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Aydoğan Avşar P, Kara T, Kocaman O, Akkuş M. The relationship between digit ratio (2D:4D) and intelligence levels in specific learning disorders. Early Hum Dev 2024; 196:106085. [PMID: 39084185 DOI: 10.1016/j.earlhumdev.2024.106085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 07/25/2024] [Accepted: 07/26/2024] [Indexed: 08/02/2024]
Abstract
BACKGROUND Higher prenatal testosterone exposure regulates brain development and affects learning and intelligence directly. The digit ratio (2D:4D) is regarded as an indicator of prenatal testosterone exposure. This study aims to investigate the 2D:4D ratios and intelligence levels in individuals with specific learning disorders (SLD) and compare the ratios with healthy subjects. METHODS The study included a total of 117 patients diagnosed with SLD and 67 healthy controls. We measured the 2D:4D ratios and administered the Wechsler-Intelligence Scale for Children-Revised to assess intelligence quotient (IQ) scores in the SLD group. Sociodemographic data was obtained for both patients and healthy subjects and compared in both groups, as well as 2D:4D ratios. RESULTS Compared to healthy controls, both-hand 2D:4D ratios were found to be lower in the SLD group. In addition, male and female participants with SLD showed lower 2D:4D ratios in both hands than controls. The total scores on the WISC-R were found to decrease as the right-hand 2D:4D ratios and the age increased in the SLD group. CONCLUSION Our findings add to the literature examining the influence of prenatal testosterone exposure on learning and intelligence in the SLD sample. Further research in this domain may yield valuable insights into the underlying mechanisms and potential clinical implications for the management of SLDs examining additional variables that could potentially impact alongside the impact of sex hormones on brain development.
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Affiliation(s)
- Pınar Aydoğan Avşar
- Department of Child and Adolescent Psychiatry, Alanya Education and Research Hospital, Antalya 07425, Turkey.
| | - Tayfun Kara
- Department of Child and Adolescent Psychiatry, Alanya Alaaddin Keykubat University Faculty of Medicine, Antalya 07425, Turkey
| | - Orhan Kocaman
- Department of Child and Adolescent Psychiatry, Alanya Alaaddin Keykubat University Faculty of Medicine, Antalya 07425, Turkey
| | - Merve Akkuş
- Department of Psychiatry, Faculty of Medicine, Kütahya Health Sciences University, Kütahya 43100, Turkey
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2
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Jägetoft Z, Unenge Hallerbäck M, Julin M, Bornehag CG, Wikström S. Anthropometric measures do not explain the 2D:4D ratio sexual dimorphism in 7-year-old children. Am J Hum Biol 2022; 34:e23776. [PMID: 35751545 PMCID: PMC9540332 DOI: 10.1002/ajhb.23776] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 12/05/2022] Open
Abstract
Objectives Digit ratio (2D:4D) might reflect prenatal testosterone exposure and has been used as a putative marker for androgen related outcomes. However, such associations might be inflicted by confounders. Application of 2D:4D in epidemiological research motivate identification of biological background determinants. We examined sex, anthropometric measures, and maternal factors as determinants of 2D:4D in Swedish 7‐year‐old children. Methods The study was embedded in the Swedish Environmental, Longitudinal, Mother and Child, Asthma and Allergy (SELMA) pregnancy cohort. A total of 870 pre‐pubertal children, median 7.5 years of age, were studied. A single assessor performed digit measurements from scanned photocopies using computer software. Child anthropometric measurements investigated were hand size, birthweight, recumbent birth length, standing height, weight, BMI, body fat percentage, and waist/hip circumference. Maternal factors included age, pregnancy length, parity, and education. Results We found a significant sexual dimorphism regarding digit lengths and 2D:4D, boys on average presenting a lower 2D:4D than girls also after adjustment for summed finger lengths and body fatness. In crude analyses, maternal age correlated with 2D:4D across the whole population and in females but not in adjusted models. No other study variables were associated with 2D:4D. Conclusion Digit ratio showed sexual dimorphism at the age of seven and seems to represent a true sex difference rather than an artifact and bias from hand size, body size or body fat content. Among the rest of our investigated variables, we found no determinants constituting important confounders in future research on 2D:4D ratio.
