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Hannigan LJ, Rijsdijk FV, Ganiban JM, Reiss D, Spotts EL, Neiderhiser JM, Lichtenstein P, McAdams TA, Eley TC. Shared genetic influences do not explain the association between parent-offspring relationship quality and offspring internalizing problems: results from a Children-of-Twins study. Psychol Med 2018; 48:592-603. [PMID: 28745264 PMCID: PMC5964471 DOI: 10.1017/s0033291717001908] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/14/2017] [Accepted: 06/15/2017] [Indexed: 01/20/2023]
Abstract
BACKGROUND Associations between parenting and child outcomes are often interpreted as reflecting causal, social influences. However, such associations may be confounded by genes common to children and their biological parents. To the extent that these shared genes influence behaviours in both generations, a passive genetic mechanism may explain links between them. Here we aim to quantify the relative importance of passive genetic v. social mechanisms in the intergenerational association between parent-offspring relationship quality and offspring internalizing problems in adolescence. METHODS We used a Children-of-Twins (CoT) design with data from the parent-based Twin and Offspring Study of Sweden (TOSS) sample [909 adult twin pairs and their offspring; offspring mean age 15.75 (2.42) years], and the child-based Swedish Twin Study of CHild and Adolescent Development (TCHAD) sample [1120 adolescent twin pairs; mean age 13.67 (0.47) years]. A composite of parent-report measures (closeness, conflict, disagreements, expressions of affection) indexed parent-offspring relationship quality in TOSS, and offspring self-reported internalizing symptoms were assessed using the Child Behavior Checklist (CBCL) in both samples. RESULTS A social transmission mechanism explained the intergenerational association [r = 0.21 (0.16-0.25)] in our best-fitting model. A passive genetic transmission pathway was not found to be significant, indicating that parental genetic influences on parent-offspring relationship quality and offspring genetic influences on their internalizing problems were non-overlapping. CONCLUSION These results indicate that this intergenerational association is a product of social interactions between children and parents, within which bidirectional effects are highly plausible. Results from genetically informative studies of parenting-related effects should be used to help refine early parenting interventions aimed at reducing risk for psychopathology.
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Affiliation(s)
- L. J. Hannigan
- Institute of Psychiatry, Psychology & Neuroscience, MRC Social, Genetic & Developmental Psychiatry Centre, King's College London, London, UK
| | - F. V. Rijsdijk
- Institute of Psychiatry, Psychology & Neuroscience, MRC Social, Genetic & Developmental Psychiatry Centre, King's College London, London, UK
| | - J. M. Ganiban
- Department of Psychology, The George Washington University, Washington, DC, USA
| | - D. Reiss
- Yale Child Study Center, New Haven, CT, USA
| | - E. L. Spotts
- Office of Behavioral and Social Science Research, NIH, Bethesda, MD, USA
| | - J. M. Neiderhiser
- Department of Psychology, The Pennsylvania State University, State College, PA, USA
| | - P. Lichtenstein
- Department of Medical Epidemiology and Biostatistics, Karolinksa Institutet, Stockholm, Sweden
| | - T. A. McAdams
- Institute of Psychiatry, Psychology & Neuroscience, MRC Social, Genetic & Developmental Psychiatry Centre, King's College London, London, UK
| | - T. C. Eley
- Institute of Psychiatry, Psychology & Neuroscience, MRC Social, Genetic & Developmental Psychiatry Centre, King's College London, London, UK
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McAdams TA, Rijsdijk FV, Neiderhiser JM, Narusyte J, Shaw DS, Natsuaki MN, Spotts EL, Ganiban JM, Reiss D, Leve LD, Lichtenstein P, Eley TC. The relationship between parental depressive symptoms and offspring psychopathology: evidence from a children-of-twins study and an adoption study. Psychol Med 2015; 45:2583-2594. [PMID: 25994116 PMCID: PMC4523449 DOI: 10.1017/s0033291715000501] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Parental depressive symptoms are associated with emotional and behavioural problems in offspring. However, genetically informative studies are needed to distinguish potential causal effects from genetic confounds, and longitudinal studies are required to distinguish parent-to-child effects from child-to-parent effects. METHOD We conducted cross-sectional analyses on a sample of Swedish twins and their adolescent offspring (n = 876 twin families), and longitudinal analyses on a US sample of children adopted at birth, their adoptive parents, and their birth mothers (n = 361 adoptive families). Depressive symptoms were measured in parents, and externalizing and internalizing problems measured in offspring. Structural equation models were fitted to the data. RESULTS Results of model fitting suggest that associations between parental depressive symptoms and offspring internalizing and externalizing problems remain after accounting for genes shared between parent and child. Genetic transmission was not evident in the twin study but was evident in the adoption study. In the longitudinal adoption study child-to-parent effects were evident. CONCLUSIONS We interpret the results as demonstrating that associations between parental depressive symptoms and offspring emotional and behavioural problems are not solely attributable to shared genes, and that bidirectional effects may be present in intergenerational associations.
