Genetic Influences on Pubertal Development and Links to Behavior Problems

Genetic influences on adolescent psychological development are likely to be mediated and moderated by pubertal hormones. Combining genetic analyses with advanced models of pubertal development, we extended work on the measurement and psychological significance of puberty. We examined how genetic and environmental influences on puberty vary by the way that development is described (logistic versus linear models versus traditional methods) and the different aspects of puberty (adrenarche vs. gonadarche), and how genes and environment contribute to the covariation between different descriptions and aspects of puberty, and between pubertal development and behavior problems (substance use, age at sexual initiation). We also considered how puberty moderated the heritability of psychological outcomes (internalizing and externalizing problems), and sex differences. Participants from the Colorado Longitudinal Twin Study (403 girls, 395 boys) reported their pubertal development annually from ages 9 through 15; they and their parents reported their behavior in mid-to-late adolescence. There was a large genetic contribution to pubertal timing for both sexes no matter how it was measured, but findings for pubertal tempo varied by method. Genetic covariation accounted for most of the phenotypic correlations among different indicators of pubertal timing, and between pubertal timing and psychological outcome. We consider the implications of our results for understanding how pubertal hormones mediate or moderate genetic and environmental influences on psychological development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/123047/1/Genetic Influences on Pubertal Development and Links to Behavior Problems..pd

Modeling Pubertal Timing and Tempo and Examining Links to Behavior Problems

Research on the role of puberty in adolescent psychological development requires attention to the meaning and measurement of pubertal development. Particular questions concern the utility of self-report, the need for complex models to describe pubertal development, the psychological significance of pubertal timing vs. tempo, and sex differences in the nature and psychological significance of pubertal development. We used longitudinal self-report data to model linear and logistic trajectories of pubertal development, and used timing and tempo estimates from these models, and from traditional approaches (age at menarche and time from onset of breast development to menarche), to predict psychological outcomes of internalizing and externalizing behavior problems, and early sexual activity. Participants (738 girls, 781 boys) reported annually from ages 9 through 15 on their pubertal development, and they and their parents reported on their behavior in mid-to-late adolescence and early adulthood. Self-reports of pubertal development provided meaningful data for both boys and girls, producing good trajectories, and estimates of individuals' pubertal timing and tempo. A logistic model best fit the group data. Pubertal timing was estimated to be earlier in the logistic compared to linear model, but linear, logistic, and traditional estimates of pubertal timing correlated highly with each other and similarly with psychological outcomes. Pubertal tempo was not consistently estimated, and associations of tempo with timing and with behavior were model dependent. Advances in modeling facilitate the study of some questions about pubertal development, but assumptions of the models affect their utility in psychological studies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/123048/1/Modeling Pubertal Timing and Tempo and Examining Links to Behavior Problems.pd

