Association of preterm birth with ADHD-like cognitive impairments and additional subtle impairments in attention and arousal malleability

Neurological examination at 32-weeks postmenstrual age predicts 12-month cognitive outcomes in very preterm-born infants

BACKGROUND

To determine the diagnostic accuracy of Hammersmith Neonatal Neurological Examination (HNNE) at 30-32 weeks postmenstrual age (PMA, 'Early') and term equivalent age (TEA) in infants born <31 weeks PMA to predict cognitive outcomes at 12 months corrected age (CA).

METHODS

Prospective cohort study of 119 infants (73 males; median 28.4 weeks gestational age at birth) who underwent Early and TEA HNNE. At 12 months CA, 104 participants completed Bayley Scales of Infant and Toddler Development, 3rd Edition, (Bayley-III). Optimum cut-off points for each HNNE subscale were determined to establish diagnostic accuracy for predicting adverse cognitive outcomes on the Bayley-III Cognitive Composite Scale (≤85).

RESULTS

The best diagnostic accuracy for HNNE total score at 30-32 weeks PMA predicting cognitive impairment occurred at cut-off ≤16.7 (sensitivity (Se) = 71%, specificity (Sp) = 51%). The Abnormal Signs subscale demonstrated the best balance of sensitivity/specificity combination (Se = 71%, Sp = 71%; cut-off ≤1.5). For HNNE at TEA, the total score at cut-off ≤24.5 had Se = 71% and Sp = 47% for predicting cognitive impairment. The Tone Patterns subscale demonstrated the strongest diagnostic accuracy at TEA (Se = 71%, Sp = 63%; cut-off ≤3).

CONCLUSIONS

Early and TEA HNNE demonstrated moderate diagnostic accuracy for cognitive outcomes at 12-months CA in infants born <31 weeks gestational age.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry; Trial Registration Number: ACTRN12613000280707; web address of trial: http://www.ANZCTR.org.au/ACTRN12613000280707.aspx .

IMPACT

Early Hammersmith Neonatal Neurological Examination (HNNE) assessment at 30-32 weeks postmenstrual age has moderate diagnostic accuracy for cognitive outcomes at 12 months corrected age in infants born <31 weeks gestation. Early HNNE at 30-32 weeks has stronger predictive validity than HNNE at term equivalent age. Early HNNE may provide an early marker for risk-stratification to optimise the planning of post-discharge support and follow-up services for infants born preterm.

Adaptive Cognitive Control in Prematurely Born Children: An HD-EEG Investigation

Preterm birth is a neurodevelopmental risk condition often associated with cognitive control (CC) impairment. Recent evidence showed that CC can be implicitly adapted through associative learning. In the present study we investigated the ability to flexibly adjust CC as a function of implicit stimulus-response temporal regularities in preterm (PT; N = 21; mean age 8 ± 1.3 years; gestational age 30 ± 18.5 weeks) and full-term (FT; N = 20; mean age 8 ± 1.3 years) school-age children. All children underwent an HD-EEG recording while undergoing the Dynamic Temporal Prediction (DTP) task, a simple S1–S2 detection task purposely designed to generate local-global temporal predictability of imperative stimuli. The Wisconsin card sorting test (WCST) was administered to measure explicit CC. The PT group showed more premature and slower (DTP) as well as perseverative (WCST) responses than the FT group. Moreover, pre-terms showed poor adaptive CC as revealed by less efficient global response-speed adjustment. This behavioral pattern was mirrored by a reduced and less sensitive to global manipulation anticipatory Contingent Negative Variation (CNV) and by different cortical source recruitment. These findings suggest that implicit CC may be a reliable endophenotypic marker of atypical cognitive development associated with preterm birth.

Does Co-Occurring Anxiety Modulate ADHD-Related Cognitive and Neurophysiological Impairments?

