Gestation Age Forecasts ADHD Symptoms for Individuals with Down Syndrome

Laura del Hoyo Soriano

New research suggests gestational age could help predict the later symptoms of attention-deficit/hyperactivity disorder (ADHD) in patients with Down syndrome.

A team, led by Laura del Hoyo Soriano, Department of Psychiatry and Behavioral Sciences, MIND Institute University of California Davis, investigated the influence of gestational age in later symptoms of ADHD.

Patients with Down syndrome frequently suffer from ADHD symptoms as well. However, there is sometimes considerable variation in the expression and severity of the ADHD symptoms.

The study included 105 participants with Down syndrome between 6-18 years old. Each patient was born at or after 35 weeks gestation. The investigators included the maternal age at birth, maternal level of education, household income, sex, chronological age, and cognitive level of each individual in the final analysis.

Patient Population

Each individual in the study was a subset of a large multicenter project—The Down Syndrome Cognition Project (DSCP)—a project of the cognitive and behavioral phenotype of individuals with Down syndrome and the factors influencing phenotypic variability.

Patients were included in the ADHD study if full trisomy 21 had been verified by karyotype, the biological mother was available for participation, and the chronological age of participants with Down syndrome was between 6-18.

The investigators assessed the symptoms of ADHD using the Conners Parent Rating Scale, Third Edition and measured general cognitive level with the Kaufman Brief Intelligence Test, 2nd Edition.

The first part of the study included a descriptive analysis of the sociodemographic and clinical parameters, which were described using central tendency and variability for numeric variables and absolute and relative frequencies for categorical variables.

The investigators found 20 (19%) of the patients had a previous diagnosis of ADHD, 17 (16.2%) of which were taking ADHD medication.

Conclusions

However, there was no association of ADHD outcomes or of gestation age with maternal age at birth, maternal level of education, family income, or sex of participants with Down syndrome.

This was also true for the Global Index of the Conners-3 (P = 0.001; R = -0.32).

Chronological age was not related to the positive (R = -0.08; P = 0.4) or the negative impression scores (R = 0.008; P = 0.9).

On the other hand, chronological age of participants with Down syndrome at the time of the ADHD measurement was linked to T-scores for the Inattentive subscale (R = -0.25; P = 0.01) and the Hyperactive-Impulsive subscale (R = -0.25; P = 0.01).

The results show gestational age is directly related to inattentive and hyperactivity or impulsive symptoms in children and adolescents with Down syndrome, meaning gestational age should be addressed when considering symptoms of ADHD.

The study also may have implications for early interventions, with more attention needed toward the advancement of care and follow-up for infants with down syndrome who are born even late preterm or early term.

“In summary, findings from the current study are promising but need to be considered as preliminary, suggesting that [gestation age] plays a role in the later emergence of ADHD symptoms in children and adolescents with [Down syndrome],” the authors wrote. “Therefore, more attention must be focused on the advancement of care and follow-up for infants with DS who are born even late preterm or early term.”

The investigators said further longitudinal studies including other perinatal, other methods of ADHD assessment, and behavioral measures are needed. The team also wants to include studies examining gestation age < 35 are needed to further explore the impact of fetal immaturity in the future development of patients with Down syndrome.

The study, “Gestational age is related to symptoms of attention-deficit/hyperactivity disorder in late-preterm to full-term children and adolescents with down syndrome,” was published online in Scientific Reports.