The Importance of Childhood for Adult Health and Development-Study Protocol of the Zurich Longitudinal Studies.

Evidence is accumulating that individual and environmental factors in childhood and adolescence should be considered when investigating adult health and aging-related processes. The data required for this is gathered by comprehensive long-term longitudinal studies. This article describes the protocol of the Zurich Longitudinal Studies (ZLS), a set of three comprehensive cohort studies on child growth, health, and development that are currently expanding into adulthood. Between 1954 and 1961, 445 healthy infants were enrolled in the first ZLS cohort. Their physical, motor, cognitive, and social development and their environment were assessed comprehensively across childhood, adolescence, and into young adulthood. In the 1970s, two further cohorts were added to the ZLS and assessed with largely matched study protocols: Between 1974 and 1979, the second ZLS cohort included 265 infants (103 term-born and 162 preterm infants), and between 1970 and 2002, the third ZLS cohort included 327 children of participants of the first ZLS cohort. Since 2019, the participants of the three ZLS cohorts have been traced and invited to participate in a first wave of assessments in adulthood to investigate their current health and development. This article describes the ZLS study protocol and discusses opportunities, methodological and conceptual challenges, and limitations arising from a long-term longitudinal cohort recruited from a study about development in early life. In the future, the ZLS will provide data to investigate childhood antecedents of adult health outcomes and, ultimately, will help respond to the frequent call of scientists to shift the focus of aging research into the first decades of life and, thus, to take a lifespan perspective on aging.

A quick and qualitative assessment of gross motor development in preschool children.

There is a need for a quick, qualitative, reliable, and easy tool to assess gross motor development for practitioners. The aim of this cross-sectional study is to present the Zurich Neuromotor Assessment-Q (ZNA-Q), which assesses static and dynamic balance in children between 3 and 6 years of age in less than 5 min. A total of 216 children (103 boys; 113 girls; median age 4 years, 4 months; interquartile range 1 year, 3 months) were enrolled from day-care centers, kindergartens, and schools, and were tested with 5 different gross motor tasks: standing on one leg, tandem stance, hopping on one leg, walking on a straight line, and jumping sideways. All ordinal measures (consisting of qualitative measures and scales) featured a marked developmental trend and substantial inter-individual variability. Test-retest reliability was assessed on 37 children. It varied from .17 for tandem stance to .43 for jumping sideways for the individual tasks, and it was .41 and .67 for the static and dynamic balance components, respectively. For the whole ZNA-Q, test-retest reliability was .7.Conclusion: Ordinal scales enable practitioners to gather data on children's gross motor development in a fast and uncomplicated way. It offers the practitioner with an instrument for the exploration of the current developmental motor status of the child. What is Known: • Measurement of gross motor skills in the transitional period between motor mile stones and quantitative assessments is difficult. • Assessment of gross motor skills is relatively easy. What is New: • Supplementary and quick gross motor test battery for children for practitioners. • Normative values of five gross motor skills measured with ordinal scales.

Neuromotor development in children. Part 4: new norms from 3 to 18 years.

AIM: The aim of this cross-sectional study was to provide normative data for motor proficiency (motor performance and contralateral associated movements [CAMs]) in typically developing children between 3 years and 18 years of age using an updated version of the Zurich Neuromotor Assessment (ZNA-2). METHOD: Six-hundred and sixteen typically developing children between 3 years and 18 years of age were enrolled from day-care centres, kindergartens, and schools, and were tested using the ZNA-2 with improved items of the original battery. Motor proficiency was assessed on five components (fine motor tasks, pure motor tasks, static balance, dynamic balance, and CAMs) as a function of age and sex to determine centile curves for each task. Intraobserver, interobserver, and test-retest reliabilities were evaluated. RESULTS: Most ZNA-2 tasks featured a marked developmental trend and substantial interindividual variability. Test-retest reliability was generally high (e.g. static balance 0.67; CAMs 0.81; and total scores 0.84). INTERPRETATION: The ZNA-2 is a reliable and updated test instrument to measure motor proficiency in children from 3 to 18 years with improved properties for assessing motor performance. It allows continuous measurement without changing items for the entire age range; this feature of the ZNA-2 is unique and makes the instrument suitable for clinical purposes. The reduction of CAMs scoring simplifies the clinical procedure and increases its reliability. WHAT THIS PAPER ADDS: The Zurich Neuromotor Assessment, Second Edition (ZNA-2) provides new norms for motor proficiency in children between 3 years and 18 years. High reliabilities suggest that the revised test battery is a useful tool for assessing neuromotor development. Integration of a 'not able to perform' category makes the ZNA-2 suitable for clinical purposes.