Objective: This study investigates whether anxiety modulates cognitive-performance, electrophysiological and electrodermal processes that we previously found impaired in individuals with ADHD. Method: Self-reported anxiety symptoms, cognitive-electrophysiological measures of response inhibition, working memory, attention, conflict monitoring, error processing, and peripheral arousal during three cognitive tasks were obtained from 87 adolescents and young adults with ADHD and 169 controls. We tested the association of anxiety symptoms with each measure and whether controlling for anxiety symptoms attenuates the ADHD-control difference for each measure. Results: Individuals with ADHD showed significantly elevated anxiety symptoms compared with controls. Only commission errors on a Continuous Performance Test (measuring response inhibition) were significantly associated with anxiety symptoms and only among controls, with the ADHD-control difference in this measure remaining significant. Conclusion: Using a wide range of cognitive, electrophysiological, and electrodermal measures, our investigation suggests, overall, limited malleability of these impairments in individuals with ADHD irrespective of their levels of anxiety.

Does ADHD worsen inhibitory control in preschool children born very premature and/or with very low birth weight?

INTRODUCTION

Deficits in executive functioning, especially in inhibitory control, are present in children born very premature and/or with very low birth weight (VP/VLBW) and in children with attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

To evaluate whether ADHD imposes additional inhibitory control (IC) deficits in preschoolers born VP/VLBW.

METHODS

79 VP/VLBW (4 to 7 years) children were assessed for ADHD using the Schedule for Affective Disorders and Schizophrenia for School Aged Children - Present and Lifetime Version (K-SADS-PL). IC was measured with Conners' Kiddie Continuous Performance Test (K-CPT 2) and the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P).Results: No significant differences were found between ADHD (n = 24) and non-ADHD children (n = 55) for any of the measures (p = 0.062 to p = 0.903). Both groups had deficits in most K-CPT 2 scores compared to normative samples, indicating poor IC and inconsistent reaction times.

CONCLUSIONS

ADHD does not aggravate IC deficits in VP/VLBW children. Either neuropsychological tasks and parent reports of executive functions (EFs) may not be sensitive enough to differentiate VP/VLBW preschoolers with and without ADHD, or these children's EFs are already so impaired that there is not much room for additional impairments imposed by ADHD.

ADHD: Current Concepts and Treatments in Children and Adolescents

Attention deficit hyperactivity disorder (ADHD) is among the most frequent disorders within child and adolescent psychiatry, with a prevalence of over 5%. Nosological systems, such as the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) and the International Classification of Diseases, editions 10 and 11 (ICD-10/11) continue to define ADHD according to behavioral criteria, based on observation and on informant reports. Despite an overwhelming body of research on ADHD over the last 10 to 20 years, valid neurobiological markers or other objective criteria that may lead to unequivocal diagnostic classification are still lacking. On the contrary, the concept of ADHD seems to have become broader and more heterogeneous. Thus, the diagnosis and treatment of ADHD are still challenging for clinicians, necessitating increased reliance on their expertise and experience. The first part of this review presents an overview of the current definitions of the disorder (DSM-5, ICD-10/11). Furthermore, it discusses more controversial aspects of the construct of ADHD, including the dimensional versus categorical approach, alternative ADHD constructs, and aspects pertaining to epidemiology and prevalence. The second part focuses on comorbidities, on the difficulty of distinguishing between "primary" and "secondary" ADHD for purposes of differential diagnosis, and on clinical diagnostic procedures. In the third and most prominent part, an overview of current neurobiological concepts of ADHD is given, including neuropsychological and neurophysiological researches and summaries of current neuroimaging and genetic studies. Finally, treatment options are reviewed, including a discussion of multimodal, pharmacological, and nonpharmacological interventions and their evidence base.

Electrocardiographic features at rest and during exercise in young adults born preterm below 30 weeks of gestation

BACKGROUND

Preterm birth has adverse consequences on the cardiovascular system. Whether premature birth is associated with conduction and repolarisation abnormalities past childhood and into adulthood still needs to be demonstrated.

METHODS

We analyzed the ECG of young adults (23.9 ± 3.1 years) born term (≥37 weeks, n = 53) and preterm (<30 weeks, n = 49) at rest, peak exercise and 3 min into recovery during an exercise test on a cycle ergometer. We measured PR, QRS and QT intervals, calculated the corrected QT (QTc), and determined blood calcium, magnesium, potassium and fasting glucose.