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Affiliation(s)
- T. A. McAdams
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology and
Neuroscience, King's College London,
London, UK
| | - F. V. Rijsdijk
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology and
Neuroscience, King's College London,
London, UK
| | | | - J. Narusyte
- Department of Clinical Neusroscience,
Karolinska Institutet, Stockholm,
Sweden
| | - D. S. Shaw
- Department of Psychology,
University of Pittsburgh, USA
| | - M. N. Natsuaki
- Department of Psychology,
University of California Riverside, USA
| | - E. L. Spotts
- Office of Behavioral and Social Science
Research, NIH, Bethesda,
MD, USA
| | - J. M. Ganiban
- Department of Psychology,
George Washington University,
Washington, DC, USA
| | - David Reiss
- Child Study Center, Yale
University, New Haven, CT,
USA
| | - L. D. Leve
- Department of Counseling Psychology and Human
Services, University of Oregon, and Oregon Social Learning
Center, Eugene, Oregon,
USA
| | - P. Lichtenstein
- Department of Medical Epidemiology and
Biostatistics, Karolinksa Institute,
Stockholm, Sweden
| | - T. C. Eley
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology and
Neuroscience, King's College London,
London, UK
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Owens SF, Picchioni MM, Rijsdijk FV, Stahl D, Vassos E, Rodger AK, Collier DA, Murray RM, Toulopoulou T. Genetic overlap between episodic memory deficits and schizophrenia: results from the Maudsley Twin Study. Psychol Med 2011; 41:521-532. [PMID: 20459888 DOI: 10.1017/s0033291710000942] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Visual and verbal episodic memory deficits are putative endophenotypes for schizophrenia; however, the extent of any genetic overlap of these with schizophrenia is unclear. In this study, we set out to quantify the genetic and environmental contributions to variance in visual and verbal memory performance, and to quantify their genetic relationship with schizophrenia. METHOD We applied bivariate genetic modelling to 280 twins in a classic twin study design, including monozygotic (MZ) and dizygotic (DZ) pairs concordant and discordant for schizophrenia, and healthy control twins. We assessed episodic memory using subtests of the Wechsler Memory Scale - Revised (WMS-R). RESULTS Genetic influences (i.e. heritability) contributed significantly to variance in immediate recall of both verbal memory and visual learning, and the delayed recall of verbal and visual memory. Liability to schizophrenia was associated with memory impairment, with evidence of significant phenotypic correlations between all episodic memory measures and schizophrenia. Genetic factors were the main source of the phenotypic correlations for immediate recall of visual learning material; both immediate and delayed recall of verbal memory; and delayed recall of visual memory that, for example, shared genetic variance with schizophrenia, which accounted for 88% of the phenotypic correlation (rph=0.41) between the two. CONCLUSIONS Verbal memory and visual learning and memory are moderately heritable, share a genetic overlap with schizophrenia and are valid endophenotypes for the condition. The inclusion of these endophenotypes in genetic association studies may improve the power to detect susceptibility genes for schizophrenia.
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Affiliation(s)
- S F Owens
- Department of Psychosis Studies, Institute of Psychiatry, King's College London, King's Health Partners, UK.
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Abstract
BACKGROUND Prior research on the nature of the vulnerability of neuroticism to psychopathology suggests biases in information processing towards emotional rather than neutral information. It is unclear to what extent this relationship can be explained by genetic or environmental factors. METHOD The genetic relationship between a neuroticism composite score and free recall of pleasant and unpleasant words and the reaction time on negative probes (dot-probe task) was investigated in 125 female twin pairs. Interaction effects were modelled to test whether the correlation between neuroticism and cognitive measures depended on the level of the neuroticism score. RESULTS The only significant correlation was between neuroticism and the proportion of recalled unpleasant words (heritability is 30%), and was only detectable at the higher end of the neuroticism distribution. This interaction effect seems to be due to environmental effects that make people in the same family more similar (e.g. parental discipline style), rather than genetic factors. An interesting sub-finding was that faster reaction times for left versus right visual field probes in the dot-probe task suggest that cognitive processing in the right hemisphere is more sensitive to subliminal (biologically relevant) cues and that this characteristic is under substantial genetic control (49%). Individual differences in reaction times on right visual field probes were due to environmental effects only. CONCLUSIONS There is no evidence that the predisposition of individuals to focus on negative (emotional) stimuli is a possible underlying genetic mechanism of neuroticism.
