Higher Intelligence Quotient Scores Research Articles

An Overview of Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports (12th ed.).

An Overview of Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports (12th ed.).

Child physical activity as a modifier of the relationship between prenatal exposure to maternal overweight/obesity and neurocognitive outcomes in offspring.

Background/Objectives:With rising obesity rates among pregnant women, more children are exposed in utero to maternal obesity. In prior epidemiological studies, exposure to maternal obesity was associated with lower intelligence quotient (IQ) scores and worse cognitive abilities in offspring. Further studies have shown that offspring exposed to maternal obesity, exhibit differences in the white matter microstructure properties, fractional anisotropy (FA) and mean diffusivity (MD). In contrast, physical activity was shown to improve cognition and white matter microstructure during childhood. We examined if child physical activity levels modify the relationship between prenatal exposure to maternal obesity with IQ and white matter microstructure in offspring.Subjects/Methods:One hundred children (59% girls) age 7–11 years underwent brain magnetic resonance imaging and IQ testing. Maternal pre-pregnancy BMI was abstracted from electronic medical records. White matter was assessed using diffusion tensor imaging with the measures, global FA, MD. The 3-day physical activity recall was used to measure moderate-to-vigorous physical activity and vigorous physical activity (VPA). Linear regression was used to test for interactions between prenatal exposure to maternal overweight/obesity and child PA levels on child IQ and global FA/MD.Results:The relationship between prenatal exposure to maternal overweight/obesity and child IQ and global FA varied by child VPA levels. Children exposed to mothers with overweight/obesity who engaged in more VPA had higher IQ scores and global FA compared to exposed children who engaged in less VPA. Associations were independent of child age, sex, BMI Z-score and socioeconomic status. Children born to normal-weight mothers did not differ in either IQ or global FA by time in VPA.Conclusions:Our findings support findings in rodent models and suggest that VPA during childhood modifies the relationship between prenatal exposure to maternal obesity and child IQ and white matter microstructure.

Naturalistic evaluation of preschoolers' spontaneous interactions: The Autism Peer Interaction Observation Scale.