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Affiliation(s)
- Zebulohn Jägetoft
- Centre for Research and Education, County Council of Värmland, Karlstad, Sweden
| | - Maria Unenge Hallerbäck
- Centre for Research and Education, County Council of Värmland, Karlstad, Sweden.,Department of Health Sciences, Karlstad University, Karlstad, Sweden.,School of Medical Science, Örebro University, Örebro, Sweden
| | - Maria Julin
- Västerås Hospital, County Council of Västmanland, Västerås, Sweden
| | - Carl-Gustaf Bornehag
- Department of Health Sciences, Karlstad University, Karlstad, Sweden.,Department of Preventive Medicine, Ichan School of Medicine at Mount Sinai, New York, New York, USA
| | - Sverre Wikström
- Centre for Research and Education, County Council of Värmland, Karlstad, Sweden.,Department of Health Sciences, Karlstad University, Karlstad, Sweden.,School of Medical Science, Örebro University, Örebro, Sweden
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3
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Kobus M, Sitek A, Antoszewski B, Rożniecki J, Pełka J, Żądzińska E. Prenatal oestrogen-testosterone balance as a risk factor of migraine in adults. J Headache Pain 2021; 22:119. [PMID: 34620097 PMCID: PMC8499432 DOI: 10.1186/s10194-021-01326-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/07/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Migraine is a common neurological disease with extremely debilitating, but fully reversible symptoms. Women suffer from migraine more often than men. It was assumed that fluctuation of oestrogen level during menstrual cycle is one of many factors responsible for more frequent migraine attacks. The second-to-fourth digit ratio (2D:4D) is considered as an indicator of prenatal sex steroids. Balance of prenatal androgens (testosterone) and oestrogen has been studied in numerous diseases that are affected by hormones. However, the relationship between migraine and the sex steroids balance in prenatal development is still unexplained. The aim of this paper is to provide an evidence of relationship between prenatal oestrogen and testosterone exposure following 2D:4D digit ratio, and migraine prevalence in adults. METHODS We examined a group of 151 adults (33 males, 118 females) with migraine and a control group of 111 adults (45 males, 66 females). 2D:4D digit ratio of both hands was measured using sliding Vernier calliper. RESULTS Significant differences were found in the right hand. Female migraineurs had lower value of 2D:4D ratio than the control group and the right 2D:4D was lower than left 2D:4D (Δ2D:4D), suggesting prenatal testosterone dominance. The opposite relationship was observed in males. Male migraineurs had higher value of 2D:4D ratio and Δ2D:4D was greater than the control group, suggesting prenatal oestrogen dominance. CONCLUSIONS Our results suggest that depending on sex, different proportion of prenatal sex steroids might be a risk factor of migraine in adults. Women with migraine were presumably exposed in prenatal life to higher testosterone levels relative to oestrogen, while men with migraine were probably exposed in prenatal life to higher levels of oestrogen relative to testosterone.
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Affiliation(s)
- Magdalena Kobus
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland.
| | - Aneta Sitek
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland
| | - Bogusław Antoszewski
- Department of Plastic, Reconstructive and Aesthetic Surgery, Institute of Surgery, Medical University of Lodz, Lodz, Poland
| | - Jacek Rożniecki
- Department of Neurology, Stroke and Neurorehabilitation, Medical University of Lodz, Lodz, Poland
| | - Jacek Pełka
- Department of Neurology, Norbert Barlicki Memory University Teaching Hospital, Lodz, Poland
| | - Elżbieta Żądzińska
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland
- Biological Anthropology and Comparative Anatomy Research Unit, School of Medicine, The University of Adelaide, Adelaide, South Australia, 5005, Australia
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4
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Myers L, Pan P, Remnélius KL, Neufeld J, Marschik PB, Jonsson U, Bölte S. Behavioral and biological divergence in monozygotic twin pairs discordant for autism phenotypes: A systematic review. JCPP ADVANCES 2021. [DOI: 10.1111/jcv2.12017] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Lynnea Myers
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
- Department of Nursing Gustavus Adolphus College St. Peter Minnesota USA
| | - Pei‐Yin Pan
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
| | - Karl Lundin Remnélius
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
| | - Janina Neufeld
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
| | - Peter B. Marschik
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
- Department of Child and Adolescent Psychiatry and Psychotherapy University Medical Center Göttingen & Leibniz Science Campus Göttingen Germany
- Department of Phoniatrics D –Interdisciplinary Developmental Neuroscience Medical University of Graz Graz Steiermark Austria
| | - Ulf Jonsson
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
- Department of Neuroscience, Child and Adolescent Psychiatry Uppsala University Uppsala Sweden
| | - Sven Bölte
