Rising IQ scores in British children: recent evidence

It Runs in the Family: Testing for Longitudinal Family Flynn Effects

The Flynn effect refers to increases over time in measured (particularly fluid) intelligence of approximately 3 IQ points per decade. We define the Flynn effect at the family level, using longitudinal data and two new family-level cohort definitions. Multilevel growth curve analyses of the National Longitudinal Survey of Youth 1979 data showed that children in families with later-born mothers had higher average PIAT math scores, and lower average reading comprehension scores and growth, in young and middle childhood. Children in families where the first child was born later had higher average PIAT math, reading recognition, and reading comprehension scores, as well as larger developmental growth. The latter family-level Flynn effects were of higher magnitudes than the usual individual-level Flynn effect found in previous studies. Our results, showing family level-intercept and slope Flynn effects for both maternal birthyear and first child birthyear, have implications for research aiming to explain the Flynn effect.

One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909-2013)

The Flynn effect (rising intelligence test performance in the general population over time and generations) varies enigmatically across countries and intelligence domains; its substantive meaning and causes remain elusive. This first formal meta-analysis on the topic revealed worldwide IQ gains across more than one century (1909-2013), based on 271 independent samples, totaling almost 4 million participants, from 31 countries. Key findings include that IQ gains vary according to domain (estimated 0.41, 0.30, 0.28, and 0.21 IQ points annually for fluid, spatial, full-scale, and crystallized IQ test performance, respectively), are stronger for adults than children, and have decreased in more recent decades. Altogether, these findings narrow down proposed theories and candidate factors presumably accounting for the Flynn effect. Factors associated with life history speed seem mainly responsible for the Flynn effect's general trajectory, whereas favorable social multiplier effects and effects related to economic prosperity appear to be responsible for observed differences of the Flynn effect across intelligence domains.

Long-term outcomes of pneumococcal meningitis in childhood and adolescence

A vaccine to prevent pneumococcal meningitis (PM) has recently been introduced. However, contemporary data to inform cost-effectiveness analysis and justify its routine use are sparse. We examined the cognitive, educational, psychological and social outcomes of PM in childhood. We completed a population-based case-control study in two regions of the UK. Children and young people currently between 3 and 20 years of age that had been diagnosed with PM ≤14 years of age were identified from active regional surveillance. Controls were siblings or neighbours of similar age. Standardised questionnaires and neuropsychological testing was administered to assess IQ, educational attainments, memory, psychological distress, quality of life and hearing impairment. Data were available on 97 patients and 93 controls. Eighty-four patients had a sibling/neighbour-matched control. Both matched and unmatched analyses were completed, and results of the 84 matched comparisons were highly similar to the unmatched. For the total sample, controls were similar in age, ethnicity and socioeconomic status. Median age at meningitis was 11 months. Median time between meningitis and assessment was 6.0 years. In the matched analysis, partial or profound hearing impairment was reported in 14% of patients and 1% of controls. Patients had significantly lower mean full-scale IQ (p = 0.05), verbal IQ (p = 0.0008), numeracy (p = 0.02), total quality of life (p = 0.04), school functioning (p = 0.005), psychosocial functioning (p = 0.001) and psychological difficulties (p = 0.01). Parents of patients reported greater functional disability (p = 0.008), impairment in all aspects of quality of life (p = 0.001) and psychological difficulties (p < 0.0006). Findings for IQ were not materially different when analyses were repeated only in those without hearing impairment. In multivariate regression analysis that included both case-control status and hearing status, both being a patient (p = 0.001) and having profound hearing impairment (p = 0.001) were independently associated with lower full-scale IQ. Conclusions Pneumococcal meningitis is associated with major sequelae. Our findings strongly support the introduction of pneumococcal conjugate vaccine as part of routine childhood vaccination programmes internationally.

Neurodevelopmental disability through 11 years of age in children born before 26 weeks of gestation

BACKGROUND

To assess functional disability in children born before 26 weeks of gestation at 11 years of age and the stability of findings in individuals between 6 and 11 years of age.

METHODS

Of 307 surviving children born in 1995, 219 (71%) were assessed at 11 years of age alongside 153 classmates. Children were evaluated by using standardized tests of cognitive ability and clinical condition at both ages.

