Early Predictors of ADHD: Evidence from a Prospective Birth Cohort

Early and repeated screening detects children with persistent attention-deficit/hyperactivity disorder

Preschool screening of attention-deficit/hyperactivity disorder (ADHD) has been found too inaccurate to be clinically useful. This may be due to the known instability of ADHD symptoms from preschool onwards, and the use of a single screening only. We hypothesized that by identifying a group of children with persistent ADHD from preschool to school age and repeating the screening, the clinical usefulness of screening would increase. This study is part of the prospective longitudinal, population-based Norwegian Mother, Father and Child Cohort Study, with a diagnostic parent interview at 3.5 years and follow-up with parent questionnaires at ages 5 and 8 years (n = 707). We identified a group classified with ADHD at all three time points (persistent ADHD). We then used the Child Behavior Checklist ADHD DSM-oriented scale at ages 3.5 and 5 years to investigate the accuracies of single- and two-stage screening at different thresholds to identify children with persistent ADHD. About 30% of the children were classified with ADHD at least once across time (at ages 3.5, 5, and/or 8 years), but only 4% (n = 30) had persistent ADHD. At all thresholds, the two-stage screening identified children with persistent ADHD more accurately than single screening, mainly due to a substantial reduction in false positives. Only a small group of children were classified with persistent ADHD from preschool to school age, underlining that future screening studies should distinguish this group from those with fluctuating symptoms when estimating screening accuracies. We recommend a two-stage screening process to reduce false positives.

Attention-deficit/hyperactivity disorder from preschool to school age: change and stability of parent and teacher reports

Identifying attention-deficit/hyperactivity disorder (ADHD) in pre-schoolers may improve their development if treated, but it is unclear whether ADHD symptoms from this age are stable enough to merit treatment. We aimed to investigate the stability of parent- and teacher-reported ADHD symptoms and ADHD classified above the diagnostic symptom thresholds, including for hyperactivity-impulsivity (HI), inattention and combined presentations from age 3 to 8 years. This study is part of the longitudinal, population-based Norwegian Mother, Father and Child Cohort Study. At child age 3 years, parents were interviewed and teachers rated ADHD symptoms. At age 8 years, parents (n = 783) and teachers (n = 335) reported ADHD symptoms by the Child Symptom Inventory-4. We found a significant reduction in the mean number of parent-reported ADHD and HI symptoms from age 3 to 8 years, but otherwise similar mean numbers. Parent-reported ADHD symptoms were moderately correlated between ages, while correlations were low for teachers. A total of 77/108 (71%) of the children classified with parent-reported HI presentation at age 3 years were no longer classified within any ADHD presentation at age 8 years, the only clear trend across time for either informant. There was a low to moderate parent-teacher-agreement in the number of reported symptoms, and very low informant agreement for the classified ADHD presentations. Overall, clinicians should exercise caution in communicating concern about HI symptoms in preschool children. Age 3 years may be too early to apply the ADHD diagnostic symptom criteria, especially if parents and teachers are required to agree.

Genetic nurture versus genetic transmission of risk for ADHD traits in the Norwegian Mother, Father and Child Cohort Study

Identifying mechanisms underlying the intergenerational transmission of risk for attention-deficit/hyperactivity disorder (ADHD) traits can inform interventions and provide insights into the role of parents in shaping their children's outcomes. We investigated whether genetic transmission and genetic nurture (environmentally mediated effects) underlie associations between polygenic scores indexing parental risk and protective factors and their offspring's ADHD traits. This birth cohort study included 19,506 genotyped mother-father-offspring trios from the Norwegian Mother, Father and Child Cohort Study. Polygenic scores were calculated for parental factors previously associated with ADHD, including psychopathology, substance use, neuroticism, educational attainment, and cognitive performance. Mothers reported on their 8-year-old children's ADHD traits (n = 9,454 children) using the Parent/Teacher Rating Scale for Disruptive Behaviour Disorders. We found that associations between ADHD maternal and paternal polygenic scores and child ADHD traits decreased significantly when adjusting for the child polygenic score (pΔβ = 9.95 × 10-17 for maternal and pΔβ = 1.48 × 10-14 for paternal estimates), suggesting genetic transmission of ADHD risk. Similar patterns suggesting genetic transmission of risk were observed for smoking, educational attainment, and cognition. The maternal polygenic score for neuroticism remained associated with children's ADHD ratings even after adjusting for the child polygenic score, indicating genetic nurture. There was no robust evidence of genetic nurture for other parental factors. Our findings indicate that the intergenerational transmission of risk for ADHD traits is largely explained by the transmission of genetic variants from parents to offspring rather than by genetic nurture. Observational associations between parental factors and childhood ADHD outcomes should not be interpreted as evidence for predominantly environmentally mediated effects.