Similarities and dissimilarities between the movement ABC-2 and the Zurich neuromotor assessment in children with suspected developmental coordination disorder.

An established tool for the assessment of motor performance in children with developmental coordination disorder (DCD) is the Movement-ABC-2 (M-ABC-2). The Zurich Neuromotor Assessment (ZNA) is also widely used for the evaluation of children's motor performance, but has not been compared with the M-ABC-2. Fifty-one children (39 males) between 5 and 7 years of age with suspected DCD were assessed using the M-ABC-2 and the ZNA. Rank correlations between scores of different test components were calculated. The structure of the tests was explored using canonical-correlation analysis. The correlation between total scores of the two motor tests was reasonable (0.66; p<0.001). However, ZNA scores were generally lower than those of M-ABC-2, due to poor performance in the fine motor adaptive component and increased contralateral associated movements (CAM). The canonical-correlation analysis revealed that ZNA measures components like pure motor skills and CAM that are not represented in the M-ABC-2. Furthermore, there was also no equivalent for the aiming and catching items of the M-ABC-2 in ZNA. The two tests measure different motor characteristics in children with suspected DCD and, thus, can be used complementary for the diagnosis of the disorder.

Neuromotor development in children. Part 3: motor performance in 3- to 5-year-olds.

AIM: The aim of this cross-sectional study was to provide normative data (ordinal scores and timed performances) for gross and fine motor tasks in typically developing children between 3 and 5 years of age using the Zurich Neuromotor Assessment (ZNA). METHOD: Typically developing children (n=101; 48 males, 53 females) between 3 and 5 years of age were enrolled from day-care centres in the greater Zurich area and tested using a modified version of the ZNA; the tests were recorded digitally on video. Intraobserver reliability was assessed on the videos of 20 children by one examiner. Interobserver reliability was assessed by two examiners. Test-retest reliability was performed on an additional 20 children. The modelling approach summarized the data with a linear age effect and an additive term for sex, while incorporating informative missing data in the normative values. Normative data for adaptive motor tasks, pure motor tasks, and static and dynamic balance were calculated with centile curves (for timed performance) and expected ordinal scores (for ordinal scales). RESULTS: Interobserver, intraobserver, and test-retest reliability of tasks were moderate to good. Nearly all tasks showed significant age effects, whereas sex was significant only for stringing beads and hopping on one leg. INTERPRETATION: These results indicate that timed performance and ordinal scales of neuromotor tasks can be reliably measured in preschool children and are characterized by developmental change and high interindividual variability.

Children with congenital hypothyroidism: long-term intellectual outcome after early high-dose treatment.

