Adjustment For IQ Research Articles

Relationships between intelligence, executive function and academic achievement in children born very preterm

BackgroundChildren born very preterm are at higher risk of adverse neurocognitive and educational outcomes. However, how low intelligence (IQ) and low executive function may each contribute to poorer academic outcomes at school age requires clarification. AimTo examine the associations between intelligence, executive function and academic achievement in children born very preterm. Design/methodsThis cohort study assessed children born <30 weeks' gestation or <1500 g at age 7 years using the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) for IQ, and the Test of Everyday Attention for Children (TEA-Ch) and Behavior Rating Inventory of Executive Function (BRIEF) for executive function. Academic achievement was rated by teachers against curriculum standards. ResultsOf the 76 children (35 girls, 41 boys, mean age = 7.2 year), 22 (28%) were rated below expected level for reading, 32 (42%) for writing and 38 (50%) for mathematics. After adjustment for sex and socioeconomic status, low IQ (OR's 9.0–12.3) and most low executive function measures (OR's 4.1–9.3) were associated with below-expected achievement. After further adjustment for IQ, low cognitive flexibility (OR = 9.3, 95% CI = 1.2–71.5) and teacher ratings of executive function (OR = 5.3, 95% CI = 1.4–20.2) were associated with below-expected achievement. Mediation analysis showed IQ had indirect effects on writing (b = 1.5, 95% CI = 0.6–3.1) via attentional control; and on reading (b = 1.0, 95% CI = 0.2–3.2) and writing (b = 0.8, 95% CI = 0.1–2.5) via cognitive flexibility. ConclusionsBoth low IQ and low executive function are associated with below-expected teacher-rated academic achievement in children born very preterm. IQ may influence academic achievement in part through executive function.

Inattention and Hyperactivity in Children with Symptomatic and Asymptomatic Congenital Cytomegalovirus.

To explore the relationship between congenital cytomegalovirus (CMV) and inattention and hyperactivity among school-aged children. The Behavior Assessment System for Children, Second Edition, parent- and self-report, was completed among children with symptomatic congenital CMV (ScCMV) (n = 36), asymptomatic congenital CMV (AcCMV) (n = 76), and controls (n = 29) enrolled in a longitudinal cohort. The proportions of children with ScCMV, AcCMV, and controls with Attention Problems or Hyperactivity T-scores ever ≥ 65 were compared. Mean T-scores in these domains were also compared and adjusted for IQ. Children with AcCMV did not differ from controls in the proportion of children with elevated Attention Problems or Hyperactivity T-scores or in mean Attention Problems or Hyperactivity T-scores. Children with ScCMV had a higher proportion of elevated Attention Problems T-scores compared with the AcCMV group but not controls. There were no differences in the proportions of children with elevated Hyperactivity T-scores between ScCMV and AcCMV or control groups. Children with ScCMV had higher mean Attention Problems T-scores versus those with AcCMV and controls and higher mean Hyperactivity T-scores versus those with AcCMV but not controls. After adjustment for IQ, differences in mean Attention Problems or Hyperactivity T-scores were no longer significant. Children with AcCMV are not at increased risk of inattention or hyperactivity compared with controls. However, our study suggests an increased prevalence of inattention and hyperactivity among children with ScCMV. Differences in IQ were confirmed to have a confounding effect. Evaluation for attention-deficit/hyperactivity disorder may be warranted in this population.

Impairment in delay discounting in schizophrenia and schizoaffective disorder but not primary mood disorders

A measure of planning and impulse control, the delay-discounting (DD) task estimates the extent to which an individual decreases the perceived value of a reward as the reward is delayed. We examined cross-disorder performance between healthy controls (n = 88), individuals with bipolar disorder (n = 23), major depressive disorder (n = 43), and primary psychotic disorders (schizophrenia and schizoaffective disorder; n = 51) on the DD task (using a $10 delayed larger reward), as well as the interaction of DD scores with other symptom domains (cognition, psychosis, and affect). We found that individuals with schizophrenia and schizoaffective disorder display significantly greater rates of discounting compared to healthy controls, while individuals with a primary mood disorder do not differ from healthy controls after adjustment for IQ. Further, impairment in working memory is associated with higher discounting rates among individuals with schizophrenia and schizoaffective disorder, but cognitive dysfunction alone does not account for the extent of impairment in DD. Taken together, these results suggest an impaired ability to plan for the future and make adaptive decisions that are specific to individuals with psychotic disorders, and likely related to adverse functional outcomes. More generally, this work demonstrates the presence of variation in impulsivity across major psychiatric illnesses, supporting the use of a trans-diagnostic perspective.

