Systematic assessment of perinatal and socio-demographic factors associated with IQ from childhood to adult life following very preterm birth

Are perinatal measures associated with adolescent mental health? A retrospective exploration with original data from psychiatric cohorts

BACKGROUND

Perinatal markers of prenatal development are associated with offspring psychiatric symptoms. However, there is little research investigating the specificity of perinatal markers for the development of specific disorders. This study aimed to explore if perinatal markers are specifically associated with adolescent substance use disorder (SUDs).

METHODS

Adolescent participants from two study centers, one for SUD patients (n = 196) and one for general psychopathology (n = 307), were recruited for participation. Since the SUD participants presented with a number of comorbid disorders, we performed a 1-on-1 matching procedure, based on age, gender, and specific pattern of comorbid disorders. This procedure resulted in n = 51 participants from each group. From all participants and their mothers we recorded perinatal markers (mode of birth, weeks of completed pregnancy, birth weight, Apgar score after 5 min) as well as intelligence quotient (IQ). The SUD sample additionally filled out the Youth Safe Report (YSR) as well as the PQ-16 and the DUDIT. We aimed to distinguish the two groups (SUD sample vs. general psychiatric sample) based on the perinatal variables via a logistic regression analysis. Additionally, linear regressions were performed for the total group and the subgroups to assess the relationship between perinatal variables and IQ, YSR, DUDIT and PQ-16.

RESULTS

The perinatal variables were not able to predict group membership (X² [4] = 4.77, p = .312, Cox & Snell R² = 0.053). Odds ratios indicated a small increase in probability to belonging to the general psychiatric sample instead of the SUD sample if birth was completed via C-section. After Bonferroni-correction, the linear regression models showed no relation between perinatal markers and IQ (p = .60, R² = 0.068), YSR (p = .09, R² = 0.121), DUDIT (p = .65, R² = 0.020), and PQ-16 (p = .73, R² =0.021).

CONCLUSION

Perinatal markers were not able to distinguish SUD patients from patients with diverse psychopathologies. This pattern contradicts previous findings, perhaps because our chosen markers reflect general processes instead of specific mechanistic explanations. Future studies should take care to investigate specific prenatal markers and associate them with psychopathology on the symptom level.

Adult outcome of preterm birth: Implications for neurodevelopmental theories of psychosis

Preterm birth is associated with an elevated risk of developmental and adult psychiatric disorders, including psychosis. In this review, we evaluate the implications of neurodevelopmental, cognitive, motor, and social sequelae of preterm birth for developing psychosis, with an emphasis on outcomes observed in adulthood. Abnormal brain development precipitated by early exposure to the extra-uterine environment, and exacerbated by neuroinflammation, neonatal brain injury, and genetic vulnerability, can result in alterations of brain structure and function persisting into adulthood. These alterations, including abnormal regional brain volumes and white matter macro- and micro-structure, can critically impair functional (e.g. frontoparietal and thalamocortical) network connectivity in a manner characteristic of psychotic illness. The resulting executive, social, and motor dysfunctions may constitute the basis for behavioural vulnerability ultimately giving rise to psychotic symptomatology. There are many pathways to psychosis, but elucidating more precisely the mechanisms whereby preterm birth increases risk may shed light on that route consequent upon early neurodevelopmental insult.

Toddler motor performance and intelligence at school age in preterm born children: A longitudinal cohort study

BACKGROUND

Current knowledge regarding differences in verbal intelligence scores (VIQ) and performance intelligence scores (PIQ) in preterm born children is limited. As early motor performance may be essential for developing later visual-perceptual and visual-motor skills, early motor performance may be associated with PIQ.

AIMS

To evaluate whether in preterm born children motor performance at two years was associated with PIQ at eight years.