The impact of screen exposure on attention abilities in young children: a systematic review

BACKGROUND

The neurocognitive consequences of exposure to screens in school-aged children have been the subject of multiple studies. However, the relationship between screen exposure and neurocognitive development, especially attentional functions, remains unclear in preschool children. The aim of this systematic review was to evaluate the immediate and long-term impact of screen exposure on attentional functions in preschoolers.

METHODS

Three electronic databases (PubMed, COCHRANE, and SCOPUS) were searched for studies published between January 1, 2000, and November 30, 2020. Two reviewers independently selected studies. Inclusion criteria were observational studies, inclusion of children aged less than seven years with no neurodevelopmental disorders, evaluation of screen time, and evaluation of attentional functions. Data extracted including participants' ages, number of participants, screen exposure time, attention assessment tool, and confounding factors. Study quality was evaluated using the Newcastle-Ottawa Scale.

RESULTS

Five cross-sectional studies were included: all reported significant, positive associations between high levels of screen exposure and attention difficulties. Ten longitudinal studies were included: six found a significant impact of earlier screen exposure on subsequent attentional function and four found no relationship. Eight of the studies included evaluated the direction of the relationship between screen exposure and attentional difficulties: seven suggested the relationship is bidirectional.

CONCLUSIONS

These findings support current guidelines to limit screen time in preschoolers to prevent the development of attention difficulties.

What can a national patient registry tell us about psychiatric disorders and reasons for referral to outpatient services in youth with hearing loss?

BACKGROUND

Studies of reasons for referral to the Child and Adolescent Mental Health Services (CAMHS) and subsequent psychiatric disorders are missing in youth with Hearing loss (HL).

AIMS

To examine the referral reasons to CAMHS and the clinically diagnosed psychiatric disorders in youth with HL among the nationally representative population.

METHODS

The study population was a youth with HL referred to CAMHS and registered in the national Norwegian Patient Registry (NPR) during the years 2011-2016. The results were also compared with some data published from CAMHS for the General Youth Population (GenPop).

RESULTS

Among youth with HL, 18.1% had also been referred to CAMHS compared to about 5% in GenPop, at mean age 9.1 years, >70% before age 13 years vs. 46% in the GenPop. Boys with HL comprised 57% and were referred about two years earlier than girls with HL. Compared to the GenPop, youth with HL were referred more frequently for suspected neurodevelopmental- and disruptive disorders, and less frequently for suspected emotional disorders. Girls with HL were referred for suspected Attention-Deficit/Hyperactivity Disorder (ADHD) at about the same rate as boys with HL in the 7-12 year age group. The most frequently registered psychiatric disorders were ADHD: 29.8%, anxiety disorders: 20.4%, and autism spectrum disorders: 11.0%, while disruptive disorders constituted about 5.0%.

CONCLUSIONS

Youth with HL were referred to CAMHS more often, but earlier than the GenPop, mostly due to ADHD disorders. Although more rarely referred for suspected anxiety disorders, these were frequently diagnosed, suggesting that anxiety was not recognized at referral in youth with HL.

Association of Maternal Use of Triptans During Pregnancy With Risk of Attention-Deficit/Hyperactivity Disorder in Offspring

Importance

Triptans are commonly used in the treatment of migraine. Prenatal exposure to triptans may be associated with adverse fetal neurodevelopment; however, there is limited information about the long-term safety of triptan use during pregnancy.

Objective

To examine the association between maternal use of triptans during pregnancy and diagnosis and symptoms of attention-deficit/hyperactivity disorder (ADHD) among offspring.