- Department of Women's and Children's Health Karolinska Institutet Center of Neurodevelopmental Disorders Centre for Psychiatry Research Karolinska Institutet & Stockholm Health Care Services Stockholm Sweden
- Department of Child and Adolescent Psychiatry Stockholm Health Care Services Stockholm Sweden
- Curtin Autism Research Group School of Occupational Therapy, Social Work and Speech Pathology Curtin University Perth Western Australia Australia
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5
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Zhang J, Yang M, Luan P, Jia W, Liu Q, Ma Z, Dang J, Lu H, Ma Q, Wang Y, Mu C, Huo Z. Associations Between Cytochrome P450 (CYP) Gene Single-Nucleotide Polymorphisms and Second-to-Fourth Digit Ratio in Chinese University Students. Med Sci Monit 2021; 27:e930591. [PMID: 33723203 PMCID: PMC7980499 DOI: 10.12659/msm.930591] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/22/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Cytochrome P450 (CYP) genes are necessary for the production or metabolism of fetal sex hormones during pregnancy. The second-to-fourth digit ratio (2D: 4D) is formed in the early stage of human fetal development and considered an indicator reflecting prenatal sex steroids levels. We explored the association between 2D: 4D and single-nucleotide polymorphisms (SNPs) of CYP. MATERIAL AND METHODS Correlation analysis between 2D: 4D and 8 SNPs, rs2687133 (CPY3A7), rs7173655 (CYP11A1), rs1004467, rs17115149, and rs2486758 (CYP17A1), and rs4646, rs2255192, rs4275794 (CYP19A1), was performed using data from 426 female and 412 male Chinese university students. SNP genotyping was conducted using PCR. Digit lengths were photographed and measured by image processing software. RESULTS rs2486758 (CYP17A1) correlated with left hand 2D: 4D in men (P=0.026), and rs1004467 (CYP17A1) correlated with right hand 2D: 4D in men (P=0.008) and the whole population (P=0.032). In men, allele G rs1004467 decreased right hand 2D: 4D, while allele C of rs2486758 increased left hand 2D: 4D. In women, left hand 2D: 4D was higher in genotypes with allele A of SNP rs4646 (CYP19A1) under the dominant genetic model; female DR-L was higher in genotypes with allele T of rs17115149 (CYP11A1). SNPs rs2687133 (CYP3A7) and rs1004467 (CYP17A1) were significantly correlated with right hand 2D: 4D (P=0.0107). CONCLUSIONS SNPs rs1004467 and rs2486758 of CYP17A1 are significant in the relationship between 2D: 4D and CYP gene polymorphisms under different conditions. SNP interactions between CYP genes probably impact 2D: 4D. The correlation between 2D: 4D and some sex hormone-related diseases may be due to the effect of CYP variants on the 2 phenotypes.
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Affiliation(s)
- Jing Zhang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Mengyi Yang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Pengfei Luan
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Wei Jia
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Qiujun Liu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Zhanbing Ma
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Jie Dang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Hong Lu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Qian Ma
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Yanfeng Wang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Chunlan Mu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Zhenghao Huo
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
- Department of Biology, Gansu Medical College, Pingliang, Gansu, P.R. China
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6
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Richards G, Medland SE, Beaton AA. Digit ratio (2D:4D) and handedness: A meta-analysis of the available literature. Laterality 2021; 26:421-484. [PMID: 33517845 DOI: 10.1080/1357650x.2020.1862141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Geschwind-Behan-Galaburda and sexual differentiation models predict an association between elevated foetal androgen exposure and left-handedness whereas the callosal hypothesis predicts the opposite. We present a meta-analysis of correlations between handedness and digit ratio (2D:4D), a putative marker of prenatal testosterone. Left-handedness predicted low (male-typical) right-hand digit ratio (R2D:4D), high (female-typical) left-hand digit ratio (L2D:4D), and low R2D:4D-L2D:4D directional asymmetry (D[R-L]). Effect sizes were extremely small and not moderated by sex or method of measuring handedness or 2D:4D. The same general pattern was observed after excluding the very large study (110,329 males, 90,412 females) of Manning and Peters ([2009]. Digit ratio (2D:4D) and hand preference for writing in the BBC Internet Study. Laterality: Asymmetries of Body, Brain and Cognition, 14(5), 528-540. doi:10.1080/13576500802637872); however, no significant effects for R2D:4D were observed once these samples were removed. The results do not confirm any theory linking prenatal androgens with handedness, so we speculate they instead reflect the mechanical action of writing causing subtle changes in the musculature and/or fat pads of the fingers. Gripping a pen/pencil might cause an increase in 2D relative to 4D (and/or decrease in 4D relative to 2D) resulting in higher ratios on the writing-hand; furthermore, this could differ between left- and right-handers due to writing in the left-to-right direction (as in English) having asymmetrical effects depending on which hand is used.