Magnitude estimation of disfluency by stutterers and nonstutterers

UKEveryone produces disfluencies when they speak spontaneously. However, whereas most disfluencies pass unnoticed, the repetitions, blocks and prolongations produced by stutterers can have a severely disruptive effect on communication. The causes of stuttering have proven hard to pin down - researchers differ widely in their views on the cognitive mechanisms that underlie it. The present chapter presents initial research which supports a view (Vasic and Wijnen, this volume) that places the emphasis firmly on the self-monitoring system, suggesting that stuttering may be a consequence of over-sensitivity to the types of minor speech error that we all make. Our study also allows us to ask whether the speech of people who stutter is perceived as qualitatively different from that of nonstutterers, when it is fluent and when it contains similar types of minor disfluencies. Our results suggest that for closely matched, naturally occurring segments of speech, listeners rate the speech of stutterers as more disfluent than that of nonstutterers.caslAdams, F.R., Freeman, F.J., & Conture, E.G., (1985). Laryngeal dynamics of stutterers. In R.F. Curlee, W.H. Perkins, (Eds.), Nature and treatment of stuttering: New directions. San Diego, CA: College-Hill Press. Anderson, A.H., Bader, M., Bard, E.G., Boyle, E., Doherty, G., Garrod, S., Isard, S., Kowtko, J., McAllister, J., Miller, J., Sotillo, C., Thompson, H. & Weinert, R. (1991). The HCRC Map Task Corpus. Language and Speech, 34, 351-366 Bard, E.G. & Lickley, R.J. (1998). Graceful Failure in the Recognition of Running Speech. Proceedings of The 20th Annual Meeting of the Cognitive Science Society, University of Wisconsin-Madison, USA, pp.108-113. Bard, E.G., Robertson, D. & Sorace, A. (1996). Magnitude estimation of linguistic acceptability. Language, Vol. 72, No. 1, 32-68, Blackmer, E.R., & Mitton, J.L. (1991). Theories of monitoring and the timing of repairs in spontaneous speech. Cognition, 39, 173-194. Bloodstein, O. (1970). Stuttering and normal nonfluency: A continuity hypothesis. British Journal of Disorders of Communication, 1970, 30-39. Branigan, H., Lickley, R.J. & McKelvie, D. (1999). Non-linguistic influences on rates of disfluency in spontaneous speech. Proceedings of the ICPhS, International Congress on Phonetic Sciences, San Francisco, pp 387-390. Cohen, J.D., MacWhinney, B., Flatt, M. & Provost, J. (1993). Psyscope: A new graphic interactive environment for designing psychology experiments. Behavioral Research Methods, Instruments, and Computers, 25 (2), 257-271. Cross, D.E. (n.d.) A systems approach to stuttering. Retrieved 30 October, 2002, from http://www.ithaca.edu/cross/SPECIALIZATIONS/STUTTERING/Stuthome.html Dell, G.S. and Repka, R.J., (1992). Errors in inner speech. In B.J. Baars (Ed.), Experimental slips and human error: Exploring the architecture of volition. New York, NY: Plenum Press. Hartsuiker, R.J., & Kolk, H.H.J. (2001). Error monitoring in speech production: A computational test of the perceptual loop theory. Cognitive Psychology, 42, 113-157. Hartsuiker, R.J., Kolk, H.H.J. & Lickley, R.J. (2003). Stuttering on function words and content words: A computational test of the Covert Repair Hypothesis. In R.J. Hartsuiker, R. Bastiaanse, A. Postma, & F. Wijnen (Eds.), Phonological encoding and monitoring in normal and pathological speech. Hove (East Sussex): Psychology Press. Keller, F. (2000). Gradience in grammar: Experimental and computational aspects of degrees of grammaticality. Unpublished doctoral dissertation, University of Edinburgh. Keller, F. & Alexopoulou, T. (2001). Phonology competes with syntax: Experimental evidence for the interaction of word order and accent placement in the realization of information structure. Cognition, 79, 301-372. Laver, J.D.M., (1973). The detection and correction of slips of tongue. In V.A. Fromkin (Ed.), Speech errors as linguistic evidence. The Hague: Mouton. Laver, J.D.M., (1980). Monitoring systems in the neurolinguistic control of speech production. In V.A. Fromkin (Ed.), Errors in linguistic performance: Slips of the tongue, ear, pen, and hand. New York, NY: Academic Press. Levelt, W.J.M. (1983). Monitoring and self-repair in speech. Cognition, 14, 41-104. Levelt, W.J.M. (1989). Speaking: From intention to articulation. Cambridge, MA: MIT Press. Lickley, R.J. (1998). HCRC Disfluency Coding Manual. HCRC Technical Report. HCRC/TR-100, Human Communication Research Centre, University of Edinburgh. Lickley, R.J. (2001). Dialogue Moves and Disfluency Rates. In Proceedings of DiSS '01, Disfluency in spontaneous speech, ISCA Tutorial and Research Workshop, University of Edinburgh, pp 93-96. MacKay, D.G. (1987). The organization of perception and action: a theory for language and other cognitive skills. New York, NY: Springer. MacKay, D.G. (1992a). Awareness and error detection: New theories and research paradigms. Consciousness and Cognition, 1, 199-225. MacKay, D.G. (1992b). Errors, ambiguity, and awareness in language perception and production. In B.J. Baars (Ed.), Experimental slips and human error: Exploring the architecture of volition. New York, NY: Plenum Press. Melnick, K., Conture, E. & Ohde, R. (2003). Phonological Encoding in Young Children who Stutter. In R.J. Hartsuiker, R. Bastiaanse, A. Postma, & F. Wijnen (Eds.), Phonological encoding and monitoring in normal and pathological speech. Hove (East Sussex): Psychology Press. Perkins, W.H. (1990). What is stuttering? Journal of Speech and Hearing Disorders, 55, 370-382. Perkins, W.H. (1995). Stuttering and science. San Diego, CA: Singular Publishing Group. Postma, A. (2000). Detection of errors during speech production: a review of speech monitoring models. Cognition, 77, 97-131. Postma, A. and Kolk, H.H.J. (1992). Error monitoring in people who stutter: Evidence against auditory feedback defect theories. Journal of Speech and Hearing Research, 35, 1024-1032. Postma, A. & Kolk, H. (1993). The covert repair hypothesis: Prearticulatory repair processes in normal and stuttered disfluencies. Journal of Speech and Hearing Research, 36, 472-487. Raaijmakers, J.G.W., Schrijnemakers, J.M.C., & Gremmen, F. (1999). How to deal with The language-as-fixed-effect fallacy: Common misconceptions and alternative solutions. Journal of Memory and Language, 41, 416-426. Schiavetti, N., Sacco, P.R., Metz, D.E., & Sitler, R.W. (1983). Direct magnitude estimation and interval scaling of stuttering severity. Journal of Speech and Hearing Research, 26, 568- 573. Vasic, N. & Wijnen, F. (2003). Stuttering as a monitoring deficit. In R.J. Hartsuiker, R. Bastiaanse, A. Postma, & F. Wijnen (Eds.), Phonological encoding and monitoring in normal and pathological speech. Hove (East Sussex): Psychology Press. Van Riper, C. (1982). The Nature of Stuttering. Englewood Cliffs, NJ: Prentice-Hall. Wijnen, F. (2000). Stotteren als resultaat van inadequate spraakmonitoring [Stuttering as the result of inadequate speech monitoring]. Stem-, Spraak- en Taalpathologie, 9. Wood, S. (1995). An electropalatographic analysis of stutterers' speechE. uropean Journal of Disorders of Communication, 30, 226-236.1pub239pub