Design, Setting, and Participants

This study used data from the Norwegian Mother, Father and Child Cohort Study (recruitment 1999-2008), linked to national health registries. Live-born singleton children born to women with migraine before or during pregnancy were included. Two analytic samples were defined: one to assess ADHD diagnosis and one to assess ADHD symptoms. Data were analyzed from May 1 to November 30, 2021.

Exposure

Maternal self-report of triptan use during pregnancy. Exposed children were compared with 2 groups of unexposed children whose mothers reported migraine (1) during pregnancy and (2) before pregnancy only.

Main Outcomes and Measures

An ADHD diagnosis was defined as diagnosis of hyperkinetic disorder or receipt of dispensed ADHD medication. Symptoms of ADHD at 5 years were measured by the Conners' Parent Rating Scale, where a higher score indicates more symptoms of ADHD. Cox proportional hazards regression models and generalized linear models with inverse probability weights were used to estimate weighted hazard ratios (HRs) and standardized mean differences, respectively, with 95% CIs.

Results

The ADHD diagnosis sample comprised 10 167 children (mean [SD] maternal age, 30.2 [4.6] years; 5231 boys [51.5%]), and the ADHD symptoms sample comprised 4367 children (mean [SD] maternal age, 30.6 [4.4] years; 2191 boys [50.2%]). Children were followed up for a mean (SD) of 10.6 (2.2) years. Children with prenatal triptan exposure had no increased risk of ADHD diagnosis compared with unexposed children whose mothers had migraine during pregnancy (weighted HR, 1.16; 95% CI, 0.78-1.74) and compared with unexposed children whose mothers had migraine only before pregnancy (weighted HR, 1.28; 95% CI, 0.84-1.94). There were no differences in ADHD symptom scores between exposed and unexposed children.

Conclusions and Relevance

The findings of this study suggest that there is no increased risk of ADHD among offspring associated with prenatal exposure to triptans.

Parent-reported Early Atypical Development and Age of Diagnosis for Children with Co-occurring Autism and ADHD

Autism and attention-deficit/hyperactivity disorder (ADHD) often co-occur. This survey of 288 New Zealand parents of children diagnosed with autism (n = 111), ADHD (n = 93), or both conditions (n = 84), examined the relations between age of diagnosis and early atypical development, the age specialist consultation was needed and types of specialists seen. Co-occurring autism and ADHD was associated with an earlier ADHD diagnosis and a later autism diagnosis. Parents of children with both diagnoses reported less atypical development in language and social behaviours compared to parents of children of autism, and this co-occurring group also experienced longer wait times to diagnosis, and saw more types of specialists prior to a diagnosis, than those with autism.

Pregnancy exposure to organophosphate esters and the risk of attention-deficit hyperactivity disorder in the Norwegian mother, father and child cohort study

BACKGROUND

Organophosphate esters (OPEs) are a class of flame retardants in common use. OPEs can easily leach from materials, resulting in human exposure. Increasing concentrations have been reported in human populations over the past decade. Recent studies have linked prenatal OPE exposure to hyperactivity and attention problems in children. Such behaviors are often found among children with attention-deficit hyperactivity disorder (ADHD), however, no study has investigated OPEs in relation to clinically assessed ADHD.

OBJECTIVE

To evaluate prenatal exposure to OPEs as risk factors for clinically assessed ADHD using a case-cohort study nested within the Norwegian Mother, Father, and Child Cohort Study (MoBa).

METHODS

We included in the case group 295 ADHD cases obtained via linkage with the Norwegian Patient Registry, and the sub-cohort group 555 children sampled at baseline, irrespective of their ADHD case status. Prenatal concentrations of OPE metabolites were measured in maternal urine collected at 17 weeks of gestation, and included diphenyl phosphate (DPHP), di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) hydrogen phosphate (BBOEP), and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP). We estimated risk ratios and the corresponding 95% confidence intervals [95% CI] using logistic regression, adjusting for season of urine collection, child sex, birth year, and maternal depression, education, and sum of urinary di(2-ethylhexyl) phthalate metabolites (∑DEHP) concentration during pregnancy. To assess the overall impact of simultaneously decreasing exposure to all chemical constituents of an OPE-phthalate mixture, quantile based g-computation was implemented. The mixture constituents included OPE and phthalate metabolites commonly detected in our study. In all models, we considered effect measure modification by child sex and polymorphisms in genes encoding paraoxonase 1 (PON1) and cytochrome P450 (P450) enzymes. Mediation analysis was conducted using thyroid function biomarkers estimated from maternal blood collected at 17 weeks of gestation.