RESULTS

Using classmate data to determine reference ranges, serious cognitive impairment (score of less than -2 SD) was present in 40% of extremely preterm children and 1.3% of classmates (odds ratio [OR]: 50 [95% confidence interval (CI): 12-206]) at 11 years of age. Overall, 38 (17%) extremely preterm children had cerebral palsy; moderate or severe impairment of neuromotor function, vision, and hearing was present in 10%, 9%, and 2% of these children, respectively. Combining impairment across domains, 98 (45%) extremely preterm children had serious functional disability compared with 1% of the classmates (OR: 61 [95% CI: 15-253]); this was more common in boys than girls (OR: 1.8 [95% CI: 1.0-3.1]) and in those born at 23 or 24 weeks' gestation compared with those born at 25 weeks' gestation (OR: 1.8 [95% CI: 1.0-3.1]). The prevalence of serious functional disability was 46% at 6 years of age and 45% at 11 years of age. Using multiple imputation to correct for selective dropout, it is estimated that 50% (95% CI: 44%-57%) of extremely preterm children are free of serious disability at 11 years of age.

CONCLUSIONS

Extremely preterm children remain at high risk for neurodevelopmental disability at 11 years of age compared with term peers. The prevalence of disability remained stable between 6 and 11 years of age, and large individual shifts in classification of disability were unusual.

Outcome Monitoring in Preterm Populations

Routine neurodevelopmental follow-up is crucial in high-risk populations, such as those born very preterm. Even in the absence of severe neurosensory impairment, very preterm children are at risk for a range of long-term cognitive, motor, and learning deficits. Infant developmental assessments are typically carried out at 2 years of age for both clinical and research purposes, and they are crucial for outcome monitoring. We review psychometric tests of infant developmental functioning most widely used as outcome measures for very preterm infants and other high-risk populations. We also consider parent-based assessments and methodological issues pertaining to the use of these tools in large-scale research studies and in outcome monitoring in this population.

Language development at ten months. Predictive of language outcome and school achievement ten years later?

AIMS

Language development was followed from infancy to primary school age in order to examine the predictive significance for later language and scholastic outcome.

METHODS

Participants were from a prospective longitudinal study of a birth cohort of initially 362 children. A subsample of 90 children (54 boys, 36 girls) was administered with the Receptive-Expressive Emergent Language Scale (REEL) in order to obtain age-appropriate measures of expressive and receptive language at the age of 10 months. At 11 years, children completed a comprehensive test battery assessing various intellectual skills and language performance. Scholastic measures included a school performance score and a recommendation for type of secondary school.

RESULTS

Both expressive and receptive language performance at 10 months were significantly associated with cognitive and educational outcome 10 years later. Infant language performance not only predicted later verbal and nonverbal skills but also school achievement at the end of primary school. Prediction was higher in girls than in boys and slightly better for verbal and academic than for nonverbal performance.

CONCLUSIONS

The results demonstrate the importance of early language abilities in predicting cognitive and academic outcome at school age.

Maternal hypothyroxinaemia during early pregnancy and subsequent child development: a 3-year follow-up study

OBJECTIVE

To evaluate the impact of maternal hypothyroxinaemia during early gestation (fT4 below the lowest tenth percentile and TSH within the reference range: 0.15-2.0 mIU/l) on infant development, together with any subsequent changes in fT4 during gestation.

DESIGN

A prospective 3-year follow-up study of pregnant women and their children up to the age of 2 years.

MEASUREMENTS

Child development was assessed by means of the Bayley Scales of Infant Development in children of women with hypothyroxinaemia (fT4 below the tenth percentile at 12 weeks' gestation) at 12 weeks' gestation (cases), and in children of women with fT4 between the 50th and 90th percentiles at 12 weeks' gestation, matched for parity and gravidity (controls). Maternal thyroid function (fT4 and TSH) was assessed at 12, 24 and 32 weeks' gestation. The mental and motor function of 63 cases and 62 controls was compared at the age of 1 year, and of 57 cases and 58 controls at the age of 2 years.

RESULTS

Children of women with hypothyroxinaemia at 12 weeks' gestation had delayed mental and motor function compared to controls: 10 index points on the mental scale (95% CI: 4.5-15 points, P = 0.003) and eight on the motor scale at the age of 1 year (95% CI: 2.3-12.8 points, P = 0.02), as well as eight index points on the mental (95% CI: 4-12 points, P = 0.02), and 10 on the motor scale (95%CI: 6-16 points, P = 0.005) at the age of 2 years. Children of hypothyroxinaemic women in whom the fT4 concentration was increased at 24 and 32 weeks' gestation had similar scores to controls, while in the controls, the developmental scores were not influenced by further declines in maternal fT4 at 24 and 32 weeks' gestation.