Artistic creativity and risk for schizophrenia, bipolar disorder and unipolar depression: a Swedish population-based case-control study and sib-pair analysis.

Many studies have addressed the question of whether mental disorder is associated with creativity, but high-quality epidemiological evidence has been lacking.AimsTo test for an association between studying a creative subject at high school or university and later mental disorder. In a case-control study using linked population-based registries in Sweden (N = 4 454 763), we tested for associations between tertiary education in an artistic field and hospital admission with schizophrenia (N = 20 333), bipolar disorder (N = 28 293) or unipolar depression (N = 148 365). Compared with the general population, individuals with an artistic education had increased odds of developing schizophrenia (odds ratio = 1.90, 95% CI = [1.69; 2.12]) bipolar disorder (odds ratio = 1.62 [1.50; 1.75]) and unipolar depression (odds ratio = 1.39 [1.34; 1.44]. The results remained after adjustment for IQ and other potential confounders. Students of artistic subjects at university are at increased risk of developing schizophrenia, bipolar disorder and unipolar depression in adulthood.Declaration of interestNone.

O8.8. NEUROCOGNITION IN ULTRA-HIGHRISK INDIVIDUALS AND RELATIONSHIP TO TRANSITION TO PSYCHOSIS, DEPRESSIVE DISORDER, AND FUNCTIONING: FINDINGS FROM THE NEURAPRO TRIAL

BackgroundNeurocognitive impairments are a core feature of psychosis and major depressive disorder (MDD) and are associated with poorer functioning outcomes in these illnesses. Individuals at ultra-high risk (UHR) for psychosis have been shown to experience mild but significant cognitive impairments relative to healthy controls. Evidence suggests neurocognitive deficits are useful predictors of transition to psychotic disorder, although there is inconsistency regarding the specific domains implicated. Furthermore, depression is common in the UHR population, but the relationship between neurocognitive impairment and depression in UHR has not been investigated. The aim of this study was to examine neurocognitive functioning in UHR participants at baseline and whether neurocognitive performance is associated with i) transition to psychosis; ii) depressive disorder; and iii) functioning at medium-term follow-up (median 24 months).MethodsSecondary analysis of data collected as part of a multi-centre RCT of omega-3 fatty acids and cognitive behavioural case management (NEURAPRO) for individuals at UHR for psychosis was conducted. Baseline, 6, 12 and 24-month (median) assessments relevant to the current study included the Comprehensive Assessment of the At-Risk Mental State (CAARMS), Structured Clinical Interview for DSM-IV (SCID), Brief Assessment of Cognition for Schizophrenia (BACS), Montgomery–Åsberg Depression Rating Scale (MADRS) and Social and Occupational Functioning Assessment Scale (SOFAS). The analysis was conducted on the 287 UHR participants (129 males, 158 females) who completed these measures. Hierarchical Cox proportional hazards regression was used to examine neurocognitive predictors of transition to psychosis, while hierarchical logistic and linear regressions were used to identify neurocognitive predictors of MDD and functioning, respectively.ResultsMean z-scores at baseline indicated that the UHR participants performed on average a quarter to half a standard deviation below healthy people in most domains (range mean z=-0.24 to -0.47), except for executive functioning (mean z=0.16, SD=1.21). One hundred and nineteen (41.5%) participants met criteria for MDD at baseline. Thirty-eight (13.2%) participants transitioned to psychosis over 24 months. Results showed that poorer Executive (p=.01) and Motor (p=.03) functions were predictive of transition to psychosis over 24 months, after controlling for other clinical and treatment variables. Forty-eight (16.7%) participants met criteria for MDD at 24 months. Faster Processing Speed significantly predicted MDD at 24 months (p=.01), but failed to retain significance after controlling for other factors, with baseline and past MDD history emerging as the strongest predictors of MDD at medium-term follow-up (both p<.001). After adjustment for IQ and baseline functioning, functional outcomes at 6, 12 and 24 months were predicted by baseline Processing Speed.DiscussionThese findings suggest that neurocognitive abilities are important predictors of transition to psychosis and functional outcomes within the UHR population, but hold minimal value in predicting MDD after controlling for history of MDD. Further research is needed that examines trajectory of neurocognition over time in UHR and in relation to psychopathology and functioning outcomes.