Peer interaction can be challenging in autism spectrum disorder, but naturalistic peer-observation scales for preschoolers are scarce. This study examined psychometric qualities of the newly developed Autism Peer Interaction Observation Scale. We tested the Autism Peer Interaction Observation Scale to (a) characterize peer interactions of preschoolers with autism spectrum disorder who were cognitively able versus typical age-mates, (b) explore each group’s hierarchical pattern of peer interaction behaviors, and (c) identify Autism Peer Interaction Observation Scale’s links with standard reports for assessing social-communication functioning (Vineland Behavior Scales, 2nd ed.), social impairment (Social Responsiveness Scale, 2nd ed.), autism severity (Autism Diagnostic Observation Schedule, 2nd ed.), and intelligence quotient (Mullen) in the cognitively able preschoolers with autism spectrum disorder group. Participants comprised 85 preschoolers (50 cognitively able preschoolers with autism spectrum disorder, intelligence quotient > 75; 35 typical). Groups were matched for age, intelligence quotient, and maternal education. Significant group differences emerged on all Autism Peer Interaction Observation Scale categories, in favor of typical. In cognitively able preschoolers with autism spectrum disorder, correlation analyses indicated that more typical peer relations on Autism Peer Interaction Observation Scale were linked with better adaptive and socialization skills (Vineland Behavior Scales, 2nd ed.) and fewer social atypicalities (Social Responsiveness Scale, 2nd ed.). Higher intelligence quotient scores were linked with better Autism Peer Interaction Observation Scale social-communication functioning. Only a few Autism Peer Interaction Observation Scale social-communication categories significantly correlated with the Autism Diagnostic Observation Schedule, 2nd ed. Findings highlight the Autism Peer Interaction Observation Scale as differentiating between groups and providing knowledge about peer interaction in natural settings. This new tool can help personalize social-communication programs and evaluations of early intervention outcomes.Lay abstractPeer interaction can be challenging in autism spectrum disorder, but naturalistic peer-observation scales for preschoolers are limited. This study examined the newly developed Autism Peer Interaction Observation Scale, with 17 subcategories, which evaluate naturalistic peer interaction processes in preschoolers with autism spectrum disorder and typical development. We tested the Autism Peer Interaction Observation Scale to (a) characterize peer interactions of preschoolers with autism spectrum disorder who were cognitively able versus typical age-mates, (b) explore each group’s hierarchical pattern of peer interaction behaviors, and (c) identify Autism Peer Interaction Observation Scale’s links with standard reports for assessing social-communication functioning (Vineland Behavior Scales, 2nd ed.), social impairment (Social Responsiveness Scale, 2nd ed.), autism severity (Autism Diagnostic Observation Schedule, 2nd ed.), and intelligence quotient (Mullen) in the cognitively able preschoolers with autism spectrum disorder group. Participants comprised 85 preschoolers (50 cognitively able preschoolers with autism spectrum disorder, intelligence quotient > 75; 35 typical). Groups were matched according to age, intelligence quotient, and maternal education. Significant group differences emerged on all Autism Peer Interaction Observation Scale categories, with the typical group showing better social-communication functioning as compared to the cognitively able preschoolers with autism spectrum disorder group. Also, in cognitively able preschoolers with autism spectrum disorder that observed as demonstrating more typical peer relations on the Autism Peer Interaction Observation Scale showed better adaptive and socialization skills on the Vineland (Vineland Behavior Scales, 2nd ed.) and fewer social atypicalities on the Social Responsiveness Scale, 2nd ed. Higher intelligence quotient scores were linked with better observed social-communication functioning (on Autism Peer Interaction Observation Scale). Few Autism Peer Interaction Observation Scale social-communicative categories significantly correlated with the Autism Diagnostic Observation Schedule, 2nd ed. Findings highlight the Autism Peer Interaction Observation Scale as differentiating the two preschooler groups and providing additional knowledge about socially communicative peer interaction in natural settings. This new tool can help personalize social-communication programs and evaluations of early intervention outcomes, thereby leading to a fuller picture of these young children’s functioning.

How do children and youth with autism spectrum disorder self-report on behavior? A study of the validity indexes on the Behavior Assessment System for Children, Second Edition, self-report of personality.

Using self-report questionnaires is an important method in the assessment and treatment of children with autism. Self-reports can provide unique information about children's feelings and thoughts that is not available through other methods such as parent-reports. However, many clinicians are not sure whether children with autism can provide accurate self-reports. To study this, we examined 139 children and youth with and without autism aged 8-17 years. We looked at the effect of having autism, as well as other factors such as age, intelligence quotient, and attention problems on the validity of self-reports in these children. We examined if the children gave overly negative or positive answers and if they responded to the questions randomly or without paying attention. We found that children with autism can provide acceptable self-reports. However, they have more validity problems compared to their peers without autism. Our findings showed that this difference might be related to having attention problems in addition to autism, rather than having autism by itself. Children, with and without autism spectrum disorder, with fewer attention problems and higher intelligence quotient scores and those in the older age group, showed better validity. This article suggests that clinicians can use self-report measures for children with autism, but they should pay attention to important factors such as children's intelligence quotient and attention problems.

190-OR: Impact of Prenatal Exposure to Maternal Obesity and Child Physical Activity Levels on Neurocognition

