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Biologie de l'intelligence

- Une étude sur 256 jumeaux monozygotes et 326 jumeaux dizygotes confirme la forte héritabilité de l'intelligence chez l'adolescente et le jeune adulte (15-22 ans) : 0.76 (ce qui signifie que 76% des différences entre individus s'expliquent par les gènes, les 24% restant par le milieu partagé ou non partagé).

- Une étude menée sur 3044 individus (âge moyen 18,7 ans) confirme la corrélation négative entre QI adulte et consommation de tabac par la mère durant le premier trimestre de la grossesse (ajustement avec des facteurs covariants comme le statut socio-économique). La différence entre enfants de non-fumeurs et de gros fumeurs atteint 6,2 points de QI.

- Une étude menée sur 35 sujets âgés et 39 sujets de contrôle montre que le volume global du cerveau, le volume de la matière grise et le volume de la matière grise sont négativement corrélés au déclin cognitif associé à l'âge chez le sujet normal.

- Une étude menée sur 55 sujets n'a constaté aucun effet de l'usage intensif du téléphone mobile sur le QI (durée de l'expérience : 45 jours).

Bref : Votre grand-père a fait des mots croisés jusqu'à 107 ans ? Votre mère était non fumeuse ? Votre frère jumeau a un QI de 186 ? Vous pouvez appeler tous vos amis pour leur dire que vous êtes bien parti dans la vie…

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Behavior Genetics

DOI: 10.1007/s10519-004-1014-9

Issue: Volume 35, Number 2

Date:  March 2005

Pages: 133 - 145

The Genetic Basis of Academic Achievement on the Queensland Core Skills Test and its Shared Genetic Variance with IQ

Mark A. Wainwright1, 2, 3 Margaret J. Wright1, Gina M. Geffen2, Michelle Luciano1 and Nicholas G. Martin1

(1) Queensland Institute of Medical Research, Brisbane, Australia

(2) Cognitive Psychophysiology Laboratory, School of Psychology, University of Queensland, Brisbane, Australia

(3) Queensland Institute of Medical Research, Post Office Royal Brisbane Hospital, Herston, Brisbane, QLD, 4029, Australia

Received: 21 June 2004  Accepted: 28 September 2004 

Abstract  First, this study examined genetic and environmental sources of variation in performance on a standardised test of academic achievement, the Queensland Core Skills Test (QCST) (Queensland Studies Authority, 2003a). Second, it assessed the genetic correlation among the QCST score and Verbal and Performance IQ measures using the Multidimensional Aptitude Battery (MAB), [Jackson, D. N. (1984) Multidimensional Aptitude Battery manual. Port Huron, MI:Research Psychologist Press, Inc.]. Participants were 256 monozygotic twin pairs and 326 dizygotic twin pairs aged from 15 to 18 years (mean 17 years ± 0.4 [sD]) when achievement tested, and from 15 to 22 years (mean 16 years ± 0.4 [sD]) when IQ tested. Univariate analysis indicated a heritability for the QCST of 0.72. Adjustment to this estimate due to truncate selection (downward adjustment) and positive phenotypic assortative mating (upward adjustment) suggested a heritability of 0.76 The phenotypic (0.81) and genetic (0.91) correlations between the QCST and Verbal IQ (VIQ) were significantly stronger than the phenotypic (0.57) and genetic (0.64) correlations between the QCST and Performance IQ (PIQ). The findings suggest that individual variation in QCST performance is largely due to genetic factors and that common environmental effects may be substantially accounted for by phenotypic assortative mating. Covariance between academic achievement on the QCST and psychometric IQ (particularly VIQ) is to a large extent due to common genetic influences.

Keywords  Academic - achievement - heritability - intelligence - twins

**

Paediatr Perinat Epidemiol. 2005 Jan;19(1):4-11.

A dose-response relationship between maternal smoking during late pregnancy and adult intelligence in male offspring.

Mortensen EL, Michaelsen KF, Sanders SA, Reinisch JM.

Danish Epidemiology Science Centre, Institute of Preventive Medicine, Copenhagen University Hospital, Copenhagen, Denmark.