Digit ratio and autism spectrum disorders in the Avon Longitudinal Study of Parents and Children: a birth cohort study

ObjectivesTo investigate whether second-to-fourth digit ratio (2D:4D), a measure commonly used as a proxy for fetal testosterone exposure, is associated with autism spectrum disorders (ASDs), as predicted by the extreme...

Verbal learning and memory impairment in children with fetal alcohol spectrum disorders.

Previous studies using the California Verbal Learning Test-Children's Version (CVLT-C) to examine effects of heavy prenatal alcohol exposure on verbal learning and memory have reported impaired information acquisition (i.e., encoding), rather than retrieval, as the primary mechanism underlying learning and memory impairment. We administered the CVLT-C to 2 independent cohorts to determine whether (i) effects on encoding are also seen at moderate exposure levels, using both categorical (diagnostic/exposure group) and continuous exposure measures; (ii) these deficits are specific or secondary to alcohol-related impairment in IQ; (iii) effects on retrieval can be detected over and above effects on initial encoding; and (iv) effects on learning are attributable to less efficient learning strategy use. We administered the CVLT-C and Wechsler Intelligence Scale for Children to 151 Cape Town heavy and nonexposed children (M=10.3years), and 291 Detroit adolescents recruited to over-represent moderate-to-heavy prenatal alcohol exposure (M=14.4years). Effects on encoding in the heavily exposed Cape Town cohort and on retrieval in both cohorts were significant after adjustment for IQ. Although effects on retrieval were no longer significant in Cape Town after control for initial encoding, effects on recognition memory continued to be evident in Detroit. Children with full or partial fetal alcohol syndrome were less able to use the semantic cluster encoding strategy implicit in the CVLT-C. Effects on verbal learning were seen primarily in the more heavily exposed Cape Town cohort; effects on recall and recognition memory were also seen at moderate exposure levels in Detroit. These effects were not attributable to alcohol-related impairment in overall intellectual competence. The finding that effects on retention continued to be evident after statistical adjustment for initial encoding in Detroit suggests that a fetal alcohol-related deficit in retrieval is not secondary to a failure to encode the initial information. These data confirm that this impairment in initial learning is mediated, in part, by failure to use the semantic cluster learning strategy.

Neurobehavioural correlates in older children and adolescents with obesity and obstructive sleep apnoea

The relationship between obstructive sleep apnoea (OSA) and poorer neurobehavioural outcomes in school-age children is well established, but the relationship in obese children and adolescents, in whom OSA is more common, is not so well established. We aimed to investigate this relationship in 10-18-year-olds. Thirty-one participants with a mean body mass index (BMI) of 32.3 ± 4.9 enrolled. BMI-for-age cut-offs were used to define obesity. Participants underwent polysomnography and were classified into OSA (apnoea-hypopnoea index (AHI) > 2 per hour) and non-OSA (AHI ≤ 2) groups. Intelligence, memory and learning, academic achievement, behaviour and executive functioning were assessed using the Wechsler Abbreviated Scale of Intelligence, Wide Range Assessment of Memory and Learning 2, Wechsler Individual Achievement Test II (WIAT-II), Behavioural Assessment System for Children 2 and Behaviour Rating Inventory of Executive Function, respectively. Forty-eight per cent (15/31) were classified as having OSA, and 52% (16/31) as non-OSA. The obese cohort performed below the average of normative data on several neurobehavioural measures. WIAT-II maths scores were significantly lower (P = 0.034) in the OSA group than in the non-OSA group (means 84.5 vs. 94.6, respectively), losing significance after adjustment for IQ, age and gender. Self-reported school problems were significantly worse in the OSA group before and after multivariate adjustment (P = 0.010, Cohen's d = 1.02). No other significant differences were found. Results suggest that OSA may increase risk for some poorer educational and behavioural outcomes. The findings are reasonably consistent with and add to the evidence base of the few studies that have explored this relationship.