Revisiting Bloodstein's Anticipatory Struggle Hypothesis from a psycholinguistic perspective:A Variable Release Threshold hypothesis of stuttering

This paper reviews Bloodstein's (1975) Anticipatory Struggle Hypothesis of stuttering, identifies its weaknesses, and proposes modifications to bring it into line with recent advances in psycholinguistic theory. The review concludes that the Anticipatory Struggle Hypothesis provides a plausible explanation for the variation in the severity of stuttered disfluencies across speaking situations and conversation partners. However, it fails to explain the forms that stuttered disfluencies characteristically take or the subjective experience of loss of control that accompanies them. The paper then describes how the forms and subjective experiences of persistent stuttering can be accounted for by a threshold-based regulatory mechanism of the kind described in Howell's (2003) revision of the EXPLAN hypothesis. It then proposes that shortcomings of both the Anticipatory Struggle and EXPLAN hypotheses can be addressed by combining them together to create a 'Variable Release Threshold' hypothesis whereby the anticipation of upcoming difficulty leads to the setting of an excessively high threshold for the release of speech plans for motor execution. The paper also reconsiders the possibility that two stuttering subtypes exist: one related to formulation difficulty and other to difficulty initiating motor execution. It concludes that research findings that relate to the one may not necessarily apply to the other. Learning outcomes: After reading this article, the reader will be able to: (1) summarize the key strengths and weaknesses of Bloodstein's Anticipatory Struggle Hypothesis; (2) describe two hypothesized mechanisms behind the production of stuttered disfluencies (tension and fragmentation & release threshold mechanisms); and (3) discuss why the notion of anticipation is relevant to current hypotheses of stuttering. 2013 Elsevier Inc. All rights reserved.casl46pub3166pub

The Role of Attention-Deficit/hyperactivity Disorder in the Association between Verbal Ability and Conduct Disorder