RESULTS

DPHP was detected in nearly all samples (97.2%), with a higher geometric mean among the case group (0.70 µg/L) as compared to the sub-cohort (0.52 µg/L). DNBP was commonly detected as well (93.8%), while BBOEP (52.9%) and BDCIPP (22.9%) were detected less frequently. A higher risk of ADHD was observed in children with greater than median exposure to DPHP during pregnancy (risk ratio: 1.38 [95% CI: 0.96, 1.99]), which was slightly higher among girls (2.04 [1.03, 4.02]) and children of mothers with PON1 Q192R genotype QR (1.69 [0.89, 3.19]) or PON1 Q192R genotype RR (4.59 [1.38, 15.29]). The relationship between DPHP and ADHD (total risk ratio: 1.34 [0.90, 2.02]) was partially mediated through total triiodothyronine to total thyroxine ratio (natural direct effect: 1.29 [0.87, 1.94]; natural indirect effect: 1.04 [1.00, 1.10]; 12.48% mediated). We also observed an elevated risk of ADHD in relation to BDCIPP detection during pregnancy (1.50 [0.98, 2.28]). We did not observe notable differences in ADHD by DNBP (0.88 [0.62, 1.26]) or BBOEP (1.03 [0.73, 1.46]) during pregnancy. Simultaneously decreasing all constituents of common-detect OPE-phthalate mixture, specifically DPHP, DNBP, and 6 phthalate metabolites, by a quartile resulted in an ADHD risk ratio of 0.68 [0.64, 0.72].

CONCLUSION

Prenatal exposure to DPHP and BDCIPP may increase the risk of ADHD. For DPHP, we observed potential modification by child sex and maternal PON1 Q192R genotype and partial mediation through maternal thyroid hormone imbalance at 17 weeks gestation.

Prenatal exposure to non-steroidal anti-inflammatory drugs and risk of attention-deficit/hyperactivity disorder: A follow-up study in the Norwegian mother, father and child cohort

PURPOSE

To estimate the association between Attention-Deficit/Hyperactivity Disorder (ADHD) in children in preschool and primary school, and prenatal exposure to non-steroidal anti-inflammatory drugs (NSAIDs) by timing and duration.

METHODS

This study was based on the Norwegian Mother, Father and Child Cohort Study linked to the Medical Birth Registry of Norway, the Norwegian Patient Registry (NPR) and the Norwegian Prescription Database (NorPD). NSAID exposure was identified by maternal self-report in pregnancy. Child diagnosis of ADHD was obtained from NPR and NorPD. Symptoms of ADHD at age 5 years were measured using Conners' Parent Rating Scale-Revised, where higher scores correspond to more symptoms. To account for time-varying exposure and confounders, marginal structural models were fitted to estimate hazard ratios and mean difference in z-scores.

RESULTS

The analyses on ADHD diagnosis and ADHD symptoms included 56 340 and 34 961 children respectively. Children exposed to NSAIDs prenatally had no increased risk of ADHD diagnosis (first trimester: HR 1.12, 95% CI 0.86;1.45, second trimester: HR 0.98, 95% CI 0.69;1.38, third trimester: HR 0.68, 95% CI 0.31; 1.46) or ADHD symptoms (first trimester: standardized mean difference 0.03, 95% CI -0.03;0.09, second trimester: standardized mean difference 0.03, 95% CI -0.04;0.11, third trimester: standardized mean difference 0.11, 95% CI -0.03; 0.25). There was no duration-response relationship for either outcome.

CONCLUSION

Though non-differential misclassification of the exposure may have attenuated results, these findings are reassuring and suggest no substantially increased risk of ADHD diagnosis or symptoms in children prenatally exposed to NSAIDs, regardless of timing or duration.