CONCLUSIONS

Maternal hypothyroxinaemia during early gestation is an independent determinant of a delay in infant neurodevelopment. However, when fT4 concentrations increase during pregnancy in women who are hypothyroxinaemic during early gestation, infant development appears not to be adversely affected.

Beeinträchtigte kognitive und motorische Leistungen bei 8jährigen Kindern mit sehr niedrigem Geburtsgewicht

Zusammenfassung. Theoretischer Hintergrund: Es ist belegt, daß VLBW-Kinder (< 1500g) vermehrt motorische und/oder geistige Behinderungen aufweisen. Dagegen werden subtilere Beeinträchtigungen ohne offensichtliche Behinderung kontrovers diskutiert. Fragestellung: Das kognitive Leistungsprofil und grobmotorische Fertigkeiten von 33 neurologisch unauffälligen 8jährigen VLBW-Kindern werden mit 224 NBW-Kindern (≥ 2500g) verglichen. Methode: Die Daten resultieren aus einer prospektiven Längsschnittstudie mit 362 Kindern mit unterschiedlicher organischer und psychosozialer Risikobelastung. Ergebnisse: Nonverbale Funktionen der VLBW-Gruppe fielen signifikant schlechter als in der NBW-Gruppe aus, während verbale Fähigkeiten unauffällig waren. Unabhängig vom Geburtsgewicht beeinträchtigte eine hohe psychosoziale Belastung ausschließlich sprachliche Leistungen. Intraindividuelle Profilanalysen der VLBW-Gruppe ergaben keine spezifischen Defizite. Schlußfolgerung: Die Ergebnisse unterstützen die Annahme von suboptimalen rechtshemisphärischen Funktionen bei VLBW-Kindern sowie eine additive Verknüpfung von psycho-sozialer Belastung und niedrigem Geburtsgewicht.

Returning to school after heart or heart-lung transplantation: how well do children adjust?

BACKGROUND

Up to 40% of children and adolescents with chronic illness experience school-related problems, including learning difficulties and problems in social adjustment and peer relationships. Despite the life-threatening nature of heart and heart-lung transplantation and the severity of illness, which results in the necessity for surgery, there is little information on the school performance of children after transplantation.

METHODS

Eighty-one children and adolescents were assessed with regard to their academic attainments and behavior at school at regular intervals after heart (n=47) or heart-lung (n=34) transplantation and comparisons made with a group of healthy children.

RESULTS

Cognitive ability and performance on academic attainments were within the normal range and did not change significantly as a function of time since transplant. However, performance was at a significantly lower level than that of the healthy children. Although the prevalence of behavior problems was only 8% at 6 months posttransplant, at 3 years, it had increased to 29% and, at 5 years, it was still 27%. Children with an initial diagnosis of congenital heart disease had more academic and behavioral difficulties than those with either cardiomyopathy or cystic fibrosis.

CONCLUSIONS

A significant number of children who had undergone successful transplantation experienced difficulties at school. Contrary to expectations, educational problems were more prevalent in the medium term, rather than short term, after transplant. Initial diagnosis was a salient factor in posttransplant psychological functioning at school. Early intervention and close liaison with schools is indicated to reduce psychological morbidity and enhance adaptation within the school environment.

Congenital heart disease and cardiac surgery in childhood: effects on cognitive function and academic ability

OBJECTIVE

To evaluate changes in cognitive and academic functioning following cardiac surgery in children with congenital heart disease.

DESIGN

A prospective cross sectional study in which patients were assessed immediately before treatment and 12 months later.

PATIENTS

Three groups of children aged 3.5-17 years: a group with congenital heart disease awaiting surgery, another awaiting bone marrow transplantation, and a healthy comparison group.

MAIN OUTCOME MEASURES

Intelligence quotient and measures of academic attainment, evaluated with the British Ability Scales.

RESULTS

Preoperatively, children with cyanotic lesions showed deficits in comparison with those with acyanotic lesions. Postoperatively, children with cyanotic lesions showed a deterioration in performance and achieved significantly lower scores than those with acyanotic lesions. While there were significant differences between the congenital heart disease and bone marrow transplantation groups preoperatively, these were no longer apparent at follow up.