Although there is clear evidence that low verbal ability is a risk factor for conduct disorder (CD), some researchers have questioned whether this association is due to the common comorbidity between attention-deficit/hyperactivity disorder (ADHD) and CD. The present study examined the association among verbal ability, ADHD, and CD in a genetically informative sample in order to examine the role of genes and/or environmental influences shared in common with ADHD on the covariation between verbal ability and CD. Participants were 2744 adolescents from the Center for Antisocial Drug Dependence (CADD), and included 360 monozygotic (MZ) female twin pairs, 221 dizygotic (DZ) female twin pairs, 297 MZ male twin pairs, 220 DZ male twin pairs, and 274 opposite-sex DZ twin pairs. The Diagnostic Interview Schedule for Children (DISC-IV) was used to assess lifetime symptoms of ADHD and CD. Verbal ability was assessed via the Vocabulary subtest of the Wechsler Adult Intelligence Scale III (WAIS-III) for individuals over the age of 16 and the Vocabulary subtest of the Wechsler Intelligence Scale for Children III (WISC-III) for individuals under the age of 16. There was a small but significant negative covariance between verbal ability and CD and between verbal ability and ADHD. Results also suggest that the covariation between verbal ability and CD is due to influences shared in common with ADHD

The Etiology of Observed Negative Emotionality from 14 to 24 Months

We examined the magnitude of genetic and environmental influences on observed negative emotionality at age 14, 20, and 24 months. Participants were 403 same-sex twin pairs recruited from the Longitudinal Twin Study whose emotional responses to four different situations were coded by independent raters. Negative emotionality showed significant consistency across settings, and there was evidence of a latent underlying negative emotionality construct. Heritability decreased, and the magnitude of shared environmental influences increased, for the latent negative emotionality construct from age 14 to 24 months. There were significant correlations between negative emotionality assessed at age 14, 20, and 24 months, and results suggested common genetic and shared environmental influences affecting negative emotionality across age, and that age-specific influences are limited to non-shared environmental influences, which include measurement error

Response to early literacy instruction in the United States, Australia, and Scandinavia A behavioral-genetic analysis

