Assessing the Magnitude of Risk for ADHD in Offspring of Parents with ADHD: A Systematic Literature Review and Meta-Analysis

Intergenerational transmission of genetic risk for hyperactivity and inattention. Direct genetic transmission or genetic nurture?

Background

Hyperactivity and inattention, the symptoms of ADHD, are marked by high levels of heritability and intergenerational transmission. Two distinct pathways of genetic intergenerational transmission are distinguished: direct genetic transmission when parental genetic variants are passed to the child's genome and genetic nurture when the parental genetic background contributes to the child's outcomes through rearing environment. This study assessed genetic contributions to hyperactivity and inattention in childhood through these transmission pathways.

Methods

The sample included 415 families from the Quebec Newborn Twin Study. Twins' hyperactivity and inattention were assessed in early childhood by parents and in primary school by teachers. The polygenic scores for ADHD (ADHD-PGS) and educational attainment (EA-PGS) were computed from twins' and parents' genotypes. A model of intergenerational transmission was developed to estimate (1) the contributions of parents' and children's PGS to the twins' ADHD symptoms and (2) whether these variances were explained by genetic transmission and/or genetic nurture.

Results

ADHD-PGS explained up to 1.6% of the variance of hyperactivity and inattention in early childhood and primary school. EA-PGS predicted ADHD symptoms at both ages, explaining up to 1.6% of the variance in early childhood and up to 5.5% in primary school. Genetic transmission was the only significant transmission pathway of both PGS. The genetic nurture channeled through EA-PGS explained up to 3.2% of the variance of inattention in primary school but this association was non-significant.

Conclusions

Genetic propensities to ADHD and education predicted ADHD symptoms in childhood, especially in primary school. Its intergenerational transmission was driven primarily by genetic variants passed to the child, rather than by environmentally mediated parental genetic effects. The model developed in this study can be leveraged in future research to investigate genetic transmission and genetic nurture while accounting for parental assortative mating.

Anxiety and Disruptive Behavior Symptoms and Disorders in Preschool-Age Offspring of Parents With and Without Bipolar Disorder: Associations With Parental Comorbidity

OBJECTIVE

We examined the relative contribution of parental bipolar disorder (BPD) and psychiatric comorbidities (disruptive behavior disorders [DBD] and anxiety disorders) in predicting psychiatric symptoms and disorders in 2-5-year-old offspring.

METHODS

Participants were 60 families with a parent with BPD and 78 offspring and 70 comparison families in which neither parent had a mood disorder and 91 offspring. Parent and offspring diagnoses and symptoms were assessed using standardized diagnostic interviews and measures, with offspring assessors masked to parental diagnoses.

RESULTS

Offspring of parents with BPD had significant elevations in behavioral, mood and anxiety disorders and symptoms. Both parental BPD and DBD contributed to elevations in child disruptive behavioral symptoms, whereas child anxiety symptoms were more strongly predicted by comorbid parental anxiety. Parental BPD was a stronger predictor than comorbid DBD of child DBDs.

CONCLUSION

Some of the elevated risk for disorders in preschoolers is accounted for by parental comorbidity.

Transdiagnostic risk of mental disorders in offspring of affected parents: a meta-analysis of family high-risk and registry studies