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Affiliation(s)
- Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Centre for Research on Play in Education, Development & Learning, Faculty of Education, University of Cambridge, Cambridge, UK
| | - Sarah E Medland
- Psychiatric Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Psychology, University of Queensland, St Lucia, Australia.,School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Alan A Beaton
- Department of Psychology, School of Human & Health Sciences, Swansea University, Swansea, UK.,Department of Psychology, Aberystwyth University, Aberystwyth, UK
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7
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Richards G, Browne WV, Aydin E, Constantinescu M, Nave G, Kim MS, Watson SJ. Digit ratio (2D:4D) and congenital adrenal hyperplasia (CAH): Systematic literature review and meta-analysis. Horm Behav 2020; 126:104867. [PMID: 32998030 DOI: 10.1016/j.yhbeh.2020.104867] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 01/15/2023]
Abstract
The ratio of length between the second and fourth fingers (2D:4D) is commonly used as an indicator of prenatal sex hormone exposure. Several approaches have been used to try to validate the measure, including examining 2D:4D in people with congenital adrenal hyperplasia (CAH), a suite of conditions characterised by elevated adrenal androgen production secondary to defective steroidogenesis. We present a systematic review and meta-analysis that examines the relationship between these two variables. Twelve articles relating to nine CAH cohorts were identified, and 2D:4D comparisons have been made between cases and controls in eight of these cohorts. Altogether, at least one 2D:4D variable has been compared between n = 251 females with CAH and n = 358 unaffected females, and between n = 108 males with CAH and n = 204 unaffected males. A previous meta-analysis (Hönekopp and Watson, 2010) reported lower right hand (R2D:4D) and left hand (L2D:4D) digit ratios in patients with CAH relative to sex-matched controls. Our meta-analysis showed the same pattern, with medium effect sizes for R2D:4D and small effect sizes for L2D:4D. Differences of small magnitude were also observed for M2D:4D, and no significant effects were observed for D[R-L]. Notably, the only effects that remained statistically significant when stratified by sex were R2D:4D in males and L2D:4D in females, and the average effect size had reduced by 46.70% since the meta-analysis of Hönekopp and Watson (2010). We also found that individual comparisons in this literature were considerably underpowered, and that patterns of sexual dimorphism in 2D:4D were similar in CAH samples as in typically developing populations. Findings are discussed in relation to the prenatal androgen hypothesis as well as alternative explanations.
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Affiliation(s)
- Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK; Autism Research Centre, Department of Psychiatry, University of Cambridge, UK.
| | | | - Ezra Aydin
- Autism Research Centre, Department of Psychiatry, University of Cambridge, UK
| | - Mihaela Constantinescu
- Gender Development Research Centre, University of Cambridge, UK; School of Psychology, University of East London, UK
| | - Gideon Nave
- Marketing Department, The Wharton School, University of Pennsylvania, USA
| | - Mimi S Kim
- Keck School of Medicine, University of Southern California, USA
| | - Steven J Watson
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK; Department of Psychology of Conflict, Risk and Safety, University of Twente, Netherlands
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8
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Early environmental risk factors for neurodevelopmental disorders - a systematic review of twin and sibling studies. Dev Psychopathol 2020; 33:1448-1495. [PMID: 32703331 PMCID: PMC8564717 DOI: 10.1017/s0954579420000620] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
While neurodevelopmental disorders (NDDs) are highly heritable, several environmental risk factors have also been suggested. However, the role of familial confounding is unclear. To shed more light on this, we reviewed the evidence from twin and sibling studies. A systematic review was performed on case control and cohort studies including a twin or sibling within-pair comparison of neurodevelopmental outcomes, with environmental exposures until the sixth birthday. From 7,315 screened abstracts, 140 eligible articles were identified. After adjustment for familial confounding advanced paternal age, low birth weight, birth defects, and perinatal hypoxia and respiratory stress were associated with autism spectrum disorder (ASD), and low birth weight, gestational age and family income were associated with attention-deficit/hyperactivity disorder (ADHD), categorically and dimensionally. Several previously suspected factors, including pregnancy-related factors, were deemed due to familial confounding. Most studies were conducted in North America and Scandinavia, pointing to a global research bias. Moreover, most studies focused on ASD and ADHD. This genetically informed review showed evidence for a range of environmental factors of potential casual significance in NDDs, but also points to a critical need of more genetically informed studies of good quality in the quest of the environmental causes of NDDs.