Abstract Genetic and environmental influences on early reading and spelling at the end of kindergarten and Grade 1 were compared across three twin samples tested in the United States, Australia, and Scandinavia. Proportions of variance due to genetic influences on kindergarten reading were estimated at .84 in Australia, .68 in the U.S., and .33 in Scandinavia. The effects of shared environment on kindergarten reading were estimated at .09 in Australia, .25 in the U.S., and .52 in Scandinavia. A similar pattern of genetic and environmental influences was obtained for kindergarten spelling. One year later when twins in all three samples had received formal literacy instruction for at least one full school year, heritability was similarly high across country, with estimated genetic influences varying between .79 and .83 for reading and between .62 and .79 for spelling. These findings indicate that the pattern of genetic and environmental influences on early reading and spelling development varies according to educational context, with genetic influence increasing as a function of increasing intensity of early instruction. Longitudinal analyses revealed genetic continuity for both reading and spelling between kindergarten and Grade 1 across country. However, a new genetic factor comes into play accounting for independent variance in reading at Grade 1 in the U.S. and Scandinavia, suggesting a change in genetic influences on reading. Implications for responseto-instruction are discussed. 4 Historically, and as late as 1800, more than 50% of the population in most western countries was illiterate. The opportunity to learn to read and write was a privilege, to a large extent determined by social-cultural conditions In this article, we continue to report on our International Longitudinal Twin Study (ILTS) of early language and literacy development The main purpose here was to compare genetic and environmental influences on early reading and spelling skills across three twin samples tested in the United States, Australia, and Scandinavia (i.e., Sweden and Norway) and across time of testing (i.e., kindergarten and Grade 1). Two questions are addressed: First, are there any differences in the pattern of genetic and environmental influences on early reading and spelling skills across country? Second, what are the changes in the pattern of genetic and environmental influences on reading and spelling from kindergarten to Grade 1? The general expectation is that the effects of environment on literacy skills should decrease and the genetic contribution increase as a function of intensity and consistency of instruction, across countries and time. This approach should also inform recent interest in response-to-intervention, or RTI, as a method to ascertain, define, and remediate 5 reading difficulties The ILTS has previously documented substantial effects of genes and relatively minor However, in a recent ILTS study of data collected near the end of kindergarten ), individual differences in reading and spelling skills were mainly 6 accounted for by genetic factors in a sample of Australian twins, with estimates of .91 and .84, respectively. In contrast, in a sample of U.S. twins from the state of Colorado, only approximately half of the variance in reading and spelling was accounted for by genetic influences, with the other half attributed to shared and non-shared environment. Although these country differences in genetic and environmental influences on individual differences in reading and spelling were not statistically significant with the available sample sizes, we hypothesized that the trends might be explained by country differences in educational practice. Compulsory school starts at around age five in both Australia and Colorado, but in New South Wales, Australian children enter a school system regulated by a state-wide curriculum mandating that at least 35% of a full school week (9 am to 3 pm, five days a week) should be devoted to language and literacy instruction. In contrast, in Colorado children attend kindergarten school for only 3-4 hours each day, and there is no state-mandated curriculum for teaching reading and spelling. One plausible explanation for the different pattern of genetic and environmental influences on reading and spelling in Australia and U.S. is that a state-wide curriculum emphasizing intense literacy instruction reduces the environmental range in the population, and thus, the amount of variance in reading and spelling skills that can be accounted for by environmental factors. Another explanation is that the greater intensity of instruction in NSW engages genetically-influenced learning processes earlier than in the US, resulting in a higher genetic contribution to overall variability. To further explore these hypotheses, the present study includes a sample of Scandinavian twins. In Scandinavia, compulsory school starts when the child is seven years old, that is, one to two years later compared to Australia and the U.S. Nevertheless, almost all children do attend kindergarten prior to compulsory attendance in Grade 1, but kindergarten curriculum in Sweden and Norway emphasizes social, emotional, and aesthetic development rather than early literacy acquisition. In this way, Scandinavia represents a population where environmental 7 variation outside of school might have a substantial impact on individual differences in kindergarten reading and spelling skills because there is no formal reading instruction in kindergarten. Instead, literacy socialization is mainly given informally at home. However, at seven years of age, in Grade 1, teaching reading and spelling is the target activity in school, and literacy instruction is guided by a master plan common to all schools in Sweden and Norway. This change from informal literacy teaching taking place at the children's home to a countrywide curriculum emphasizing formal reading and spelling instruction should reduce environmental range and increase the intensity of engagement. From kindergarten to Grade 1, we hypothesize, therefore, that the heritability of literacy skills increases and the importance of shared environment decreases in Scandinavia. To summarize, we hypothesize different contributions from genes and environment to kindergarten literacy skills across countries. We also hypothesize an increase in genetic effects on literacy from kindergarten to Grade 1, especially in Scandinavia where formal reading instruction is introduced one year later than in Australia and the U.S. These questions are addressed in the present study through univariate behavior-genetic analyses of data from identical and same-sex fraternal twins tested near the end of kindergarten and first grade. In addition to comparing the magnitudes of genetic and environmental influences between countries and grades in univariate analyses, with a multivariate approach we also address the question whether the same or different sources of genetic and environmental influences account for individual differences in literacy at kindergarten and Grade 1. Based on the differences in the curriculum for literacy instruction across countries summarized above, we hypothesize continuity in the pattern of genetic and environmental influences on reading and spelling from kindergarten to Grade 1 in Australia, but a possible change in genetic and environmental effects on literacy skills in Scandinavia, with the US representing an intermediate case. Method Participants The kindergarten sample comprised a total of 812 same-sex twin pairs recruited from the Colorado Twin Registry in the U.S., the National Heath and Medical Research Council's Australian Twin Registry, and from the Medical Birth Registries in Norway and Sweden (see Actual attrition because of families leaving the project is virtually zero. Only participants for whom the predominant language of their country (i.e., English, Swedish, or Norwegian) was the first language spoken at home were selected. There were no significant differences in parents' mean years of education across twin samples. Also, the means were around 14 years suggesting that level of education is representative for each country. Zygosity was determined by DNA analysis from cheek swab collection, or, in a minority of cases, by selected items from the questionnaire by Literacy skills Reading. Reading skills in kindergarten and Grade 1 were measured by both the word and nonword subtests from the Test of Word Reading Efficiency (TOWRE; Torgesen, Wagner, & Rashotte, 1999), with both Forms A and B administered and averaged to increase reliability (test-retest reliability for children aged 6-9 years, .97 for word and .90 for nonword standard scores). In each Form, children read a list of words and a list of nonwords as quickly as possible in 45 sec. A composite measure of reading skill was created for phenotypic analyses, justified by high correlations, .83 and .86 on average, between word and nonword reading at both kindergarten and at the end of Grade 1. For the behavior genetic analyses, we modelled the four subtests of word and nonword reading as latent traits. Spelling. At kindergarten, spelling was measured by a test developed by Byrne and Fielding- Procedure Children were assessed individually by trained examiners in their homes and/or schools at the end of kindergarten and Grade 1. To foster fidelity of assessment between testers and sites, we have adopted the practice of videotaping samples of test sessions and having each tester inspect the tapes of other testers. In this study, we only report on reading and spelling measures performed at each age. However, in single one-hour sessions at each of kindergarten and Grade 1, several other measures such as phonological awareness, RAN, and verbal abilities were included (for details, see Analysis One-way analyses of variance (ANOVA) and Tukey HSD post hoc tests were performed to test differences between country samples for reading and spelling at kindergarten and Grade 1. The magnitude of the mean differences was calculated using Cohen's d. Genetic and environmental influences on reading and spelling skills across country and within country 11 across time were analyzed using monozygotic (MZ) and dizygotic (DZ) twin correlations, and models were fitted from raw data using maximum likelihood estimation in Mx Results Reading and spelling skills across country Means and standard deviations for reading and spelling at kindergarten and Grade 1 across country and effect size estimations for mean differences are presented in Behavior-genetic analyses Standardized raw data adjusted for age and gender effects within each twin sample were used as input for all behavior-genetic analyses. To estimate the relative influence on individual differences from additive genetic effects (a 2 ), shared-environment effects (c 2 ), and nonsharedenvironment effects (e 2 ), the data for reading and spelling skills were subjected to structural equation modelling by use of the Mx statistical modelling package (Neale, Boker, Xie, & Maes, 2002). In this section, we start by presenting correlations between MZ and DZ twins