Summary An association between maternal smoking during pregnancy and cognitive and behavioural development has been observed in several studies, but potential effects of maternal smoking on offspring adult intelligence have not been investigated. The objective of the present study was to investigate a potential association between maternal smoking during pregnancy and offspring intelligence in young adulthood. Adult intelligence was assessed at the mean age of 18.7 years by a military draft board intelligence test (Borge Priens Prove) for 3044 singleton males from the Copenhagen Perinatal Cohort with information regarding maternal smoking during the third trimester coded into five categories (about 50% of the mothers were smokers). The following potential confounders were included as covariates in multivariable analyses: parental social status and education, single mother status, mother's height and age, number of pregnancies, and gestational age. In separate analyses, birthweight and length were also included as covariates. Maternal cigarette smoking during the third trimester, adjusted for the seven covariates, showed a negative association with offspring adult intelligence (P = 0.0001). The mean difference between the no-smoking and the heaviest smoking category amounted to 0.41 standard deviation, corresponding to an IQ difference of 6.2 points [95% confidence interval 0.14, 0.68]. The association remained significant when further adjusted for birthweight and length (P = 0.007). Both unadjusted and adjusted means suggested a dose-response relationship between maternal smoking during pregnancy and offspring adult intelligence. When subjects with missing data were excluded, essentially the same results were obtained in the reduced sample (n = 1829). These results suggest that smoking during pregnancy may have long-term negative consequences on offspring adult intelligence.

PMID: 15670102 [PubMed - in process]

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Dement Geriatr Cogn Disord. 2005 Jan 25;19(4):213-221 [Epub ahead of print]

Association between Global Brain Volume and the Rate of Cognitive Change in Elderly Humans without Dementia.

Hensel A, Wolf H, Kruggel F, Busse A, Arendt T, Gertz HJ.

Karolinska Institute, Neurotec, Division of Clinical Geriatrics, Huddinge University Hospital, Stockholm, Sweden.

Patients with mild cognitive deficits experience different types of evolution. They are at increased risk of developing dementia, but they have also a chance of remaining stable in cognition or of improving. We investigated whether global brain volume, callosal size and hippocampal size are associated with the rate of cognitive change in elderly without dementia. Volumetric MR images were recorded from 39 controls and 35 patients with questionable dementia who were followed up longitudinally for a mean of 2.3 years. The outcome measure was the annual change in the test score in the Structured Interview for the Diagnosis of Alzheimer's Dementia and Multi-Infarct Dementia, which includes all items of the Mini-Mental State Examination. Global brain volume, grey matter volume and white matter volume were the only significant independent predictors of the rate of cognitive change.

**

Bioelectromagnetics. 2005 Feb;26(2):102-8.

Related Articles,  Links

No effect on cognitive function from daily mobile phone use.

Besset A, Espa F, Dauvilliers Y, Billiard M, de Seze R.

Institut National de la Sante et de la Recherche Medicale, E 0361 Montpellier, France.

The increasing use of mobiles phones (MP) has raised the problem of the effects of daily electromagnetic fields (EMF) exposure on human health. To date several studies have been published concerning the effects of acute MP exposure on psychomotor performances. This study investigated the effects of daily exposure to GSM 900 type MP on cognitive function. Fifty-five subjects (27 male and 28 female) were divided into two groups: a group with MP switched on and a group with MP switched off. The two groups were matched according to age, gender, and IQ. This double blind study lasted for 45 days and was divided in three periods: baseline (BLP, 2 days), exposure (EP, 27 days), and recovery (RP, 13 days). Subjects were exposed during EP and sham exposed during RP for 2 h/day, 5 days/week. The neuropsychological test battery composed of 22 tasks screened four neuropsychological categories: information processing, attention capacity, memory function, and executive function. This neuropsychological battery was performed four times on day 2 (BLP), day 15 (EP), day 29 (EP), and day 43 (RP). Our results indicate that daily MP use has no effect on cognitive function after a 13-h rest period. Bioelectromagnetics 26:102-108, 2005. © 2005 Wiley-Liss, Inc.

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