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9
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Wernicke J, Zabel JT, Zhang Y, Becker B, Montag C. Association between tendencies for attention-deficit/hyperactivity disorder (ADHD) and the 2D:4D digit ratio: a cross-cultural replication in Germany and China. Early Hum Dev 2020; 143:104943. [PMID: 32126477 DOI: 10.1016/j.earlhumdev.2019.104943] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022]
Abstract
Prenatal testosterone is considered to be a possible factor contributing to the development of attention-deficit/hyperactivity disorder (ADHD) symptomatology, but findings regarding the connection between individual variations in prenatal testosterone exposure as (indirectly) indexed by the second-to-fourth digit (2D:4D) ratio and ADHD remain inconsistent. To clarify the inconsistent findings and to facilitate generalization on the association between subclinical variations in ADHD tendencies and lower 2D:4D ratios the current study applied a cross-cultural replication approach employing independent healthy adult cohorts from Germany and China. Samples from Germany and China were matched for gender and age (in each sample nmales = 96, nfemales = 96; ageGermany: M = 21.47, SD = 2.55; ageChina: M = 21.36, SD = 2.28). All participants filled in the Adult ADHD Self-Report Scale Symptom Checklist (ASRS) and provided hand scans to measure 2D:4D ratios. The German sample had significantly higher 2D:4D ratios than the Chinese sample but in both samples males had significantly lower 2D:4D ratios than females. The hypothesised negative association between 2D:4D ratios and ADHD tendencies was observed on a descriptive level in German and Chinese males and with one exception in Chinese females. But only in German males correlations gained significance (range: r = -0.198 to r = -0.177). The observed effect sizes are in line with former research that was conducted in samples from different cultures. In future research on the connection between testosterone and ADHD not only prenatal but also postnatal testosterone as well as possible moderators like childhood maltreatment should be taken into account.
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Affiliation(s)
- Jennifer Wernicke
- Department of Molecular Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany.
| | - Julia Tamara Zabel
- Department of Molecular Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany
| | - Yingying Zhang
- Department of Molecular Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany
| | - Benjamin Becker
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Laboratory for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
| | - Christian Montag
- Department of Molecular Psychology, Institute of Psychology and Education, Ulm University, Ulm, Germany; The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Laboratory for Neuroinformation, University of Electronic Science and Technology of China, Chengdu, China
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10
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Myers L, Anderlid BM, Nordgren A, Lundin K, Kuja-Halkola R, Tammimies K, Bölte S. Clinical versus automated assessments of morphological variants in twins with and without neurodevelopmental disorders. Am J Med Genet A 2020; 182:1177-1189. [PMID: 32162839 DOI: 10.1002/ajmg.a.61545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 12/05/2019] [Accepted: 02/14/2020] [Indexed: 12/28/2022]
Abstract
Physical examinations are recommended as part of a comprehensive evaluation for individuals with neurodevelopmental disorders (NDDs), such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder. These examinations should include assessment for morphological variants. Previous studies have shown an increase in morphological variants in individuals with NDDs, particularly ASD, and that these variants may be present in greater amounts in individuals with genetic alterations. Unfortunately, assessment for morphological variants can be subjective and time-consuming, and require a high degree of clinical expertise. Therefore, objective, automated methods of morphological assessment are desirable. This study compared the use of Face2Gene, an automated tool to explore facial morphological variants, to clinical consensus assessment, using a cohort of N = 290 twins enriched for NDDs (n = 135 with NDD diagnoses). Agreement between automated and clinical assessments were satisfactory to complete (78.3-100%). In our twin sample, individuals with NDDs did not have greater numbers of facial morphological variants when compared to those with typical development, nor when controlling for shared genetic and environmental factors within twin pairs. Common facial morphological variants in those with and without NDDs were similar and included thick upper lip vermilion, abnormality of the nasal tip, long face, and upslanted palpebral fissure. We conclude that although facial morphological variants can be assessed reliably in NDDs with automated tools like Face2Gene, clinical utility is limited when just exploring the facial region. Therefore, currently, automated assessments may best complement, rather than replace, in-person clinical assessments.