CONCLUSIONS

In contrast to previously published findings, the present results suggest that cardiac surgery does not result in early postoperative improvements in cognitive function for children with congenital heart disease. The nature of the cardiac lesion continues to affect cognitive and academic performance, even after surgery.

Cognitive development, temperament and behavior at 2 years as indicative of language development at 4 years in pre-term infants

This study focuses on the early temperamental (TTQ = toddler temperament questionnaire), behavioral (IBR = infant behavior record), and cognitive precursors of impaired language functioning in preschool-age pre-terms infants. The study group consisted of 63 pre-term infants with a mean birth weight of 1246 +/- 437 g born in 1989-1991 in the University Central Hospital of Helsinki. Children with major disabilities (CP or mental retardation) were excluded. At the age of 4 years, 22% showed impaired language function. Logistic regression analysis showed that the Bayley MDI score was the best predictor in identifying an increased risk for language impairment. Behavioral characteristics were more strongly associated with subsequent language impairment than temperament.

Längsschnittforschung zur Entwicklungsepidemiologie psychischer Störungen: Zielsetzung, Konzeption und zentrale Befunde der Mannheimer Risikokinderstudie

Zusammenfassung. Theoretischer Hintergrund: Zur Erforschung der Entwicklungsepidemiologie psychischer Störungen gilt die prospektive Untersuchung von Risikogruppen als Königsweg. Fragestellung: Beschreibung der Entwicklungsmuster von Kindern mit frühen Belastungen, Ermittlung von Risiko- und Schutzfaktoren für unterschiedliche Entwicklungsresultate und Identifikation von Mechanismen, die differentiellen Verläufen zugrunde liegen. Methode: In einer prospektiven Längsschnittstudie (mit Erhebungswellen im Alter von 0;3, 2, 4 ½, 8 und 11 Jahren) wurden die Entstehung und der Verlauf von Entwicklungs- und Verhaltensstörungen bei 384 Kindern untersucht. Organische (prä- und perinatale Komplikationen) und psychosoziale Risiken (familiäre Belastungen) wurden in einem zwei-faktoriellen Design variiert. Ergebnisse: Die negativen Folgen früher Risiken waren bis zum Schulalter nachweisbar. Während organische Risiken vor allem die motorische und kognitive Entwicklung beeinträchtigten, konzentrierten sich die Auswirkungen psychosozialer Belastungen auf kognitive und sozial-emotionale Funktionen. Beide Risiken addierten sich in ihren negativen Konsequenzen. Schlussfolgerungen: Frühkindliche Risiken haben spezifische und langfristige Auswirkungen. Kinder mit multiplen Risikobelastungen sind in ihrer Entwicklung am stärksten gefährdet.

Follow-up of very low birthweight babies to adolescence

Reports on the school-age outcomes and behavioural difficulties at adolescence of infants who were very low birthweight (VLBW) are only just emerging. Studies which compare VLBW with same age controls consistently show significantly poorer performance, with average scores between 8 and 13 points lower. Even children with no neurological impairments have scores which are significantly lower on cognitive and achievement measures. The extremely low birthweight (ELBW) adolescents fare worse on all measures and perform particularly poorly in mathematics. A high proportion of VLBW adolescents (15%-20%), and an even higher proportion of ELBW adolescents (30%-50%), are receiving remedial assistance and/or have failed a grade. There are conflicting reports on whether the behavioural problems increase or improve with age, but most studies show that at adolescence the problems are still significantly greater in the VLBW cohort than in their peers. Methodologically rigorous studies of the current survivors to school-age should be conducted to determine whether the technological innovations in the 1990s have contributed to a reduction in psychoeducational and behavioural difficulties. Future research should also be directed towards early identification of school difficulties and development of intervention strategies targeted to the most vulnerable infants.

