity. The moderating effects of impulsivity did not differ for males and females or for minority and non-minority participants. Findings indicate that impulsivity may have greater impact on adolescents' susceptibility to positive family influences than on their susceptibility to promotive factors from school or neighborhood contexts. Implications for future research and practice are discussed.

Genetic and environmental influences of daily and intra-individual variation in testosterone levels in middle-aged men

BACKGROUND

Testosterone regulates numerous physiological processes, and evidence suggests that it plays a critical role in male aging. It has yet to be determined whether the heritability of testosterone varies in accordance with its diurnal rhythm. Similarly, it is unclear whether changes in testosterone level throughout the day are genetically influenced. The aim of the present study was to determine the degree to which genetic and environmental factors contribute to individual differences in testosterone throughout the day in middle-aged men.

METHODS

Saliva-based measures of free testosterone, sampled at multiple time-points both at-home and in-lab, were collected from 783 male twins (193 monozygotic pairs, 196 dizygotic pairs, 5 unpaired twins) as part of the Vietnam Era Twin Study of Aging (VETSA). The average age of participants was 55.9 years (SD=2.6).

RESULTS

Testosterone levels declined substantially over the course of the day, with 32-39% of the change occurring in the first 30min after waking. Heritability estimates for specific time-points ranged from .02 to .39. The heritability of the average at-home and in-lab testosterone values were notably higher (.42 and .47 respectively). Daily rates of change showed some evidence of genetic influence, with heritability estimates ranging from .15 to .29, whereas there were no observable genetic influences on coefficients of variation.

CONCLUSIONS

Genetic influences account for a significant proportion of the variance in average testosterone levels, while environmental factors account for the majority of intra-individual variability. These results highlight the need to explore both genetic and individual-specific environmental factors as determinants of free testosterone levels in aging men.

Longitudinal relationships between college education and patterns of heavy drinking: a comparison between Caucasians and African-Americans

PURPOSE

The current study compared longitudinal relationships between college education and patterns of heavy drinking from early adolescence to adulthood for Caucasians and African-Americans.

METHODS

We analyzed data from 9,988 non-Hispanic Caucasian and African-American participants from all four waves of the National Longitudinal Study of Adolescent Health. Growth curve modeling tested differences in rates of change and levels of heavy drinking from ages 13 to 31 years among non-college youth, college withdrawers, 2-year college graduates, and 4-year college graduates, and compared these differences for Caucasians and African-Americans.

RESULTS

There were significant racial differences in relationships between college education with both changes in and levels of heavy drinking. Rates of change of heavy drinking differed significantly across the college education groups examined for Caucasians but not for African-Americans. In addition, Caucasians who graduated from 4-year colleges showed the highest levels of heavy drinking after age 20 years, although differences among the four groups diminished by the early 30s. In contrast, for African-Americans, graduates from 2- or 4-year colleges did not show higher levels of heavy drinking from ages 20 to 31 years than the non-college group. Instead, African-American participants who withdrew from college without an associate's, bachelor's, or professional degree consistently exhibited the highest levels of heavy drinking from ages 26 to 31 years.

CONCLUSIONS

The relationship between college education and increased levels of heavy drinking in young adulthood is significant for Caucasians but not African-Americans. Conversely, African-Americans are likely to be more adversely affected than are Caucasians by college withdrawal.

Genetic and environmental influences on sleep quality in middle-aged men: a twin study

Poor sleep quality is a risk factor for a number of cognitive and physiological age-related disorders. Identifying factors underlying sleep quality are important in understanding the etiology of these age-related health disorders. We investigated the extent to which genes and the environment contribute to subjective sleep quality in middle-aged male twins using the classical twin design. We used the Pittsburgh Sleep Quality Index to measure sleep quality in 1218 middle-aged twin men from the Vietnam Era Twin Study of Aging (mean age = 55.4 years; range 51-60; 339 monozygotic twin pairs, 257 dizygotic twin pairs, 26 unpaired twins). The mean PSQI global score was 5.6 [SD = 3.6; range 0-20]. Based on univariate twin models, 34% of variability in the global PSQI score was due to additive genetic effects (heritability) and 66% was attributed to individual-specific environmental factors. Common environment did not contribute to the variability. Similarly, the heritability of poor sleep-a dichotomous measure based on the cut-off of global PSQI>5-was 31%, with no contribution of the common environment. Heritability of six of the seven PSQI component scores (subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, and daytime dysfunction) ranged from 0.15 to 0.31, whereas no genetic influences contributed to the use of sleeping medication. Additive genetic influences contribute to approximately one-third of the variability of global subjective sleep quality. Our results in middle-aged men constitute a first step towards examination of the genetic relationship between sleep and other facets of aging.