Prenatal exposure to maternal obesity is linked to neurocognitive deficits in offspring. In contrast, engaging in physical activity (PA) is beneficial for cognition and brain development. We aimed to determine if greater PA is associated with higher intelligence quotient (IQ) scores and greater brain white matter integrity in children born to mothers with a range of pre-pregnancy BMI. Ninety-nine children (59 girls) ages 7-13 years completed the study. Maternal pre-pregnancy BMI was obtained from electronic medical records. Wechsler Abbreviated Scale of Intelligence was used to measure IQ. Diffusion tensor imaging was used to measure mean global fractional anisotropy (FA), a marker of white matter integrity. Time spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) was assessed using 3-day PA recalls. Linear regressions were used to assess whether maternal pre-pregnancy BMI or child MVPA and VPA were associated with child IQ scores and global FA. Maternal pre-pregnancy BMI ranged from 19.0-54.0 kg/m2 (43% obese). Mean±SD child IQ was 106.4±14.0, MVPA was 132.8±95.4 min/day, and VPA was 19.0±27.1 min/day. Maternal pre-pregnancy BMI was negatively associated with child IQ scores (β=-0.31; p=0.10); this marginal association remained after adjusting for child age, sex, puberty, BMI z-score, and socioeconomic status (β=-0.42; p=0.095). MVPA was not associated with child IQ (β=2.63; p=0.16). However, children who spent more time in VPA had higher IQ scores before (β=7.05; p=0.003) and after adjusting for the same co-variates (β=5.65; p=0.024) and further adjusting for maternal pre-pregnancy BMI (β=5.01; p=0.049). Children who spent more time in VPA also had greater mean global FA (unadjusted: β=0.01; p=0.017; adjusted: β=0.01; p=0.005). These findings suggest that engaging in VPA is beneficial for cognition and white matter microstructure in children, independent of maternal pre-pregnancy BMI. Disclosure J. Alves: None. B.C. Angelo: None. S.H. Luo: None. T. Chow: None. A.G. Yunker: None. A. Xiang: None. K.A. Page: None. J. Zink: None. B.R. Belcher: None. K. Clark: None. Funding American Diabetes Association (1-14-ACE-36 to K.A.P.); National Institute of Diabetes and Digestive and Kidney Diseases (R01DK116858); National Institute of Mental Health (F31MH115640)

Intelligence of Hearing-Impaired Children: An Evaluation Based on Demographic, Educational, and Audiological Characteristics

Studies to determine the intelligence level of children with special needs are performed by Guidance and Research Centers, university research centers, schools, and the relevant clinics of hospitals for a variety of reasons. International occupational organizations describe that gaining an understanding of the intelligence characteristics of hearing-impaired children in different cultures and societies is of critical importance to ensure that specialists and researchers performing intelligence tests can interpret their results correctly. Based on this consideration, the purpose of this study was to demonstrate the intelligence characteristics of hearing-impaired children through comparisons with children with typical development. In addition, I investigated the relationship of the intelligence quotient (IQ) score with basic demographic, educational, and audiological variables, and evaluated whether IQ scores differed according to these variables. The sample of the study consisted of 329 hearing-impaired children in different educational settings within the Eskisehir province. According to the results of the one sample t-test performed within the frame of the study’s main purpose, the total IQ scores of the hearing-impaired children, as determined by the WISC-R performance sub-tests, were higher than the scores of the standardization sample of Turkey. Pearson correlation analysis indicated that the WISC-R performance sub-tests had a moderate correlation with one another, and a high correlation with IQ scores. Among the different demographic variables, the educational level of both the father and mother had a significant effect on total IQ scores, although the fathers’ level of education showed a higher correlation with total IQ than the mothers’. In regards to the audiological variables, the degree of hearing loss did not have a significant correlation with total IQ. Based on the ANCOVA, in which the fathers’ level of education as covariate, it was determined that with respect to the gender, male children had higher total IQ scores than female children; and that, with respect to the educational setting variable, children receiving education at the Education and Research Center for Hearing Impaired Children (ICEM) and in inclusive settings had higher total IQ scores than children receiving education at the Ministry of National Education’s (MoNE) Elementary Schools for the Hearing Impaired. No significant difference was identified in terms of IQ scores between children using hearing aids and children using cochlear implants. Higher IQ scores were observed for the standardization group during the comparison of Turkey’s standardization sample with the hearing-impaired children sample. We believe that this may have been due to the fact that the test’s standardization data were somewhat not actual. The study findings indicate that individuals performing intelligence assessments on hearing-impaired children should take into account the socio-economic level of these children’s families, as well as the educational setting. Possible recommendations we can make to other researchers include determining the psychometric characteristics of the new version of this test and other non-verbal intelligence tests; conducting norm studies; testing the psychometric characteristics of intelligence tests with groups that have different special needs; and developing tests suitable for the Turkish culture.