We aim to determine long-term intellectual outcome of adolescents with early high-dose treated congenital hypothyroidism (CH). Sixty-three prospectively followed children with CH were assessed at age of 14 y with the Wechsler Intelligence Scale for Children-Revised and compared with 175 healthy controls. Median age at onset of treatment was 9 d (range 5-18 d) and median starting dose of levothyroxine (L-T4) was 14.7 microg/kg/d (range 9.9-23.6 microg/kg/d). Full-scale intelligence quotient (IQ) was significantly lower than in controls after adjustment for socioeconomic status (SES) and gender (101.7 versus 111.4; p < 0.0001). Children with athyreosis had a lower performance IQ than those with dysgenesis (adjusted difference 7.6 IQ scores, p < 0.05). Lower initial thyroxine (T4) levels correlated with poorer IQ (r = 0.27, p = 0.04). Lower SES was associated with poorer IQ, in particular in children with CH (interaction, p = 0.03). Treatment during childhood was not related to IQ at age 14 y. Adolescents with CH manifest IQ deficits when compared with their peers despite early high-dose treatment and optimal substitution therapy throughout childhood. Those adolescents with athyreosis and lower SES are at particular risk for adverse outcome. Therefore, early detection of intellectual deficits is mandatory in children with CH.

Sleep duration from ages 1 to 10 years: variability and stability in comparison with growth.

OBJECTIVE: Our goal was to describe the variability of sleep duration (time in bed per 24 hours) in healthy children from 1 to 10 years of age in comparison with growth measures. METHODS: A total of 305 children were followed with structured sleep-related interviews and measurements of height and weight 12, 18, and 24 months after birth and then at annual intervals until 10 years of age. SD scores were calculated, and smooth curves were fitted by smoothing splines through the SD scores. The long-term variability channel within children (units SD score) was defined as the difference between the maximum and the minimum of the smooth curves and the short-term variability channel (units SD score) as the difference of the largest and the smallest deviations of the original SD scores from the smooth curve. RESULTS: Sleep duration remained within a long-term variability channel <0.5 SD score in 21% of the children (34% for height, 21% for weight). Nearly every second child (46%) stayed within a long-term variability channel <1.0 SD score (76% for height, 64% for weight). Sleep duration of approximately 90% of all children ran within a long-term variability channel of <2.0 SD score (corresponding, eg, to the range between the 2nd and the 50th percentile). No single child's sleep duration remained within a short-term variability channel <0.5 SD score, indicating fluctuations from year to year (60% for height, 53% for weight). An association between aspects of sleep duration and somatic growth was not observed at any age. CONCLUSIONS: Sleep duration during early and middle childhood shows large variability among children, as well as trait-like long-term stability and state-like yearly fluctuations within children. An individual approach to the child's sleep behavior is needed; expectations in terms of appropriate sleep duration of the child should be adjusted to the individual sleep need.

Sleep behaviour in preterm children from birth to age 10 years: a longitudinal study.

AIM: To study clinically relevant aspects of sleep behaviour in preterm children in comparison to term children. METHODS: Longitudinal sleep behaviour data were collected prospectively by structured interviews in 130 preterm and 75 control term children from birth to age 10 y. RESULTS: No significant differences in sleep duration (time in bed per 24 h), bedsharing, night wakings, bedtime resistance and sleep-onset difficulties were found between preterm and term children. CONCLUSION: Sleep behaviour does not differ between preterm and term children from birth to age 10 y, indicating that prematurity or neonatal intensive care experience does not significantly affect sleep in the first 10 y of life.

Impaired motor performance and movement quality in very-low-birthweight children at 6 years of age.

Motor performance and movement quality were quantitatively examined (Zurich Neuromotor Assessment: timed motor performances and associated movements) in 87 prospectively enrolled very-low-birthweight (VLBW; <1250g) children (38 males, 49 females; mean birthweight 1016.2g [SD 141.5]:, range 720-1240g; mean gestational age 28.7wks [SD 2], range 25.7-33.4wks) at 6 years of age. All motor tasks were below the reference population: pure motor (median z-score) -0.46; adaptive fine motor (pegboard) -0.99; adaptive gross motor -0.88; static balance -0.48; and associated movements -1.90. All tasks correlated with the degree of neurological abnormalities (p

Contribution of proton magnetic resonance spectroscopy to the evaluation of children with unexplained developmental delay.