Adaptive behavior and later school achievement in children with early‐onset epilepsy

To determine whether early measures of adaptive behavior are predictive of later school difficulties and achievement in otherwise neurotypical (unimpaired) children with onset of epilepsy during the preschool years. In a prospective cohort study, parents completed the Vineland Adaptive Behavior Scales (VABS) for children who were aged 5 years or less at epilepsy diagnosis. Eight to 9 years later, the children were assessed using the Wechsler Intelligence Scales for Children (WISC), the Wide Range Achievement Test (WRAT), and the Child Behavior Checklist (CBCL). Associations of VABS scores with later WRAT and CBCL scores were tested. A total of 108 neurotypical children (64 males, 44 females; mean age at testing 11 y 11 mo, SD 2 y) were studied. After adjustment for IQ and other factors, there was an increase of 0.15 points (95% confidence interval [CI] 0.03-0.27 points; p=0.03) and 0.14 points (95% CI 0.0-0.28 points; p=0.05) in WRAT reading and spelling scores for each 1-point increment in the VABS communication score. Corresponding numbers for the VABS socialization score were 0.20 (95% CI 0.08-0.32; p=0.005) and 0.17 (95% CI 0.05-0.29; p=0.005). In neurotypical preschool children with epilepsy, early social and communication scores predict later school performance. These findings raise questions about opportunities for early identification and intervention for children at greatest risk.

Infant Malnutrition Is Associated with Persisting Attention Deficits in Middle Adulthood1–3

Infantile malnutrition is known to be associated with cognitive and behavioral impairment during childhood and adolescence. Data pertaining to longer-term effects on behavioral outcomes in adulthood are limited. In this study, we report associations between infantile malnutrition and attention problems in adults at midlife. Attention problems were assessed by the Conners Adult ADHD Rating Scales (CAARS) and the Conners Continuous Performance Test (CPT) in 145 Barbadian adults (aged 3743 y) who had been followed longitudinally since childhood. Previously malnourished participants (n = 80) had experienced moderate to severe protein-energy malnutrition in the first year of life and were successfully rehabilitated thereafter. They were compared with healthy adults (n = 65) who were former classmates of the index cases and who had been matched for age, sex, and handedness in childhood. Multiple regression analyses showed persisting effects of childhood malnutrition on both the CAARS and the CPT, independent of effects of household standard of living assessed in childhood. The malnutrition effect on the CAARS ratings was independent of IQ, whereas this effect was attenuated for the CPT after adjustment for IQ. Teacher-reported attention problems in childhood predicted attention problems in adulthood, indicating continuity over the life span. Infantile malnutrition may have long-term effects on attentional processes nearly 40 y after the episode, even with excellent long-term nutritional rehabilitation and independent of socioeconomic conditions in childhood and adolescence. This finding has major public health implications for populations exposed to early childhood malnutrition.

Genome scan for spelling deficits: effects of verbal IQ on models of transmission and trait gene localization.

Dyslexia is a complex learning disability with evidence for a genetic basis. Strategies that may be useful for dissecting its genetic basis include the study of component phenotypes, which may simplify the underlying genetic complexity, and use of an analytic approach that accounts for the multilocus nature of the trait to guide the investigation and increase power to detect individual loci. Here we present results of a genetic analysis of spelling disability as a component phenotype. Spelling disability is informative in analysis of extended pedigrees because it persists into adulthood. We show that a small number of hypothesized loci are sufficient to explain the inheritance of the trait in our sample, and that each of these loci maps to one of four genomic regions. Individual trait models and locations are a function of whether a verbal IQ adjustment is included, suggesting mediation through both IQ-related and unrelated pathways.