Brain Imaging and Neurodevelopment in HIV-uninfected Thai Children Born to HIV-infected Mothers.

Perinatal use of combination antiretroviral therapy dramatically reduces vertical (mother-to-child) transmission of HIV but has led to a growing population of children with perinatal HIV-exposure but uninfected (HEU). HIV can cause neurological injury among children born with infection, but the neuroanatomical and developmental effects in HEU children are poorly understood. We used structural magnetic resonance imaging with diffusion tensor imaging to compare brain anatomy between 30 HEU and 33 age-matched HIV-unexposed and uninfected (HUU) children from Thailand. Maps of brain volume and microstructural anatomy were compared across groups; associations were tested between neuroimaging measures and concurrent neuropsychological test performance. Mean (standard deviation) age of children was 10.3 (2.8) years, and 58% were male. All were enrolled in school and lived with family members. Intelligence quotient (IQ) did not differ between groups. Caretaker education levels did not differ, but income was higher for HUU (P < 0.001). We did not detect group differences in brain volume or diffusion tensor imaging metrics, after controlling for sociodemographic factors. The mean (95% confidence interval) fractional anisotropy in the corpus callosum was 0.375 (0.368-0.381) in HEU compared with 0.370 (0.364-0.375) in HUU. Higher fractional anisotropy and lower mean diffusivity were each associated with higher IQ scores in analyses with both groups combined. No differences in neuroanatomical or brain integrity measures were detectable in HEU children compared with age-matched and sex-matched controls (HUU children). Expected associations between brain integrity measures and IQ scores were identified suggesting sufficient power to detect subtle associations that were present.

Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil.

SummaryBackgroundBreastfeeding has clear short-term benefits, but its long-term consequences on human capital are yet to be established. We aimed to assess whether breastfeeding duration was associated with intelligence quotient (IQ), years of schooling, and income at the age of 30 years, in a setting where no strong social patterning of breastfeeding exists.MethodsA prospective, population-based birth cohort study of neonates was launched in 1982 in Pelotas, Brazil. Information about breastfeeding was recorded in early childhood. At 30 years of age, we studied the IQ (Wechsler Adult Intelligence Scale, 3rd version), educational attainment, and income of the participants. For the analyses, we used multiple linear regression with adjustment for ten confounding variables and the G-formula.FindingsFrom June 4, 2012, to Feb 28, 2013, of the 5914 neonates enrolled, information about IQ and breastfeeding duration was available for 3493 participants. In the crude and adjusted analyses, the durations of total breastfeeding and predominant breastfeeding (breastfeeding as the main form of nutrition with some other foods) were positively associated with IQ, educational attainment, and income. We identified dose-response associations with breastfeeding duration for IQ and educational attainment. In the confounder-adjusted analysis, participants who were breastfed for 12 months or more had higher IQ scores (difference of 3·76 points, 95% CI 2·20–5·33), more years of education (0·91 years, 0·42–1·40), and higher monthly incomes (341·0 Brazilian reals, 93·8–588·3) than did those who were breastfed for less than 1 month. The results of our mediation analysis suggested that IQ was responsible for 72% of the effect on income.InterpretationBreastfeeding is associated with improved performance in intelligence tests 30 years later, and might have an important effect in real life, by increasing educational attainment and income in adulthood.FundingWellcome Trust, International Development Research Center (Canada), CNPq, FAPERGS, and the Brazilian Ministry of Health.