Entwicklung von Risikokindern im Schulalter: Die langfristigen Folgen frühkindlicher Belastungen

Zusammenfassung. Die vorliegende Untersuchung befaßt sich mit den Auswirkungen frühkindlicher Risiken auf die Entwicklung im Grundschulalter. In einer prospektiven Studie wird die motorische, kognitive und sozial-emotionale Entwicklung von 347 Kindern mit unterschiedlichen organischen und psychosozialen Risikobelastungen von der Geburt bis zum Alter von 8 Jahren in vier Erhebungswellen erfaßt. Organische Risiken (Schwangerschafts- und Geburtskomplikationen) und psychosoziale Risiken (benachteiligte familiäre Lebensumstände) werden in drei Stufen variiert und in einem zweifaktoriellen Design vollständig kombiniert. Die Ergebnisse zeigen, daß die negativen Folgen früher Risiken bis ins Schulalter fortdauern. Sowohl organisch als auch psychosozial belastete Kinder weisen im Alter von 8 Jahren ungünstigere Entwicklungskennwerte auf. Während prä- und perinatale Komplikationen vor allem die motorische und kognitive Entwicklung beeinträchtigen, konzentrieren sich die Auswirkungen familiärer Belastungen im Bereich kognitiver und sozial-emotionaler Funktionen. Beide Risiken addieren sich in ihren negativen Konsequenzen, so daß multipel belastete Kinder die größten Entwicklungsbeeinträchtigungen zeigen.

Effect of genotype on changes in intelligence quotient after dietary relaxation in phenylketonuria and hyperphenylalaninaemia

BACKGROUND

Associations between genotype and intellectual outcome in patients with phenylketonuria are complicated because intelligence is influenced by many variables, including environmental factors and other genetic determinants. Intellectual changes with age, both on and after relaxation of diet, vary within the patient population. This study aims to determine whether a significant association exists between genotype and change in intelligence after relaxation of diet.

METHODS

125 patients with hyperphenylalaninaemia and phenylketonuria whose diet was relaxed after 8 years of age. Verbal, performance, and full scale intelligence quotients at 8, 14, and 18 years were expressed as standard deviation scores (IQ-SDS), and genotype as predicted residual enzyme activity (PRA) of phenylalanine hydroxylase.

RESULTS

IQ-SDS at 8, 14, and 18 years were significantly below normal; no association was found between PRA and IQ-SDS. Significant reductions in verbal and full scale IQ-SDS occurred between 8 and 14 years and 8 and 18 years. There was a significant association between PRA and the reduction in verbal, performance, and full scale IQ between these years. Multiple regression analysis of 18 year results, using 8 year results as covariates, supported the association between PRA and IQ-SDS; after adjustment for phenylalanine control, both up to and after the age of 8 years, the full scale IQ-SDS at 14 and 18 years was 0.15 higher for each 10% increase in PRA.

CONCLUSIONS

Genotype might be useful in predicting the likelihood of intellectual change in patients with hyperphenylalaninaemia and phenylketonuria whose diet is relaxed after the age of 8 years.

Long-term follow-up following bone marrow transplantation for Hunter disease

Bone marrow transplantation (BMT) was performed in 10 patients with Hunter disease (mucopolysaccharidosis type II, iduronate-2-sulphatase deficiency). The donor was an HLA-identical sibling in 2 cases, an HLA-nonidentical relative in 6 cases, a volunteer unrelated donor in 1 case, and details were not available in 1 case. Only three patients have survived for more than 7 years post BMT; however, this high mortality probably resulted from poor donor selection. In two, there has been a steady progression of physical disability and mental handicap. One patient has maintained normal intellectual development, with only mild physical disability. It is possible that BMT may be useful in selected patients with MPS II.

Developmental outcome of infants born with biological and psychosocial risks

The significance of prenatal and perinatal complications (biological risk) and of family adversity (psychosocial risk) on early child development was examined in a prospective study. Developmental outcome of 350 infants was assessed by measures of motor, cognitive, and social-emotional functioning at 3, 24, and 54 months. Results indicated a differential impact of risk factors on specific outcomes. Whereas psychosocial risks became more prominent with growing age and were related to poorer child outcome in all areas of functioning, biological risks decreased in influence and predominantly resulted in poorer motor development. The contributions of biological and psychosocial risks on outcomes were additive. A number of individual risk factors emerged as significant predictors of later maladaptation.

The intellectual functioning of adolescents with anorexia nervosa and bulimia nervosa

The aim of this study was to investigate the intellectual functioning of a large group of eating disordered adolescents in order to test two hypotheses, viz, that the intellectual functioning of eating disordered adolescents conforms to the normal distribution, and that eating disordered adolescents do not perform better in verbal abilities than in nonverbal abilities. Standard intelligence tests were applied to 190 consecutive out- and inpatients with eating disorder diagnoses. The results were compared with those of a group of patients with other disorders, similar in age, sex, SES, and year of admission. The IQ of the eating disordered patients was significantly higher than that of patients in the comparison group. Patients in the comparison group and bulimic patients, but not anorexic patients, showed better nonverbal than verbal intellectual performance.