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Affiliation(s)
- F V Rijsdijk
- Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, London, UK.
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Ormel J, Rijsdijk FV, Riese H, Snieder H, Rosmalen JGM. Comment on: Kendler KS, Myers J, Torgersen S, Neale MC, Reichborn-Kjennerud T. (2007) The heritability of cluster A personality disorders assessed by both personal interview and questionnaire. Psychol Med; 37:655-665. Psychol Med 2008; 38:153-154. [PMID: 18329980 DOI: 10.1017/s003329170700150x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Campbell DD, Rijsdijk FV, Sham PC. Computation of individual latent variable scores from data with multiple missingness patterns. Behav Genet 2006; 37:408-22. [PMID: 17120140 DOI: 10.1007/s10519-006-9123-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Accepted: 10/16/2006] [Indexed: 11/30/2022]
Abstract
Latent variable models are used in biological and social sciences to investigate characteristics that are not directly measurable. The generation of individual scores of latent variables can simplify subsequent analyses. However, missing measurements in real data complicate the calculation of scores. Missing observations also result in different latent variable scores having different degrees of accuracy which should be taken into account in subsequent analyses. This manuscript presents a publicly available software tool that addresses both these problems, using as an example a dataset consisting of multiple ratings for ADHD symptomatology in children. The program computes latent variable scores with accompanying accuracy indices, under a 'user-specified' structural equation model, in data with missing data patterns. Since structural equation models encompass factor models, it can also be used for calculating factor scores. The program, documentation and a tutorial, containing worked examples and specimen input and output files, is available at http://statgen.iop.kcl.ac.uk/lsc .
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Affiliation(s)
- D D Campbell
- MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, De Crespigny Park, Box P080, London, SE5 8AF, UK.
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Rijsdijk FV, van Haren NEM, Picchioni MM, McDonald C, Toulopoulou T, Hulshoff Pol HE, Kahn RS, Murray R, Sham PC. Brain MRI abnormalities in schizophrenia: same genes or same environment? Psychol Med 2005; 35:1399-1409. [PMID: 16164764 DOI: 10.1017/s0033291705005167] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Structural brain volume abnormalities are among the most extensively studied endophenotypes in schizophrenia. Bivariate genetic model fitting (adjusted to account for selection) was used to quantify the genetic relationship between schizophrenia and brain volumes and to estimate the heritability of these volumes. METHOD We demonstrated by simulation that the adjusted genetic model produced unbiased estimates for endophenotype heritability and the genetic and environmental correlations. The model was applied to brain volumes (whole brain, hippocampus, third and lateral ventricles) in a sample of 14 monozygotic (MZ) twin pairs concordant for schizophrenia, 10 MZ discordant pairs, 17 MZ control pairs, 22 discordant sibling pairs, three concordant sibling pairs, and 114 healthy control subjects. RESULTS Whole brain showed a substantial heritability (88%) and lateral ventricles substantial common environmental effects (67%). Whole brain showed a significant genetic correlation with schizophrenia, whereas lateral ventricles showed a significant individual specific correlation with schizophrenia. There were significant familial effects for hippocampus and third ventricle, but the analyses could not resolve whether these were genetic or environmental in origin (around 30%each). CONCLUSIONS Using genetic model fitting on twin and sibling data we have demonstrated differential sources of covariation between schizophrenia and brain volumes, genetic in the case of whole brain volume and individual specific environment in the case of lateral ventricles.
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Affiliation(s)
- F V Rijsdijk
- Social, Genetic & Developmental Psychiatry Research Centre, Institute of Psychiatry, London, UK.
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Abstract
We present a regression-based method of haplotype association analysis for quantitative and dichotomous traits in samples consisting of unrelated individuals. The method takes account of uncertain phase by initially estimating haplotype frequencies and obtaining the posterior probabilities of all possible haplotype combinations in each individual, then using these as weights in a finite mixture of regression models. Using this method, different combinations of marker loci can be modeled, to find a parsimonious set of marker loci that are most predictive and therefore most likely to be closely associated with the a quantitative trait locus. The method has the additional advantage of being able to use individuals with some missing genotype data, by considering all possible genotypes at the missing markers. We have implemented this method using the SNPHAP and Mx programs and illustrated its use on published data on idiopathic generalized epilepsy.
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Affiliation(s)
- P C Sham
- Social, Genetic, and Developmental Psychiatry Research Centre, Institute of Psychiatry, P.O. 080, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom.