METHODS

Single-centre cohort study including 88 children born <30 weeks' gestation between 2007 and 2011, who completed the Bayley Scales of Infant and Toddler Development-III (BSID-III) at two years and the Wechsler Intelligence Scale for Children-III-NL (WISC-III-NL) at eight years. Outcome measurements (mean (SD)) were gross and fine motor performance based on the BSID-III, and PIQ and VIQ based on the WISC-III-NL. Linear regression analysis was performed to evaluate the association between motor performance at two years and PIQ at eight years.

RESULTS

At two years, mean BSID-III gross motor scaled score was 9.0 (SD 3.0) and fine motor score was 11.5 (SD 2.3). At eight years, mean PIQ was 94.9 (SD 13.5) and mean VIQ 101.8 (SD 13.7). A one-point increase in fine motor scaled score was associated with 1.7 points (95% CI 0.5-2.8) increase in PIQ. Gross motor scaled score was not associated with PIQ.

CONCLUSIONS

Fine motor performance in toddlerhood was related to PIQ at school age, with lower scores indicating a lower PIQ. Early assessment of fine motor performance may be beneficial in identifying children at risk for lower performance intelligence.

Association of Very Preterm Birth or Very Low Birth Weight With Intelligence in Adulthood: An Individual Participant Data Meta-analysis

IMPORTANCE

Birth before 32 weeks' gestation (very preterm [VPT]) and birth weight below 1500 g (very low birth weight [VLBW]) have been associated with lower cognitive performance in childhood. However, there are few investigations of the association of neonatal morbidities and maternal educational levels with the adult cognitive performance of individuals born VPT or VLBW (VPT/VLBW).

OBJECTIVE

To assess differences in adult IQ between VPT/VLBW and term-born individuals and to examine the association of adult IQ with cohort factors, neonatal morbidities, and maternal educational level among VPT/VLBW participants.

DATA SOURCES

Systematic review of published data from PubMed and meta-analysis of individual participant data (IPD) of cohorts from 2 consortia (Research on European Children and Adults Born Preterm [RECAP] and Adults Born Preterm International Collaboration [APIC]).

STUDY SELECTION

The meta-analysis included prospective longitudinal cohort studies that assessed the full-scale IQ of adults born VPT or VLBW and respective control groups comprising term-born adults.

DATA EXTRACTION AND SYNTHESIS

The study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline for analyses of individual participant data and identified 8 studies that provided data from 2135 adults (1068 VPT/VLBW and 1067 term-born participants) born between 1978 and 1995. Meta-analyses of IPD were performed using a 1-stage approach, treating VPT birth or VLBW and cohort as random effects.

MAIN OUTCOMES AND MEASURES

Full-scale IQ scores were converted to z scores within each cohort using the combined SD of VPT/VLBW participants and a control group of term-born participants, with scores centered on the mean of the control group.

RESULTS

A total of 426 records were identified and screened. After exclusions, 13 studies were included in the aggregate meta-analysis. The IPD meta-analysis included 8 of the 9 RECAP and APIC cohorts with adult IQ data. The mean (SD) age among the 8 IPD cohorts was 24.6 (4.3) years, and 1163 participants (54.5%) were women. In unadjusted analyses, VPT/VLBW participants had mean adult IQ scores that were 0.78 SD (95% CI, -0.90 to -0.66 SD) lower than term-born participants, equivalent to a difference of 12 IQ points. Among VPT/VLBW participants, lower gestational age (score difference per week of gestation, 0.11; 95% CI, 0.07-0.14), lower birth weight z scores (score difference per 1.0 SD, 0.21; 95% CI, 0.14-0.28), the presence of neonatal bronchopulmonary dysplasia (score difference, -0.16; 95% CI, -0.30 to -0.02) or any grade of intraventricular hemorrhage (score difference, -0.19; 95% CI, -0.33 to -0.05), and lower maternal educational level (score difference, 0.26; 95% CI, 0.17-0.35) were all significantly associated with lower IQ scores in adulthood.

CONCLUSIONS AND RELEVANCE

In this IPD meta-analysis, lower gestational age, lower weight for gestational age, neonatal morbidities, and lower maternal educational levels were all important risk factors associated with lower IQ among young adults born VPT or VLBW.