A family study of autism: cognitive patterns and levels in parents and siblings

First-degree relatives of 99 autism probands and of 36 Down's syndrome controls were assessed with standardised tests of intellectual functioning, reading, and spelling. Higher mean verbal IQ scores, and discrepancies in favour of verbal scores, were characteristic of autism relatives. No consistent differences were found on performance scales, reading, and spelling tests. Among autism relatives, siblings affected with the broad phenotype of autism had significantly lower IQ scores and poorer reading and spelling performances than unaffected siblings. However, the small size of the cognitive difference and the lack of a distinctive cognitive profile indicates that standardised cognitive measures used in this study are unlikely to improve the operationalised definition of the broad phenotype of autism. The slightly superior verbal performance of relatives in the autism group might represent some form of heterozygote advantage.

A longitudinal study of early intellectual development in hemiplegic children

Thirty-eight 3- to 5-year-old children with unilateral lesions sustained pre- or peri-natally were studied longitudinally over a 2-year period, and their IQ scores compared with those of 20 "medical' controls. The failure to discover laterality effects following early unilateral injury supports the hypothesis of at least broad functional equipotentiality. There were few decrements in intellectual functioning provided the injury was not accompanied by seizures. The presence of seizures in contrast had a deleterious effect on both verbal and nonverbal aspects of cognitive functioning. While the IQs of the hemiplegic groups showed considerable stability over the 2-year span of the study, there was evidence that performance IQ, even in seizure-free patients, might be selectively impaired because of competition within the intact neural space for the sparing of verbal IQ.

Bone marrow transplantation for mucopolysaccharidosis type I: experience of two British centres

Bone marrow transplantation was carried out on 38 patients with mucopolysaccharidosis type I over a period of 15 years. The donor was an HLA identical relative in 10 cases, an HLA non-identical relative in 16 cases, and an HLA identical unrelated volunteer donor in 12 cases. Ten patients received a second transplant. One patient received three transplants. Thirteen engrafted patients have survived five years or more. Most patients have shown an arrest or slowing down of psychomotor regression. However, dysostosis multiplex has progressed. Careful selection of patients may be necessary to ensure optimum results.

The changing mental health of children and adolescents: evidence for a deterioration?

This paper reviews the evidence for changing patterns of mental health over time in childhood and youth in Western societies. The evidence suggests that the prevalence of major depression, substance abuse and offending behaviour, as well as the incidence of suicide, is increasing in adolescent populations, particularly among males. There are also indications that problem behaviours among younger children are becoming more common. There is no evidence of a deterioration in the adjustment of the pre-school population.

Intellectual development of the patients of the German Collaborative Study of children treated for phenylketonuria

In a multicentric and interdisciplinary approach the German Collaborative Study of Children Treated for Phenylketonuria (PKU) investigates prospectively the effects of early started strict dietary treatment on the growth and development of 140 patients. The present paper focuses on longitudinal intelligence data from 4, 5 and 9 years of age of 89 patients in relation to the quality of dietary control in comparison to 200 healthy children tested by the same protocol. Cluster analysis of phenylalanine (Phe) levels distinguished a cluster of good dietary control with Phe levels according to the recommendation of maintaining Phe levels below 360 mumol/l, a cluster of poor dietary control with Phe levels greater than 600 mumol/l after the age of 3 years, and a cluster of intermediate control. Intelligence quotients (IQ) and Phe clusters were inversely related with non-significant differences between the clusters good and intermediate. On average, all three clusters scored significantly lower than healthy age peers. Mean IQ scores decreased for patients as well as for healthy children due to different tests used at different measurement occasions. Patients with poor dietary control showed a steeper decrease between 4 and 5 years than patients with better dietary control. Between 5 and 9 years IQ differences between patients and healthy children remained stable. Verbal IQs were higher than performance IQs for patients as well as for healthy children. It is concluded that after early and strict treatment during the pre-school years Phe levels, in the range observed, do not influence IQ development until the age of 9 years. IQ subscale pattern indicate that PKU results in a generalized reduction of IQ instead of disturbing specific abilities. It remains to be investigated whether higher Phe levels are also innocuous and/or may result in late effects.