The Association of High Birth Weight With Intelligence in Young Adulthood

We aimed to explore why, in population studies, the positive association between normal-range birth weight and intelligence becomes negative at the highest birth weights. The study population comprised 217,746 Norwegian male singletons born at term between 1967 and 1976. All had data on birth weight and intelligence quotient (IQ) score at the time of military conscription; 137,574 had data on sibling birth weights; and 62,906 had data on male sibling birth weights. We estimated associations between birth weight and IQ score by ordinary least squares regression for the total study population and by fixed-effects regression for comparisons of brothers. The crude mean IQ score was 1.2 points (95% confidence interval (CI): 0.3, 2.2) lower for those with birth weights of 5,000 g or more compared with the reference group (with birth weights of 4,000-4,499 g). This difference leveled off to 0.0 (95% CI: -0.8, 0.9) in multivariable ordinary least squares regression and reversed to 2.2 points (95% CI: 0.3, 4.2) higher in fixed-effects regression. Results differed mainly because, at a given birth weight, participants who had a sibling with macrosomia had a lower mean IQ score. Nevertheless, within families with 1 or more macrosomic siblings, as in other families, men with higher birth weights tended to have higher IQ scores. Thus, a family-level confounder introduces a cross-level bias that cannot be detected in individual-level studies. We suggest ways in which future studies might elucidate the nature of this confounder.

The association of high birth weight with intelligence in young adulthood: a cohort study of male siblings.

We aimed to explore why, in population studies, the positive association between normal-range birth weight and intelligence becomes negative at the highest birth weights. The study population comprised 217,746 Norwegian male singletons born at term between 1967 and 1976. All had data on birth weight and intelligence quotient (IQ) score at the time of military conscription; 137,574 had data on sibling birth weights; and 62,906 had data on male sibling birth weights. We estimated associations between birth weight and IQ score by ordinary least squares regression for the total study population and by fixed-effects regression for comparisons of brothers. The crude mean IQ score was 1.2 points (95% confidence interval (CI): 0.3, 2.2) lower for those with birth weights of 5,000 g or more compared with the reference group (with birth weights of 4,000-4,499 g). This difference leveled off to 0.0 (95% CI: -0.8, 0.9) in multivariable ordinary least squares regression and reversed to 2.2 points (95% CI: 0.3, 4.2) higher in fixed-effects regression. Results differed mainly because, at a given birth weight, participants who had a sibling with macrosomia had a lower mean IQ score. Nevertheless, within families with 1 or more macrosomic siblings, as in other families, men with higher birth weights tended to have higher IQ scores. Thus, a family-level confounder introduces a cross-level bias that cannot be detected in individual-level studies. We suggest ways in which future studies might elucidate the nature of this confounder.

Association between Genetic Polymorphism rs2952768, Close to the METTL21A and CREB1 Genes, and Intellectual Ability in Healthy Subjects

Objective: Human intelligence, which represents a set of cognitive abilities, is assumed to be a highly heterogenic trait. The Intelligence Quotient (IQ) is the most widely used index for characterizing human intelligence in psychometric studies, and knowledge of the genes associated with IQ has continuously grown. Several previous reports indicated that IQ may be associated with addictive behaviors or the use of addictive substances, although the trend toward an association is not straightforward and depends on the substances abused. To explore the genetic factors that contribute to IQ, we conducted an association study of a genetic polymorphism, rs2952768. The rs2952768 single-nucleotide polymorphism (SNP) was recently reported to be associated with human opioid sensitivity and shown to be associated with the efficacy of opioid analgesics, severity of substance dependence, and mRNA expression levels of a neighboring gene, CREB1. Methods: The present study used data from 298 biologically unrelated Japanese subjects. Psychiatrically, medically, and neurologically healthy subjects were evaluated using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Non-Patient Edition (SCID-I/NP), to exclude individuals who had substance-related disorders, who had received psychiatric medications, or who had first- or second-degree relatives with psychiatric disorders. Genotyping was performed using the Affymetrix Genome-Wide Human SNP Array 6.0. The rs2952768 SNP close to the METTL21A gene was extracted from this dataset. Multiple linear regression analysis was performed to compare intellectual ability among rs2952768 SNP genotypes. Results: A significant effect of the SNP genotype was observed on current IQ (β = -2.27, p = 0.026). The number of non-risk major C allele for drug and alcohol dependence was correlated with higher IQ scores. Conclusion: The present results suggest that the rs2952768 SNP, which was identified as a potent SNP associated with human opioid sensitivity, is also one of the genetic factors that contribute to human intellectual ability.