Developmental delay (DD) in children is a common socioeconomic problem with a prevalence of 1-2%. The cause of DD in children is often unknown, and magnetic resonance imaging plays an important role in evaluating children with DD, estimating long-term prognosis, and guiding therapeutic options. The aim of our study on children with DD was to elucidate 1) whether magnetic resonance spectroscopy (MRS) reveals abnormalities in cerebral metabolism and 2) whether there is a correlation between the cognitive performance and the concentration of brain metabolites, especially N-acetylaspartate (NAA), named in the literature a neuronal marker. Using proton MRS of deep gray and central white matter, we measured concentrations of brain metabolites in 48 children, who were aged 1 mo to 13 y and had unexplained DD [developmental quotient (DQ) between <50 and 85] and normal magnetic resonance imaging examinations, and compared them with those of 23 age-matched normal control children. Children with DD were divided into three groups: mild (DQ 76-85), moderate (DQ 51-75), and severe (DQ <50). We found no significant differences in metabolite concentrations, neither among the three groups of children with DD nor between patients and age-matched normal control children. Independent of the degree of mental retardation, the NAA concentrations of handicapped patients and normal children were comparable. We conclude that 1) brain metabolites, especially NAA, in children with unexplained DD are within normal limits, and 2) in most cases, proton MRS adds little information concerning cause of unexplained DD.

A longitudinal study of bed sharing and sleep problems among Swiss children in the first 10 years of life.

OBJECTIVE: To study age trends, long-term course and secular changes of bed-sharing practices, and sleep problems among Swiss families. METHODS: A total of 493 children were longitudinally followed between 1974 and 2001 by using structured sleep-related interviews at 1, 3, 6, 9, 12, 18, and 24 months after birth and at annual intervals thereafter until 10 years of age. Parents were queried about bed sharing, night wakings, bedtime resistance, and sleep-onset difficulties during the 3 months before each follow-up interview. RESULTS: Although in the first year of life relatively few children slept with their parents (<10%), bed sharing increased with age and reached a maximum at 4 years (> or =1 times per week: 38%). Bed sharing of at least once per week was noted in 44% of the children between 2 and 7 years old. Nocturnal wakings also increased from 6 months old to a maximum at 4 years, when more than half of all children woke up at least once per week (22% every night at 3 years). Less than 10% of all children demonstrated frequent bedtime resistance and sleep-onset difficulties. Bed sharing and night wakings during early infancy were not predictive for bed sharing or night wakings during childhood, whereas both bed sharing and night wakings during childhood tended to persist over time. In contrast, bedtime resistance and sleep-onset difficulties seemed to be rather transient phenomena across all ages. No consistent cohort trends were found except for bedtime resistance, which decreased significantly between 1974 and 2001. CONCLUSIONS: Bed sharing and nocturnal wakings are common during early childhood. Developmental changes in separation-attachment processes, cognitive capabilities to develop self-recognition and nighttime fears, and motor locomotion may contribute to the particular age trend of night wakings and bed sharing during early childhood.

Improved outcome for very low birth weight multiple births.

This study describes time trends for very low birth weight multiple births in relation to very low birth weight singletons. Two cohorts of very low birth weight (less than 1250 gm) children recruited between 1983-85 (cohort 1, n = 115) and 1992-94 (cohort 2, n = 144) were compared. The Bayley Scales of Infant Development and a standardized neurologic examination were administered at 2 years corrected age. Neurodevelopmental outcome did not change between cohort 1 and 2 for singletons. For multiple births, mean Mental Developmental Index increased after adjustment for neonatal risk factors [adjusted mean (standard deviation) 81.8 (11.7) to 96.5 (18.6), analysis of covariance P = 0.007]. The prevalence of cerebral palsy decreased, however not significantly [adjusted odds ratio (95% confidence interval) 0.3 (0.1-1.5), P = 0.14]. The proportion of disease-free survival (no cerebral palsy and no developmental delay) increased for multiple births (7-37%, P = 0.002), but not for singletons. In cohort 2, neurodevelopmental outcome of multiple births was similar to that of singletons. The cognitive outcome of very low birth weight multiple births improved, possibly because of changes in perinatal practice. However, neurodevelopmental outcome was similar to that of very low birth weight singletons who were unaffected by changes in neonatal care with high proportions of motor delay and cerebral palsy.