Does IQ explain socio-economic differentials in total and cardiovascular disease mortality? Comparison with the explanatory power of traditional cardiovascular disease risk factors in the Vietnam Experience Study

The aim of this study was to examine the explanatory power of intelligence (IQ) compared with traditional cardiovascular disease (CVD) risk factors in the relationship of socio-economic disadvantage with total and CVD mortality, that is the extent to which IQ may account for the variance in this well-documented association. Cohort study of 4289 US male former military personnel with data on four widely used markers of socio-economic position (early adulthood and current income, occupational prestige, and education), IQ test scores (early adulthood and middle-age), a range of nine established CVD risk factors (systolic and diastolic blood pressure, total blood cholesterol, HDL cholesterol, body mass index, smoking, blood glucose, resting heart rate, and forced expiratory volume in 1 s), and later mortality. We used the relative index of inequality (RII) to quantify the relation between each index of socio-economic position and mortality. Fifteen years of mortality surveillance gave rise to 237 deaths (62 from CVD and 175 from 'other' causes). In age-adjusted analyses, as expected, each of the four indices of socio-economic position was inversely associated with total, CVD, and 'other' causes of mortality, such that elevated rates were evident in the most socio-economically disadvantaged men. When IQ in middle-age was introduced to the age-adjusted model, there was marked attenuation in the RII across the socio-economic predictors for total mortality (average 50% attenuation in RII), CVD (55%), and 'other' causes of death (49%). When the nine traditional risk factors were added to the age-adjusted model, the comparable reduction in RII was less marked than that seen after IQ adjustment: all-causes (40%), CVD (40%), and 'other' mortality (43%). Adding IQ to the latter model resulted in marked, additional explanatory power for all outcomes in comparison to the age-adjusted analyses: all-causes (63%), CVD (63%), and 'other' mortality (65%). When we utilized IQ in early adulthood rather than middle-age as an explanatory variable, the attenuating effect on the socio-economic gradient was less pronounced although the same pattern was still present. In the present analyses of socio-economic gradients in total and CVD mortality, IQ appeared to offer greater explanatory power than that apparent for traditional CVD risk factors.

IQ, Socioeconomic Status, and Early Death: The US National Longitudinal Survey of Youth

To assess whether the association between cognitive ability (IQ) and early mortality is mediated by socioeconomic status (SES) or whether the association between SES and mortality reflects a spurious association caused by IQ. The participants were from the US National Longitudinal Survey of Youth (n = 11,321). IQ was assessed at age 16 to 23 years and the participants were followed up to 40 to 47 years of age. Controlling for sex, birth year, race/ethnicity, baseline health, and parental education, higher IQ was associated with lower probability of death (odds ratio (OR) per 1-standard deviation increase in IQ = 0.78, 95% confidence interval (CI) = 0.66, 0.91). This association disappeared (OR = 0.99, 95% CI = 0.81, 1.20) when adjusted for education and household income. Adjustment for IQ had no effect on the association between SES and mortality. These findings were similar in Hispanic, Black, and White/other participants and in women and men. Parental education moderated the IQ-mortality association so that this association was not observed in participants with low parental education. Low IQ predicts early mortality in the US population and this association is largely explained by SES. The results do not support the alternative hypothesis that the socioeconomic gradient in early mortality would reflect IQ differences.

Does IQ explain socioeconomic inequalities in health? Evidence from a population based cohort study in the west of Scotland

Objective To test the hypothesis that IQ is a fundamental cause of socioeconomic inequalities in health.Design Cross sectional and prospective cohort study, in which indicators of IQ were assessed by...

Alterations in theory of mind in patients with schizophrenia and non-psychotic relatives.