Psychiatric profile of physically ill pediatric patients

Background Mental health is an important component of overall health and mental disorders that can cause suffering, disability, and, rarely, even death. Pediatric-psychiatric liaison programs have evolved to enable the staff pediatricians to receive adequate training to assess emotional, behavioral, and family problems that may be an integral part of the patient's symptoms. Objectives The aim of the current study is to assess the prevalence of psychiatric symptoms among physically ill children ranging in age from 16 to 18 years attending the pediatric outpatient clinic in Beni Suef University Hospital and to compare the differences in psychiatric symptoms in relation to sex and the nature of physical illness among these patients. Participants and methods This survey study is a cross-sectional, observational, and comparative study. The study was carried out in the Pediatric outpatient clinic of Beni Suef University Hospital. A random sample of 300 Egyptian children with acute and chronic illness aged between 6 and 18 years, fulfilling the inclusion and exclusion criteria, participated in this study over an 8-month duration starting from May 2011 to December 2011. All participants of the study, both patients and informants, were subjected to a screening test using 'the Child Behavior Checklist for ages 6-18,' and intelligence quotient (IQ) was assessed for all sharing patients using the 'Stanford-Binet Intelligence Scale.' Results One hundred and seventy (56.7%) of the 300 selected patients were females and 130 (43.3%) were males; 260 of these patients attended regular schools. Out of the total number of patients, 155 (51.67%) presented with acute illness, whereas 145 (48.33%) had chronic illnesses. The mean IQ score was 79.8 ± 15.2 and only 22.3% of the sample (67 patients) had an 'average' IQ. Sex-based comparison of IQ results showed that female patients had significantly higher IQ scores (82.2 ± 13.6 with P = 0.035). However, Child Behavior Checklist 6-18 scores showed that 223 out of 300 patients had diagnosable Internalizing disorders with internalizing T -scores above 70; 118 (52.9%) of these were females compared with 105(47.1%) males, with a statistically significant difference ( P = 0.026). Meanwhile, 203 patients had diagnosable externalizing disorders with externalizing T -scores above 70; 104 (51.2%) of these were females. IQ scores differed significantly, being higher in acute illnesses (82.3 ± 13.6 vs. 77.8 ± 15.9 and P = 0.025). Another significant difference between patients with acute illnesses and those with chronic illnesses was clear in the internalizing T -score and the externalizing T- score (higher in acute illnesses, P = 0.028 and 0.034, respectively). Conclusion The current status of psychiatric problems in pediatric physically ill patients calls for mandatory cooperation in pediatric consultation-liaison services in the Beni Suef Governorate.

Dietary patterns at 6, 15 and 24 months of age are associated with IQ at 8 years of age

Diet supplies the nutrients needed for the development of neural tissues that occurs over the first 2 years of life. Our aim was to examine associations between dietary patterns at 6, 15 and 24 months and intelligence quotient (IQ) scores at 8 years. Participants were enrolled in an observational birth cohort (ALSPAC study, n = 7,097). Dietary data was collected by questionnaire and patterns were extracted at each time using principal component analysis. IQ was measured using the Wechsler Intelligence Scale for Children at 8 years. Associations between dietary patterns and IQ were examined in regression analyses adjusted for potential confounding and by propensity score matching, with data imputation for missing values. At all ages, higher scores on a Discretionary pattern (characterized by biscuits, chocolate, sweets, soda, crisps) were associated with 1-2 point lower IQ. A Breastfeeding pattern at 6 months and Home-made contemporary patterns at 15 and 24 months (herbs, legumes, cheese, raw fruit and vegetables) were associated with 1-to-2 point higher IQ. A Home-made traditional pattern (meat, cooked vegetables, desserts) at 6 months was positively associated with higher IQ scores, but there was no association with similar patterns at 15 or 24 months. Negative associations were found with patterns characterized by Ready-prepared baby foods at 6 and 15 months and positive associations with a Ready-to-eat foods pattern at 24 months. Propensity score analyses were consistent with regression analyses. This study suggests that dietary patterns from 6 to 24 months may have a small but persistent effect on IQ at 8 years.