Postnatal growth in VLBW infants: significant association with neurodevelopmental outcome.

OBJECTIVE: To study the significance of growth status at birth and postnatal growth on neurodevelopmental outcome in very low birth weight (VLBW) infants. STUDY DESIGN: Growth and neurodevelopment were examined in 219 VLBW (<1250 g) children, 94 small for gestational age (SGA) (<10th percentile) and 125 appropriate for gestational age (AGA) (>10th percentile). Outcome at age 2 was assessed with the Bayley Scales of Infant Development (Mental Developmental Index [MDI], Psychomotor Developmental Index [PDI]) and a standardized neurologic examination. RESULTS: SGA status was not associated with poor neurodevelopmental outcome. However, after adjustment for covariables including cerebral palsy (CP), SGA children with weight <10th percentile at age 2 had lower mean PDI than SGA children with catch-up growth to weight >10th percentile (mean [SD], 89.9 [17.4] versus 101.8 [14.5]; P<.001). AGA children with catch-down growth (weight <10th percentile at age 2) were, independent of CP, more likely to have lower mean MDI (94.9 vs 101.7, P=.05) and PDI (81.9 vs 95.1; P<.001) than AGA children remaining >10th percentile at age 2. They also more frequently had severe CP (22.9% vs 1.2%; P=.008). CONCLUSIONS: In VLBW children, the course of postnatal growth rather than the appropriateness of weight for gestational age at birth determines later neurodevelopmental outcome.

Sleep duration from infancy to adolescence: reference values and generational trends.

OBJECTIVE: The main purpose of the present study was to calculate percentile curves for total sleep duration per 24 hours, for nighttime and for daytime sleep duration from early infancy to late adolescence to illustrate the developmental course and age-specific variability of these variables among subjects. METHODS: A total of 493 subjects from the Zurich Longitudinal Studies were followed using structured sleep-related questionnaires at 1, 3, 6, 9, 12, 18, and 24 months after birth and then at annual intervals until 16 years of age. Gaussian percentiles for ages 3 months to 16 years were calculated for total sleep duration (time in bed) and nighttime and daytime sleep duration. The mean sleep duration for ages 1 to 16 years was estimated by generalized additive models based on the loess smoother; a cohort effect also had to be included. The standard deviation (SD) was estimated from the loess smoothed absolute residuals from the mean curve. For ages 3, 6, and 9 months, an alternative approach with a simple model linear in age was used. For age 1 month, empirical percentiles were calculated. RESULTS: Total sleep duration decreased from an average of 14.2 hours (SD: 1.9 hours) at 6 months of age to an average of 8.1 hours (SD: 0.8 hours) at 16 years of age. The variance showed the same declining trend: the interquartile range at 6 months after birth was 2.5 hours, whereas at 16 years of age, it was only 1.0 hours. Total sleep duration decreased across the studied cohorts (1974-1993) because of increasingly later bedtime but unchanged wake time across decades. Consolidation of nocturnal sleep occurred during the first 12 months after birth with a decreasing trend of daytime sleep. This resulted in a small increase of nighttime sleep duration by 1 year of age (mean 11.0 +/- 1.1 hours at 1 month to 11.7 +/- 1.0 hours at 1 year of age). The most prominent decline in napping habits occurred between 1.5 years of age (96.4% of all children) and 4 years of age (35.4%). CONCLUSIONS: Percentile curves provide valuable information on developmental course and age-specific variability of sleep duration for the health care professional who deals with sleep problems in pediatric practice.