It has been proposed that alterations in theory of mind underlie specific symptoms of psychosis. The present study examined whether alterations in theory of mind reflect a trait that can be detected in non-psychotic relatives of patients with schizophrenia. Participants were 43 patients with schizophrenia or schizoaffective disorder, 41 first-degree non-psychotic relatives and 43 controls from the general population. Theory of mind was assessed using a hinting task and a false-belief task. There was a significant association between schizophrenia risk and failure on the hinting task (OR linear trend = 2.01, 95% CI: 1.22-3.31), with relatives having intermediate values between patients and controls. Adjustment for IQ and neuropsychological factors reduced the association by small amounts. The association between schizophrenia risk and failure on the false-belief tasks was not significant. Changes in theory of mind are associated with schizophrenia liability. General cognitive ability and neuropsychological measures seem to mediate only part of this association.

Organic solvent exposure, genes, and risk of neuropsychological impairment.

Subtle cognitive and neurological impairments have been found in some workers exposed to organic solvents. Whether these effects occur at or below current legal limits for occupational exposure is controversial. To determine whether occupational solvent exposure is associated with neuropsychological impairment and whether such risk is modified by polymorphisms in the genes for enzymes involved in detoxification. Retrospective case-control analysis. We studied 78 former dockyard painters and 42 community controls. Individual respiratory and dermal exposures to solvents were estimated. Neuropsychological tests were administered, including paper and pencil tests, tests from the Neurobehavioural Evaluation System (NES2), together with a structured neurological examination and genotyping of polymorphic enzymes involved in detoxification: GSTM1, GSTT1, GSTP1, NAT1, NAT2, SOD1 and CYP1A1. While initial case-control analyses failed to identify any significant differences between symptomatic and asymptomatic painters, in regression analyses increasing solvent exposure was associated with increasing risk of cognitive impairment, after adjustment for IQ (or age, where appropriate), smoking and alcohol. There was also an association between exposure and reduction in grip strength. There was limited evidence of risk modification by some enzyme polymorphisms. This association between increasing intensity of solvent exposure and neuropsychological impairment may be important at current exposure levels in the UK.

Bilingual Children Referred for Psychiatric Services: Associations of Language Disorders, Language Skills, and Psychopathology

To investigate (1) the prevalence of language deficits and disorders and (2) the relationship of bilingual language skills and psychopathology, in Spanish-English bilingual children referred for child and adolescent psychiatry services. Bilingual language skills, emotional/behavioral problems, sociodemographics, immigration variables, and nonverbal IQ were studied in 50 consecutively referred children. Estimated prevalence was high for language deficits (48%) and disorders (41%), with most cases (>79%) being of the mixed receptive-expressive type. In children with clinically significant emotional/behavioral problems, bilingual language skills were strongly and inversely correlated with problem scores, particularly global problems (r = -0.67, p < .001); social, thought, and attention problems (r > or = -0.54; p < .004); delinquency (r = -0.66, p < .001); and aggression (r = -0.52, p < .01). These correlations remained significant after IQ adjustment. Prior findings from monolingual children were confirmed in this bilingual sample, namely (1) the high prevalence of mixed receptive-expressive and other language disorders and delays and (2) the close tie between poor language skills and emotional/behavioral problems. The data strongly suggest the clinical importance and feasibility of language assessment and the significance of receptive problems in bilingual children referred for psychiatric services. A safe approach is to fully assess language skills, rather than misattributing these children's language delays to normal bilingual acquisition processes.

Low birth weight as a vulnerability marker for early drug use.

Using prospective data from a community-based sample, the authors tested (a) whether low birth weight (LBW) was a vulnerability marker for children's early drug use and (b) whether the antecedents and sequelae of LBW may act as mediators or confounders in the pathway to early drug use. A total of 823 children and their mothers--473 LBW (<2,500 g) and 350 normal birth weight (NBW)--were assessed when the children were 6 years old and again when they were 11 years old. The incidence of drug use was higher in LBW versus NBW boys (relative odds = 2.0, 95% confidence interval = 1.2-2.6), but there was no difference in incidence for girls. The increased risk for LBW boys remained after adjustment for IQ, externalizing problems, attention-deficit/hyperactivity disorder, and maternal smoking. These findings suggest that LBW is a useful vulnerability marker for early drug use among boys, independent of the antecedents and sequelae of LBW.