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Rijsdijk FV, Snieder H, Ormel J, Sham P, Goldberg DP, Spector TD. Genetic and environmental influences on psychological distress in the population: General Health Questionnaire analyses in UK twins. Psychol Med 2003; 33:793-801. [PMID: 12877394 DOI: 10.1017/s0033291703007451] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The General Health Questionnaire (GHQ) is the most popular screening instrument for detecting psychiatric disorders in community samples. Using longitudinal data of a large sample of UK twin pairs, we explored (i) heritabilities of the four scales and the total score; (ii) the genetic stability over time; and (iii) the existence of differential heritable influences at the high (ill) and low (healthy) tail of the distribution. METHOD At baseline we assessed the GHQ in 627 MZ and 1323 DZ female pairs and at a second occasion (3.5 years later) for a small subsample (90 MZ and 270 DZ pairs). Liability threshold models and raw ordinal maximum likelihood were used to estimate twin correlations and to fit longitudinal genetic models. We estimated extreme group heritabilities of the GHQ distribution by using a model-fitting implementation of the DeFries-Fulker regression method for selected twin data. RESULTS Heritabilities for Somatic Symptoms, Anxiety, Social Dysfunction, Depression and total score were 0.37, 0.40, 0.20, 0.42 and 0.44, respectively. The contribution of shared genetic factors to the correlations between time points is substantial for the total score (73%). Group heritabilities of 0.48 and 0.43 were estimated for the top and bottom 10% of the total GHQ score distribution, respectively. CONCLUSION The overall heritability of the GHQ as a measure of psychosocial distress was substantial (44%), with all scales having significant additive genetic influences that persisted across time periods. Extreme group analyses suggest that the genetic control of resilience is as important as the genetic control of vulnerability.
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Affiliation(s)
- F V Rijsdijk
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry and Twin Research and Genetic Epidemiology Unit. St Thomas' Hospital, London
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Rijsdijk FV, Hewitt JK, Sham PC. Analytic power calculation for QTL linkage analysis of small pedigrees. Eur J Hum Genet 2001; 9:335-40. [PMID: 11378821 DOI: 10.1038/sj.ejhg.5200634] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2000] [Revised: 01/02/2001] [Accepted: 01/09/2001] [Indexed: 11/09/2022] Open
Abstract
Power calculation for QTL linkage analysis can be performed via simple algebraic formulas for small pedigrees, but requires intensive computation for large pedigrees, in order to evaluate the expectation of the test statistic over all possible inheritance vectors at the test position. In this report, we show that the non-centrality parameter for an arbitrary pedigree can be approximated by the sum of the variances of the correlations between all pairs of relatives, each variance being weighted by a factor that is determined by the mean correlation of the pair. We show that this approximation is sufficiently accurate for practical purposes in small to moderately large pedigrees, and that large sibships are more efficient than other family structures under a range of genetic models.
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Affiliation(s)
- F V Rijsdijk
- Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, London SE5 8AF, UK.
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Rijsdijk FV, Sham PC, Sterne A, Purcell S, McGuffin P, Farmer A, Goldberg D, Mann A, Cherny SS, Webster M, Ball D, Eley TC, Plomin R. Life events and depression in a community sample of siblings. Psychol Med 2001; 31:401-410. [PMID: 11305848 DOI: 10.1017/s0033291701003361] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND The overall aim of the GENESiS project is to identify quantitative trait loci (QTLs) for anxiety/depression, and to examine the interaction between these loci and psychosocial adversity. Here we present life-events data with the aim of clarifying: (i) the aetiology of life events as inferred from sibling correlations; (ii) the relationship between life events and measures of anxiety and depression, as well as neuroticism; and (iii) the interaction between life events and neuroticism on anxiety/depression indices. METHODS We assessed the occurrence of one network and three personal life-event categories and multiple indices of anxiety/depression including General Health Questionnaire, Anhedonic Depression, Anxious Arousal and Neuroticism in a large community-based sample of2150 sib pairs, 410 trios and 81 quads. Liability threshold models and raw ordinal maximum likelihood were used to estimate within-individual and between-sibling correlations of life events. The relationship between life events and indices of emotional states and personality were assessed by multiple linear regression and canonical correlations. RESULTS Life events showed sibling correlations of 0-37 for network events and between 0-10 and 0.19 for personal events. Adverse life events were related to anxiety and depression and, to a less extent, neuroticism. Trait-vulnerability (as indexed by co-sib's neuroticism, anxiety and depression) accounted for 11% and life events for 3% of the variance in emotional states. There were no interaction effects. CONCLUSIONS Life events show moderate familiality and are significantly related to symptoms of anxiety and depression in the community. Appropriate modelling of life events in linkage and association analyses should help to identify QTLs for depression and anxiety.