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Affiliation(s)
- Lynnea Myers
- Center of Neurodevelopmental Disorders (KIND), Division of Neuropsychiatry, Centre for Psychiatry Research; Department of Women's and Children's Health, Karolinska Institutet, Stockholm Health Care Services, Stockholm, Sweden
| | - Britt-Marie Anderlid
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Ann Nordgren
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Karl Lundin
- Center of Neurodevelopmental Disorders (KIND), Division of Neuropsychiatry, Centre for Psychiatry Research; Department of Women's and Children's Health, Karolinska Institutet, Stockholm Health Care Services, Stockholm, Sweden
| | - Ralf Kuja-Halkola
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Kristiina Tammimies
- Center of Neurodevelopmental Disorders (KIND), Division of Neuropsychiatry, Centre for Psychiatry Research; Department of Women's and Children's Health, Karolinska Institutet, Stockholm Health Care Services, Stockholm, Sweden
| | - Sven Bölte
- Center of Neurodevelopmental Disorders (KIND), Division of Neuropsychiatry, Centre for Psychiatry Research; Department of Women's and Children's Health, Karolinska Institutet, Stockholm Health Care Services, Stockholm, Sweden.,Child and Adolescent Psychiatry, Stockholm Health Care Services, Stockholm, Sweden.,Curtin Autism Research Group, School of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, Western Australia
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Bölte S, Girdler S, Marschik PB. The contribution of environmental exposure to the etiology of autism spectrum disorder. Cell Mol Life Sci 2019; 76:1275-1297. [PMID: 30570672 PMCID: PMC6420889 DOI: 10.1007/s00018-018-2988-4] [Citation(s) in RCA: 261] [Impact Index Per Article: 52.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/14/2018] [Accepted: 12/04/2018] [Indexed: 01/04/2023]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental condition of heterogeneous etiology. While it is widely recognized that genetic and environmental factors and their interactions contribute to autism phenotypes, their precise causal mechanisms remain poorly understood. This article reviews our current understanding of environmental risk factors of ASD and their presumed adverse physiological mechanisms. It comprehensively maps the significance of parental age, teratogenic compounds, perinatal risks, medication, smoking and alcohol use, nutrition, vaccination, toxic exposures, as well as the role of extreme psychosocial factors. Further, we consider the role of potential protective factors such as folate and fatty acid intake. Evidence indicates an increased offspring vulnerability to ASD through advanced maternal and paternal age, valproate intake, toxic chemical exposure, maternal diabetes, enhanced steroidogenic activity, immune activation, and possibly altered zinc-copper cycles and treatment with selective serotonin reuptake inhibitors. Epidemiological studies demonstrate no evidence for vaccination posing an autism risk. It is concluded that future research needs to consider categorical autism, broader autism phenotypes, as well as autistic traits, and examine more homogenous autism variants by subgroup stratification. Our understanding of autism etiology could be advanced by research aimed at disentangling the causal and non-causal environmental effects, both founding and moderating, and gene-environment interplay using twin studies, longitudinal and experimental designs. The specificity of many environmental risks for ASD remains unknown and control of multiple confounders has been limited. Further understanding of the critical windows of neurodevelopmental vulnerability and investigating the fit of multiple hit and cumulative risk models are likely promising approaches in enhancing the understanding of role of environmental factors in the etiology of ASD.
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Affiliation(s)
- Sven Bölte
- Department of Women's and Children's Health, Karolinska Institutet & Child and Adolescent Psychiatry, Stockholm Health Care Services, Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Stockholm County Council, Stockholm, Sweden.
- Curtin Autism Research Group, School of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, WA, Australia.
| | - Sonya Girdler
- Curtin Autism Research Group, School of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, WA, Australia
| | - Peter B Marschik
- Department of Women's and Children's Health, Karolinska Institutet & Child and Adolescent Psychiatry, Stockholm Health Care Services, Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Stockholm County Council, Stockholm, Sweden
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Medical Center Göttingen, Göttingen, Germany
- iDN-interdisciplinary Developmental Neuroscience, Department of Phoniatrics, Medical University of Graz, Graz, Austria
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