A Genetic Epidemiological Mega Analysis of Smoking Initiation in Adolescents

Introduction. Previous studies in adolescents were not adequately powered to accurately disentangle genetic and environmental influences on smoking initiation across adolescence. Methods. Mega-analysis of pooled genetically informative data on smoking initiation was performed, with structural equation modeling, to test equality of prevalence and correlations across cultural backgrounds, and to estimate the significance and effect size of genetic and environmental effects according to the classical twin study, in adolescent male and female twins from same-sex and opposite-sex twin pairs (N=19 313 pairs) between age 10 and 19, with 76 358 longitudinal assessments between 1983 and 2007, from 11 population-based twin samples from the US, Europe and Australia. Results. Although prevalences differed between samples, twin correlations did not, suggesting similar etiology of smoking initiation across developed countries. The estimate of additive genetic contributions to liability of smoking initiation increased from approximately 15% to 45% from age 13 to 19. Correspondingly, shared environmental factors accounted for a substantial proportion of variance in liability to smoking initiation at age 13 (70%) and gradually less by age 19 (40%). Conclusions. Both additive genetic and shared environmental factors significantly contribute to variance in smoking initiation throughout adolescence. The present study, the largest genetic epidemiological study on smoking initiation to date, found consistent results across 11 studies for the etiology of smoking initiation. Environmental factors, especially those shared by siblings in a family, primarily influence smoking initiation variance in early adolescence, while an increasing role of genetic factors is seen at later ages, which has important implications for prevention strategies. IMPLICATIONS: This is the first study to find evidence of genetic factors in liability to smoking initiation at ages as young as 12. It also shows the strongest evidence to date for decay of effects of the shared environment from early adolescence to young adulthood. We found remarkable consistency of twin correlations across studies reflecting similar etiology of liability to initiate smoking across different cultures and time periods. Thus familial factors strongly contribute to individual differences in who starts to smoke with a gradual increase in the impact of genetic factors and a corresponding decrease in that of the shared environment