Shared and distinct genetic influences among different measures of pulmonary function

We examined shared and distinct genetic influences among standard measures of pulmonary functions: ratio of forced expiratory volume at 1 s to forced vital capacity (FEV1/FVC) and percent predicted values for forced expiratory volume at 1 s (FEV1%p), forced expiratory flow (FEFmax%p), and maximal voluntary ventilation (MVV%p) in 978-1,048 middle-aged (mean age = 55 years) male-male twins from the Vietnam Era Twin Study of Aging. A common latent factor (h(2) = 0.30) accounted for the correlations among these measures. This factor accounted for 54-81 % of the heritability of FEV1%p, FEFmax%p and MVV%p, but only explained 16 % of the heritability of FEV1/FVC. The remaining heritability of FEV1/FVC was explained by genetic influences independent of the common factor. Our findings suggest that while a common latent phenotype accounts for the relationships among different pulmonary function measures, the majority of genetic influences underlying FEV1/FVC--an index of pulmonary obstruction--are distinct from those underlying other pulmonary function measures.

Do Dog Behavioral Characteristics Predict the Quality of the Relationship between Dogs and Their Owners?

This paper explores whether dog behavioral characteristics predict the quality of the relationship between dogs and their owners (i.e., owner attachment to dog), and whether relations between dog behavior and owner attachment are moderated by demographic characteristics. In this study, N = 92 children and N = 60 adults from 60 dog-owning families completed questionnaires about their attachment to their pet dog, their level of responsibility for that dog, and their general attitudes toward pets. They also rated their dogs on observable behavioral characteristics. Individuals who held positive attitudes about pets and who provided much of their dog's care reported stronger attachments to their dogs. The strength of owners' attachments to their dogs was associated with dog trainability and separation problems. Relationships between owner attachment and both dog excitability and attention-seeking behavior were further moderated by demographic characteristics: for Caucasians but not for non-Caucasians, dog excitability was negatively associated with owner attachment to dog; and for adults, dog attention-seeking behavior was positively associated with owner attachment, but children tended to be highly attached to their dogs, regardless of their dogs' attention-seeking behaviors. This study demonstrates that certain dog behavioral traits are indeed associated with the strength of owners' attachments to their dogs.

Genetic and Environmental Influences on Individual Differences in Frequency of Play with Pets among Middle-Aged Men: A Behavioral Genetic Analysis

There is growing evidence that pet ownership and human-animal interaction (HAI) have benefits for human physical and psychological well-being. However, there may be pre-existing characteristics related to patterns of pet ownership and interactions with pets that could potentially bias results of research on HAI. The present study uses a behavioral genetic design to estimate the degree to which genetic and environmental factors contribute to individual differences in frequency of play with pets among adult men. Participants were from the ongoing longitudinal Vietnam Era Twin Study of Aging (VETSA), a population-based sample of 1,237 monozygotic (MZ) and dizygotic (DZ) twins aged 51-60 years. Results demonstrate that MZ twins have higher correlations than DZ twins on frequency of pet play, suggesting that genetic factors play a role in individual differences in interactions with pets. Structural equation modeling revealed that, according to the best model, genetic factors accounted for as much as 37% of the variance in pet play, although the majority of variance (63-71%) was due to environmental factors that are unique to each twin. Shared environmental factors, which would include childhood exposure to pets, overall accounted for <10% of the variance in adult frequency of pet play, and were not statistically significant. These results suggest that the effects of childhood exposure to pets on pet ownership and interaction patterns in adulthood may be mediated primarily by genetically-influenced characteristics.