Age- and puberty-dependent association between IQ score in early childhood and depressive symptoms in adolescence.

BackgroundLower cognitive functioning in early childhood has been proposed as a risk factor for depression in later life but its association with depressive symptoms during adolescence has rarely been investigated. Our study examines the relationship between total intelligence quotient (IQ) score at age 8 years, and depressive symptoms at 11, 13, 14 and 17 years.MethodStudy participants were 5250 children and adolescents from the Avon Longitudinal Study of Parents and their Children (ALSPAC), UK, for whom longitudinal data on depressive symptoms were available. IQ was assessed with the Wechsler Intelligence Scale for Children III, and self-reported depressive symptoms were measured with the Short Mood and Feelings Questionnaire (SMFQ).ResultsMulti-level analysis on continuous SMFQ scores showed that IQ at age 8 years was inversely associated with depressive symptoms at age 11 years, but the association changed direction by age 13 and 14 years (age–IQ interaction, p<0.0001; age squared–IQ interaction, p<0.0001) when a higher IQ score was associated with a higher risk of depressive symptoms. This change in IQ effect was also found in relation to pubertal stage (pubertal stage–IQ interaction, 0.00049<p⩽0.038). At age 17 years, however, sex-specific differences emerged (sex–age squared–IQ interaction, p=0.0075). Whilst the risk effect of higher childhood IQ scores for depressive symptoms declined in females, and some analyses even supported an inverse association by age 17 years, it persisted in males.ConclusionsOur results suggest that the association between cognitive ability in childhood and depressive symptoms in adolescence varies according to age and/or pubertal stage.

Pre-morbid intelligence, the metabolic syndrome and mortality: the Vietnam Experience Study

We examined the relationship between pre-morbid intelligence quotient (IQ) and the metabolic syndrome, and assessed the role of the metabolic syndrome as a mediating factor in the association of IQ with total and cardiovascular disease (CVD) mortality. In this cohort study, 4,157 men with IQ test results from late adolescence or early adulthood [mean age (range) 20.4 (16-30) years] attended a clinical examination in middle-age [38.3 (31-46) years] at which the components of the metabolic syndrome were measured. They were then followed for 15 years to assess mortality. In age-adjusted analyses, IQ was significantly inversely related to four of the five individual components comprising the metabolic syndrome: hypertension, high BMI, high triglycerides and high blood glucose, but not low HDL-cholesterol. After controlling for a range of covariates that included socioeconomic position, higher IQ scores were associated with a reduced prevalence of the metabolic syndrome itself (odds ratio(1 SD increase in IQ) 0.87, 95% CI 0.78-0.98). Structural equation modelling revealed that education was not a mediator of the relationship between IQ and the metabolic syndrome. The metabolic syndrome partially mediated the relationship between IQ and CVD but not that between IQ and total mortality. In this cohort, higher scores on a pre-morbid IQ test were associated with a lower prevalence of the metabolic syndrome and most of its components. The metabolic syndrome was a mediating variable in the IQ-CVD relationship.

Sleep spindles and learning potential.

The number of sleep spindles remains relatively stable within individuals from night to night. However, there is little explanation for the large interindividual differences in spindles. The authors investigated the relationship between spindles and intelligence quotient (IQ) in 3 separate studies. The number of spindles and sigma power were positively correlated with performance IQ (PIQ), but not verbal IQ (VIQ). The perceptual/analytical skills measured by the PIQ Picture Completion subscale accounted for most of the interindividual differences in spindles. Furthermore, there was a relationship between the rapid eye movements (REMs) of REM sleep and VIQ in individuals with higher IQ scores. A similar pattern was observed between spindles and PIQ. It was hypothesized that high-IQ individuals have more spindles that can support more complex cortical networks underlying perceptual/analytical abilities.