The offspring of parents with mental disorders are at increased risk for developing mental disorders themselves. The risk to offspring may extend transdiagnostically to disorders other than those present in the parents. The literature on this topic is vast but mixed. To inform targeted prevention and genetic counseling, we performed a comprehensive, PRISMA 2020-compliant meta-analysis. We systematically searched the literature published up to September 2022 to retrieve original family high-risk and registry studies reporting on the risk of mental disorders in offspring of parents with any type of mental disorder. We performed random-effects meta-analyses of the relative risk (risk ratio, RR) and absolute risk (lifetime, up to the age at assessment) of mental disorders, defined according to the ICD or DSM. Cumulative incidence by offspring age was determined using meta-analytic Kaplan-Meier curves. We measured heterogeneity with the I2 statistic, and risk of bias with the Quality In Prognosis Studies (QUIPS) tool. Sensitivity analyses addressed the impact of study design (family high-risk vs. registry) and specific vs. transdiagnostic risks. Transdiagnosticity was appraised with the TRANSD criteria. We identified 211 independent studies that reported data on 3,172,115 offspring of parents with psychotic, bipolar, depressive, disruptive, attention-deficit/hyperactivity, anxiety, substance use, eating, obsessive-compulsive, and borderline personality disorders, and 20,428,575 control offspring. The RR and lifetime risk of developing any mental disorder were 3.0 and 55% in offspring of parents with anxiety disorders; 2.6 and 17% in offspring of those with psychosis; 2.1 and 55% in offspring of those with bipolar disorder; 1.9 and 51% in offspring of those with depressive disorders; and 1.5 and 38% in offspring of those with substance use disorders. The offspring's RR and lifetime risk of developing the same mental disorder diagnosed in their parent were 8.4 and 32% for attention-deficit/hyperactivity disorder; 5.8 and 8% for psychosis; 5.1 and 5% for bipolar disorder; 2.8 and 9% for substance use disorders; 2.3 and 14% for depressive disorders; 2.3 and 1% for eating disorders; and 2.2 and 31% for anxiety disorders. There were 37 significant transdiagnostic associations between parental mental disorders and the RR of developing a different mental disorder in the offspring. In offspring of parents with psychosis, bipolar and depressive disorder, the risk of the same disorder onset emerged at 16, 5 and 6 years, and cumulated to 3%, 19% and 24% by age 18; and to 8%, 36% and 46% by age 28. Heterogeneity ranged from 0 to 0.98, and 96% of studies were at high risk of bias. Sensitivity analyses restricted to prospective family high-risk studies confirmed the pattern of findings with similar RR, but with greater absolute risks compared to analyses of all study types. This study demonstrates at a global, meta-analytic level that offspring of affected parents have strongly elevated RR and lifetime risk of developing any mental disorder as well as the same mental disorder diagnosed in the parent. The transdiagnostic risks suggest that offspring of parents with a range of mental disorders should be considered as candidates for targeted primary prevention.

The Heritability of ADHD in Children of ADHD Parents: A Post-hoc Analysis of Longitudinal Data

OBJECTIVE

A growing literature suggests attention-deficit/hyperactivity disorder (ADHD) is a heritable disorder. We evaluated children at risk for ADHD by virtue of having parents with ADHD and compared them with children of parents without ADHD to assess the degree of heritability of ADHD.

METHOD

The sample for this study was derived from three longitudinal studies that tracked families with various disorders, including ADHD. Children were stratified based on presence of parental ADHD, and clinical assessments were taken to evaluate presence of ADHD and related psychiatric and functional outcomes in children.

RESULTS

Children with parental ADHD had significantly more full or subthreshold psychiatric disorders (including ADHD) as well as functional impairments compared to children without parental ADHD.

CONCLUSION

Our findings suggest that offspring of parents with ADHD are at significant risk for ADHD and its associated psychiatric, cognitive, and educational impairments. These findings aid in identifying early manifestations of ADHD in young children at risk.

Is Parents' ADHD Symptomatology Associated With the Clinical Feasibility or Effectiveness of a Psychoeducational Program Targeting Their Children's ADHD?

OBJECTIVE

To examine if the clinical feasibility and effectiveness of a psychoeducational program targeting children's ADHD differ between parents with varying ADHD symptom severities.

METHOD

An open trial analyzed data from 549 parents of children with ADHD aged 3 to 17 years, who participated in psychoeducation at an outpatient habilitation/disability clinic. In all analyses, parents were stratified into three symptom severity groups (low/middle/high) based on scores on an ADHD screening scale.

RESULTS

Parental ADHD symptom severity was not associated with results on any outcome, although the odds of having incomplete data were higher in parents reporting higher symptom severity. Across the entire sample, we observed high program completion rates, positive acceptability ratings and large increases in parental knowledge.

CONCLUSIONS

Psychoeducation may be beneficial regardless of the participating parent's ADHD symptomatology. Further research is needed to examine whether these results are generalizable to parents diagnosed with ADHD, an underrepresented group in our study.