Moderating effects of childhood maltreatment on associations between social information processing and adult aggression

BACKGROUND

Associations between early life maltreatment, social information processing (SIP) and aggression in childhood and adolescence have been widely documented. Few studies have examined the importance of childhood maltreatment independent of SIP in the etiology of adult aggression. Furthermore, moderating effects of childhood maltreatment on the SIP-aggression links have not been explored.

METHOD

Hierarchical, multi-level models were fitted to data from n=2752 twins aged 20-55 years from the PennTwins Cohort. Adult aggression was assessed with the Life History of Aggression questionnaire. Childhood maltreatment was measured using the Childhood Trauma Questionnaire. Two aspects of SIP were examined: hostile attribution biases (HAB); negative emotional responses (NER).

RESULTS

Childhood maltreatment was positively correlated with adult aggression, independently of HAB and NER. In addition, childhood maltreatment moderated the relationships between both aspects of SIP and adult aggression. Specifically, the relationship between NER and aggression was stronger among individuals with higher levels of childhood maltreatment and NER was not associated with aggression for adults who experienced low levels of childhood maltreatment. Moderating effects of childhood maltreatment on the NER-aggression link were supported for total childhood maltreatment, emotional neglect and emotional abuse. In contrast, HAB was more strongly associated with adult aggression at lower levels of emotional abuse and physical neglect.

CONCLUSIONS

The current study provides insight into the mechanisms by which early life experiences influence adult aggression. Our findings suggest that childhood maltreatment may not only lead to increased levels of aggression in adulthood but may also modify the associations between SIP and adult aggression.

PennTwins: A Population-Based Cohort for Twin Studies

The current article describes the creation and composition of the PennTwins Cohort and provides details on the demographic characteristics of the sample. The PennTwins Cohort was developed using a population-based method of ascertainment and currently has 9401 28- to 47-year-old twins, including 2225 confirmed twin pairs and 4951 twins whose co-twins have not yet registered. Zygosity data have been used to identify 919 monozygotic, 634 same-sex dizygotic, and 445 opposite-sex dizygotic pairs. GeoCode data on gender, age, and certain demographic characteristics were obtained for the addresses of all twins who were mailed invitations to be part of the cohort. Analysis of the available data show only very small differences between twins who are currently part of the PennTwins Cohort and potential twins who either did not respond to recruitment or who could not be located. Similarly, only very small demographic differences exist between twins from complete pairs and twins whose co-twins are not yet registered, and there are no differences across zygosity. Thus, despite a relatively low overall response rate (12% of all twins born in Pennsylvania from 1959–1978), there is no evidence that the sample differs in any meaningful respect from the larger population.

Genes, Environment, and Time: The Vietnam Era Twin Study of Aging (VETSA)

The Vietnam Era Twin Study of Aging (VETSA) is a large-scale investigation of cognitive aging from middle to later age. The intended sample of 1440 twin subjects is recruited from the Vietnam Era Twin Registry (VETR), a registry of middle-aged male-male twin pairs who both served in the military during the Vietnam conflict (1965–1975). VETSA employs a multitrait multimethod approach to cognitive assessment to focus on the genetic and environmental contributions to cognitive processes over time, as well as the relative contributions to cognitive aging from health, social, personality, and other contextual factors. The cognitive domains of episodic memory, working memory, abstract reasoning, and inhibitory executive functioning are assessed through neuropsychological testing. In addition, VETSA obtains the participant's score on the Armed Forces Qualification Test, taken at the time of induction into the military around age 20 years, and readministers the test. Two other projects — VETSA Cortisol and VETSA Magnetic Resonance Imaging — are also in progress using subsamples of the VETSA twins. Prior waves of data collection by VETSA investigators using the VETR have provided historical data on physical and mental health, while future waves of VETSA data collection are planned every 5 years. These methods will provide data on multiple pheno-types in the same individuals with regard to genetic and environmental contributions to cognitive functioning over time, personality and interpersonal risk and protective factors, stress and cortisol regulation, and structural brain correlates of aging processes.