Child and Parental Characteristics of Medication Use for Attention-Deficit/Hyperactivity Disorder

Objectives: To investigate child and parental characteristics of medication use for attention-deficit/hyperactivity disorder (ADHD). Methods: Participants were part of the prospective population-based Norwegian Mother, Father and Child Cohort study (MoBa) (n = 114,500 children, 95,000 mothers, and 75,000 fathers). This cohort was linked to the Norwegian Prescription Database (NorPD) and the Norwegian Patient Registry (NPR) to compare child and parental characteristics in children medicated and not medicated for ADHD during years 2008-2013. Results: One thousand seven hundred and sixty-four children (74% boys) with ADHD (International Classification of Diseases [ICD-10]: F90 and F98.8) were identified. One thousand three hundred and sixty-two (77%) used medication. Boys and girls did not differ in the use of ADHD medication (both 77%). Mean age at first prescription was 9 years in both boys and girls, and age at ADHD diagnosis was 8 years in medicated and unmedicated children. Significantly more hyperkinetic conduct disorders (F90.1), and significantly fewer with attention-deficit disorder (F98.8) were found among the medicated children compared to the unmedicated children. The medicated children also had a significantly lower global functioning (Child Global Assessment Scale). Child disruptive symptoms reported in the MoBa child age 3 year questionnaire were significantly higher in children who used medication compared to the nonusers (t = 2.2, p = 0.03), and group differences in ADHD symptoms at age 3 years were close to significant (t = 1.8, p = 0.07). Other preschool child and parental characteristics were not significantly different in the two groups. Conclusion: In this large birth cohort study, where a great majority of children with ADHD used medication, only child characteristics were significantly associated with the use of medication. We could not replicate previous findings suggesting that "environmental factors," such as parental education and psychopathology, drive medication use. The small differences between medicated and unmedicated children in this cohort study, where a majority used medication, might be due to strong established clinical practices where medication is offered as a treatment option, particularly for hyperkinetic conduct disorder in an egalitarian high-income society.

Increased prevalence of parent ratings of ADHD symptoms among children with bilateral congenital cataracts

AIM

To investigate the behavioral and psychological disorders and the prevalence of parent ratings of attention deficit hyperactivity disorder (ADHD) symptoms among children with bilateral congenital cataracts (CCs).

METHODS

This cross-sectional study investigated children with bilateral CC aged 3-8y (CC group) using Conners' Parent Rating Scale-48 (CPRS-48) from July to December 2016. The abnormal rates of psychological symptoms in CC children and normal vision (NV) children were compared using the Chi-square test. The scores of CC children were compared with those of NV children and the Chinese urban norm using the independent samples t-test and one-sample t-test, respectively.

RESULTS

A total of 262 valid questionnaires were collected. The ratio of CC children to NV children was 119:143. The overall rate of psychological symptoms in CC children was 2.28 times higher than that in NV children (46.22% vs 20.28%, Pearson's χ ²=20.062; P<0.001). CC children showed higher scores for conduct problems, learning problems, impulsiveness/hyperactivity, anxiety, and hyperactivity index than NV children and the Chinese urban norm, particularly between the ages of 3 and 5y. Furthermore, male children aged between 6 and 8y showed a higher impulsive/hyperactive score than females of the same age (t=6.083, P<0.001).

CONCLUSION

Children with bilateral CCs have a higher rate of ADHD symptoms than children with NV. This study provides clinical evidence that screening for psychological symptoms and particularly for ADHD symptoms in children with bilateral CC are recommended for an early diagnosis and timely treatment.

Impact of prenatal exposure to benzodiazepines and z-hypnotics on behavioral problems at 5 years of age: A study from the Norwegian Mother and Child Cohort Study