RESULTS

Mean gestational age was 39.7 ± 1.1 and 27.3 ± 1.3 weeks for the term and the preterm groups, respectively. Apart from an increased heart rate at rest in individuals born preterm, no significant difference was found between both groups for any other ECG parameters at rest. None of the participants had a severely prolonged QTc (>500 ms) at rest; exercise revealed severely prolonged QTc in two participants including one in the preterm group. The use of QT-prolonging medications did not influence ECG parameters in either groups.

CONCLUSIONS

We observed no significant difference in electrocardiographic measurements between young adults born preterm and term. Current results do not support avoidance of QT-prolonging medications in individuals born preterm.

IMPACT

Preterm birth is associated with adverse cardiovascular consequences in early adulthood, but controversial evidence exists regarding differences in electrocardiographic features between young individuals born term and preterm.This study aims to assess the differences in electrocardiographic features between young adults born term and preterm, at rest and during exercise training.In contrast with previously published data, we observed no significant difference in electrocardiographic measurements between young adults born preterm and term.Our study does not support that preterm birth itself exposes young adults to a higher risk of QT prolongation.Current results do not support avoidance of QT-prolonging medications in individuals born preterm.

Is association of preterm birth with cognitive-neurophysiological impairments and ADHD symptoms consistent with a causal inference or due to familial confounds?

BACKGROUND

Preterm birth is associated with an increased risk for cognitive-neurophysiological impairments and attention-deficit/hyperactivity disorder (ADHD). Whether the associations are due to the preterm birth insult per se, or due to other risk factors that characterise families with preterm-born children, is largely unknown.

METHODS

We employed a within-sibling comparison design, using cognitive-performance and event-related potential (ERP) measures from 104 preterm-born adolescents and 104 of their term-born siblings. Analyses focused on ADHD symptoms and cognitive and ERP measures from a cued continuous performance test, an arrow flanker task and a reaction time task.

RESULTS

Within-sibling analyses showed that preterm birth was significantly associated with increased ADHD symptoms (β = 0.32, p = 0.01, 95% CI 0.05 to 0.58) and specific cognitive-ERP impairments, such as IQ (β = -0.20, p = 0.02, 95% CI -0.40 to -0.01), preparation-vigilance measures and measures of error processing (ranging from β = 0.71, -0.35). There was a negligible within-sibling association between preterm birth with executive control measures of inhibition (NoGo-P3, β = -0.07, p = 0.45, 95% CI -0.33 to 0.15) or verbal working memory (digit span backward, β = -0.05, p = 0.63, 95% CI -0.30 to 0.18).

CONCLUSIONS

Our results suggest that the relationship between preterm birth with ADHD symptoms and specific cognitive-neurophysiological impairments (IQ, preparation-vigilance and error processing) is independent of family-level risk and consistent with a causal inference. In contrast, our results suggest that previously observed associations between preterm birth with executive control processes of inhibition and working memory are instead linked to background characteristics of families with a preterm-born child rather than preterm birth insult per se. These findings suggest that interventions need to target both preterm-birth specific and family-level risk factors.

The Life Course Consequences of Very Preterm Birth

Around 15 million children are born preterm (<37 weeks of gestation) every year. Of these, 15% or 2.25 million are born very preterm (VP; <32 weeks of gestation). Here, the developmental outcomes of VP babies in diverse domains from motor, cognitive, and social function to mental health and well-being throughout childhood and adolescence are reviewed. Their life course adaptation in terms of romantic relationships, employment, and quality of life into adulthood is also considered. Some adverse effects reduce as individuals age, and others remain remarkably stable from childhood into adulthood. We argue that to advance understanding of developmental mechanisms and direct resources for intervention more effectively, social factors need to be assessed more comprehensively, and genetically sensitive designs should be considered with neuroimaging integrated to test alternative developmental models. As current evidence is based almost exclusively on studies from high-income countries, research from low- and middle-income countries is urgently needed.