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Affiliation(s)
- F V Rijsdijk
- Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, London
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Abstract
The relationship of speed-of-information-processing (SIP), as derived from reaction times (RTs) on experimental tasks, and intelligence has been extensively studied. SIP is suggested to measure the efficiency with which subjects can perform basic cognitive operations underlying a wide range of intellectual abilities. Observed phenotypic correlations between RT and IQ typically are in the -0.2 to -0.4 range, and the question is addressed to what extent this relationship is determined by genetic or environmental influences. In a group of Dutch twins the heritabilities for RT tasks at age 16 and 18 years were estimated longitudinally and the nature of the RT-IQ relationship was investigated. At age 16 years heritabilities for a simple reaction time (SRT) and choice reaction time (CRT) were 64 and 62% and the average phenotypic correlations between the RTs and IQ, assessed by the Raven standard progressive matrices, was -0.21. At the second test occasion lower heritabilities were observed for the RTs, probably due to modifications in administration procedures. The mean correlations between the RTs and WAIS verbal and per formal subtests were -0.18 and -0.16. Multivariate genetic analyses at both ages showed that the RT-IQ correlations were explained by genetic influences. These results are in agreement with earlier findings (Baker et al., Behav Genet 1991;21:351-67; Ho et al., Behav Genet 1988;18:247-61) and support the existence of a common, heritable biological basis underlying the SIP-IQ relationship.
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Affiliation(s)
- F V Rijsdijk
- Department of Psychonomics, Vrije Universiteit, Amsterdam, The Netherlands.
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Abstract
Variation in peripheral nerve conduction velocity (PNCV) and intelligence was studied in 18-year-old Dutch twins. It has been suggested that both brain nerve conduction velocity and PNCV are positively correlated with intelligence (Reed, 1984) and that heritable differences in nerve conduction velocity may explain part of the well-established heritability of intelligence. The relationship among IQ, obtained with the Wechsler Adult Intelligence Scale, and median nerve PNCV was examined in 159 twin pairs. Genetic analyses showed a heritability of 81% for IQ and 66% for onset PNCV. The small but significant phenotypic correlation between IQ and onset PNCV (.15) was entirely mediated by common genetic factors. Analyses of differences scores for PNCV of this study and PNCV from the same subjects collected at age 16 suggest that there might still be development in PNCV in this age interval. This maturation is highly controlled by genetic factors. It is suggested that variation in IQ that is associated with nerve conduction velocity becomes apparent only after the developmental processes in peripheral nerves are completed. This is in line with the suggestion of increasing heritability of IQ in adulthood.
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Affiliation(s)
- F V Rijsdijk
- Department of Psychonomics, Vrije Universiteit, Amsterdam, The Netherlands.
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Abstract
We studied variation in peripheral nerve conduction velocity (PNCV) and intelligence in a group of 16-year-old Dutch twins. It has been suggested that both brain nerve conduction velocity and PNCV are positively correlated with intelligence (Reed, 1984) and that heritable differences in NCV may explain part of the well established heritability of intelligence. The Standard Progressive Matrices test was administered to 210 twin pairs to obtain IQ scores. Median nerve PNCV was determined in a subgroup of 156 pairs. Genetic analyses showed a heritability of 0.65 for Raven IQ score and 0.77 for PNCV. However, there was no significant phenotypic correlation between IQ score and PNCV.
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Affiliation(s)
- F V Rijsdijk
- Department of Psychonomics, Vrije Universiteit, Amsterdam, The Netherlands
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Abstract
In this study 12 depressed outpatients were compared to 12 healthy controls with respect to their performance on a number of cognitive tasks, including a recognition-memory task, and their eye movements and pupil size were recorded while watching a traffic film. The recognition-memory task consisted of words with intermediate hedonic tone (neutral words), words with high hedonic tone ('good' words) and words with low hedonic tone ('bad' words). Patients performed slower on perceptual-motor tasks which could be characterized as effort-demanding, while no difference between groups was found on effortless tasks. In addition, the range of horizontal eye movements, an indication of visual span, was found to be less in patients. Signal-detection analysis on the recognition-memory data showed an impairment of 'pure' memory in depressives. Analyses on response bias indicated that patients had more false alarms, but only with respect to good words. It is concluded that patients exhibit cognitive deficits, including memory impairment, a narrower visual span and a risky response strategy on good words, which may be an indication of the trouble patients have in processing emotionally toned words.
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Affiliation(s)
- J B Deijen
- Department of Psychophysiology, Vrije Universiteit, Amsterdam, The Netherlands
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