Many women experience anxiety or sleep disorders during pregnancy and require pharmacological treatment with benzodiazepines (BZDs) or z-hypnotics. Limited information is currently available on how prenatal exposure to these medications affects behavioral problems in children over the long term. Therefore, from a public health perspective, this issue is highly important. The present study aimed to determine whether prenatal exposure to BZDs and z-hypnotics affected externalizing and internalizing behavior problems in children at age 5 years. This study was based on The Norwegian Mother and Child Cohort Study and The Medical Birth Registry of Norway. The final study population included data for 36 401 children, from questionnaires completed by the mothers throughout the 5-year follow up. Children’s behaviors were measured at age 5, based on parental responses to The Child Behavior Checklist. Children T-scores of 63 or above were considered to indicate clinically relevant behavior problems. We applied inverse probability of treatment weighting (IPTW) and log-binomial regression models to estimate risk ratios (RRs) and bootstrapped 95% confidence intervals (CIs) with censoring weights to account for loss during follow-up. Several sensitivity analyses were performed to assess the robustness of the main results. The final sample included 273 (0.75%) children that were exposed to BZDs and/or z-hypnotics during pregnancy. The main, IPTW and censoring weighted analyses showed that prenatal exposure to BZD and/or z-hypnotics increased the risks of internalizing behavioral problems (RR: 1.35, 95% CI: 0.73–2.49) and externalizing behavioral problems (RR: 1.51, 95% CI: 0.86–2.64). However, based on sensitivity analyses, we concluded that the risks of displaying externalizing and internalizing problems at 5 years of age did not significantly increase after prenatal exposure to BZDs and/or z-hypnotics. Instead, the sensitivity analyses suggested that residual confounding and selection bias might explain the increased risks observed in the main analyses.

The predictive validity of the Strengths and Difficulties Questionnaire for child attention-deficit/hyperactivity disorder

We need accurate screening measures for attention-deficit/hyperactivity disorder (ADHD) to ensure that children with the disorder are referred for assessment without raising concern for children with normal behaviour. The Strengths and Difficulties Questionnaire (SDQ) provides hyperactivity-inattention (HI), conduct, emotional and peer problem subscales and impact scores that may be used for screening. The aim of the study was to investigate the predictive validity of the Danish version of the parent SDQ HI subscale at the child age of 7 years for subsequent clinically diagnosed ADHD (age 8-15 years). Participants were part of the Danish National Birth Cohort (N = 51,096), and children with ADHD were identified through the Danish National Health registries (n = 943). Receiver operating characteristic analysis showed that the screening accuracy for the HI scores was good (area under the curve = .84). With Cox multivariate regression analysis, we found that SDQ HI subscale scores ≥ 7 with impact gave a nearly 14-fold [hazard ratio (HR) = 13.59] increased risk for ADHD, while conduct and emotional problems indicated low risk (HRs of 1.62 and 1.67, respectively). For the HI subscale to be a sensitive measure for ADHD, a low cutoff (4) was needed, but gave many false screening positives (PPV = .02). Although the diagnostic accuracy of the parent version of the SDQ HI subscale for predicting ADHD was good, our results question the feasibility of screening the general child population for ADHD with only the parent SDQ HI subscale.

Prenatal exposure to dental amalgam and risk of symptoms of attention-deficit and hyperactivity disorder (ADHD)

BACKGROUND

ADHD is multifactorial, including both genetic and environmental factors. The safety of amalgam used in dental treatment has been discussed due to its content of mercury and potential risks for negative neurodevelopmental consequences in the offspring. The aim of the study was to investigate possible associations between symptoms related to ADHD in children of three and five years of age and prenatal exposure to mercury from mothers' amalgam fillings.

METHODS

Data from the Norwegian Mother and Child Cohort Study (MoBa) were used. Data were collected by questionnaires sent to participating women in week 17 (Q1) and 30 (Q3) of pregnancy and when the child was three (Q6) and five years of age (Q7). Information about exposure to amalgam during pregnancy was obtained from Q3. Information about symptoms related to ADHD was obtained from Q6 and Q7. Valid data were obtained for 42 163 children at three years of age and 23 392 children at five years of age. Logistic regression models, including mothers' age, education, body mass index, parity, smoking and alcohol consumption during pregnancy, were used to estimate the association between ADHD symptoms and prenatal exposure to amalgam fillings.

RESULTS

No significant associations between number of teeth with amalgam filling, amalgam fillings placed or removed during pregnancy, and symptoms related to ADHD in children of three and five years of age were found.

CONCLUSIONS

In a large, prospective cohort study, we found no indication of increased risk of ADHD-related symptoms in children prenatally exposed to mother's amalgam fillings.