The North American Maternal Phenylketonuria Collaborative Study, developmental assessment of the offspring: preliminary report

Preliminary results of 2-year Bayley and 4-year McCarthy test scores are presented. To date numbers are too small to statistically correlate:- offspring from pregnancies in which diet was started prior to conception, offspring from pregnancies with phenylalanine (Phe) levels of 120-360 mumol/l versus 360-600 mumol/l, influence of home environment, influence of maternal nutrition, language development, behaviour/hyperactivity, Revised Wechsler Intelligence Score, school performance and learning disabilities. Two-year Bayley scores (mental and motor) revealed a median developmental quotient of 113 in 58 offspring from control pregnancies, 104 in 19 offspring from untreated "non-phenylketonuria (PKU) mild hyperphenylalaninaemia" (natural Phe levels < 600 mumol/l) pregnancies, 104 in 32 offspring from pregnancies whose Phe levels decreased on treatment to < 600 mumol/l by 10 weeks gestation and remained in that range for the remainder of the pregnancy, 98 in offspring from 32 pregnancies where permanent control was not achieved until 10-20 weeks and 72 in offspring from 51 pregnancies where control was not attained until after 20 weeks gestation. IQ scores determined by the McCarthy test at age 4-5 years revealed a mean of 112 in 43 offspring of control mothers, 99 in 12 offspring of "non PKU mild hyperphenylalaninaemia" women, 93 in 14 offspring whose mother's Phe levels were continuously under 600 mumol/l by 10 weeks gestation, 88 in 24 offspring from pregnancies in metabolic control by 10-20 weeks and 73 in 28 offspring of pregnancies not in metabolic control until after 20 weeks gestation. These preliminary results suggest that early and adequate dietary treatment during pregnancy in maternal PKU may provide some protection to the fetus for later intellectual development but much more data is required before definitive statements about cognition can be made.

Intellectual performance after presymptomatic cranial radiotherapy for leukaemia: effects of age and sex

Cognitive outcome, as measured by verbal and performance IQs, was compared in 35 girls and 47 boys who were in first remission for acute lymphoblastic leukaemia. All children had received presymptomatic cranial radiotherapy and intrathecal methotrexate. The mean age at diagnosis was 4.2 years and the mean elapsed time from initial diagnosis to intellectual assessment was 7.1 years. Results showed that children irradiated before the age of 4 years were impaired in certain aspects of non-verbal ability, as well as in measures of short term memory and attention, calculated by factor scores derived from selected subtests of the IQ test. Subtests requiring verbal and non-verbal reasoning showed the greatest impairment after early diagnosis and treatment. In addition girls were selectively impaired in verbal IQ and other aspects of verbal ability, with the degree of impairment exacerbated by early treatment. No relationship was found between degree of impairment and either time since treatment or number of methotrexate injections. It is concluded that early age at irradiation increases the risk of impaired intellectual outcome, particularly in girls.

The relationship between normal variation in IQ and common childhood psychopathology: a clinical study

The relationship between normal variation in IQ and common psychopathology was examined in a sample of 339 5- to 16-year-olds who were seen at a tertiary psychiatric clinic. The mean IQ was 9.6 points lower (95% CI 5.5 to 13.6 points lower) for conduct than for emotional disorders, with mixed disorders in between. For these common disorders, the mean IQ was 6.0 points lower (95% CI 1.6 to 10.3 points lower) for females than males. IQ variation in the normal range was inversely related to a dimensional measure of conduct problems - an association that was not attributable to social class or mediated by scholastic attainments. Other dimensional measures of psychopathology - covering emotional symptoms, developmental immaturity and relationship difficulties - were not significantly correlated with IQ. Limitations of the study are discussed in the paper.

Relation between neurodevelopmental status of very preterm infants at one and eight years

The relation between neurodevelopmental status at one and eight years of age was investigated in a cohort of 207 infants born between 1979 and 1982 at < 33 weeks of gestation. The probability of a major disabling impairment at eight years was only 1 per cent among 164 children with normal neurodevelopment at one year, but 56 per cent for the 43 impaired children and 92 per cent for the 23 of these who had major disabling impairments. Close correspondence was found between the type of major impairment diagnosed at one and eight years. Neurodevelopmental status at one year also predicted the need for extra educational provision by eight years, with probabilities of 9 per cent for children without impairment at one year, 56 per cent for impaired children and 87 per cent for those with major impairments. Similarly, neurodevelopmental status predicted an IQ of more than 2 SD below the mean (< 70), with probabilities of 0, 30 per cent and 48 per cent, respectively.

The cognitive outcome of very preterm infants may be poorer than often reported: an empirical investigation of how methodological issues make a big difference

The effects of relying on outmoded IQ-test norms and the use of arbitrary classifications of developmental delay on estimates of cognitive impairment of very preterm infants (VPI) was evaluated in a prospective population study. Cognitive assessments included the Griffiths test at 5 and 20 months and the Columbia Mental Maturity Scales (CMM) and a vocabulary test (Aktiver Wortschatz Test, AWST) at 56 months of age. Rates of cognitive impairment of 321 very preterm infants (VPI; < 32 weeks gestation or < 1500 g birth weight) were determined according to the published test norms, to scores of a full-term control group (FC n = 321), and to scores from a representative sample of children (NC n = 431) of the same birth cohort. IQ-scores were higher in the FC and NC children than in the original standardisation sample (SS). Using the concurrent test norms (FC, NC) up to 2.4 times more VPI were identified as seriously impaired (<-2 SD) than if the published (outdated) norms were used. Serious developmental delay was underestimated when arbitrary (e.g. DQ < 70) rather than across age comparable definitions (DQ <-2 SD) were used. VPI study drop-outs had mothers with lower educational qualifications and poorer cognitive developmental scores at 5 or 20 months of age. In conclusion, a lack of appropriate control groups and use of arbitrary criteria for judging serious delay leads to large underestimations of cognitive impairment in VPI. Findings from previous uncontrolled studies of VPI need re-interpretation.

Relation between biochemical severity and intelligence in early treated congenital hypothyroidism: a threshold effect

OBJECTIVES

To assess whether early treatment of congenital hypothyroidism fully prevents intellectual impairment.

DESIGN

A national register of children with congenital hypothyroidism who were compared with unaffected children from the same school classes and matched for age, sex, social class, and first language.

SETTING

First three years (1982-4) of a neonatal screening programme in England, Wales, and Northern Ireland.

SUBJECTS

361 children with congenital hypothyroidism given early treatment and 315 control children.

MAIN OUTCOME MEASURES

Intelligence quotient (IQ) measured at school entry at 5 years of age with the Wechsler preschool and primary scale of intelligence.

RESULTS

There was a discontinuous relation between IQ and plasma thyroxine concentration at diagnosis, with a threshold at 42.8 nmol/l (95% confidence interval 35.2 to 47.1 nmol/l). Hypothyroid children with thyroxine values below 42.8 nmol/l had a mean IQ 10.3 points (6.9 to 13.7 points) lower than those with higher values and than controls. None of the measures of quality of treatment (age at start of treatment (range 1-173 days), average thyroxine dose (12-76 micrograms in the first year), average thyroxine concentration during treatment (79-234 nmol/l in the first year), and thyroxine concentration less than 103 nmol/l at least once during the first year) influenced IQ at age 5.

CONCLUSIONS

Despite early treatment in congenital hypothyroidism the disease severity has a threshold effect on brain development, probably determined prenatally. The 55% of infants with more severe disease continue to show clinically significant intellectual impairment; infants with milder disease show no such impairment. The findings predict that 10% of early treated infants with severe hypothyroidism, compared with around 40% of those who presented with symptoms in the period before screening began, are likely to require special education.

Relation between ultrasound appearance of the brain of very preterm infants and neurodevelopmental impairment at eight years

The relation between the ultrasound appearance of the brain and neurodevelopmental outcome at eight years of age was investigated in 206 infants born between 1979 and 1982 at < 33 weeks gestation (600 to 2500g birthweights). Only 4 per cent of the 112 infants with normal scans at discharge from the neonatal unit developed major, disabling impairment. No significant adverse effect of uncomplicated periventricular haemorrhage was detected. The probability of a major impairment in infants with ventricular dilatation or hydrocephalus was 27 per cent, and 69 per cent in those with cerebral atrophy. 44 per cent of the children demonstrated significant differences in their cognitive processing skills, which appeared capable of affecting learning and may possibly have been caused by undetected hypoxic-ischaemic damage to callosal fibres.