Medication adherence in adolescents may improve cognitive test scores, ADHD

Children with ADHD, autism and other comorbid neurodevelopmental diagnoses who had well-controlled ADHD medication use for 1 year had improved cognitive test scores and ADHD symptoms, according to a Journal of Psychiatric Research study.

“Numerous studies have documented efficacy of ADHD medication on core symptoms in the short term, but effects on cognitive development and long-term outcome are less well known,” Mats Johnson, MD, PhD, of University of Gothenburg’s Gillberg Neuropsychiatry Center in Sweden, and colleagues wrote. “The assessment of the role of ADHD medication for long-term outcome is difficult since adherence to the medication is often brief and inconsistent.”

The researchers enrolled 87 participants (61 boys) aged 6 to 18 years (mean age, 11.54 years) diagnosed with ADHD in an ongoing open uncontrolled trial on long-term ADHD medication. Common comorbidities were autism spectrum disorder in 25 adolescents (29%) and subclinical ASD in 21 (24%), with less frequent comorbidities including oppositional defiant disorder (ODD), dyslexia/language disorder, borderline intellectual functioning and developmental coordination disorder.

Johnson and colleagues evaluated symptoms with the ADHD Rating Scale-IV (ADHD-RS) at baseline and 12 months; participants completed Wechsler tests for cognitive assessment at the same time points. The results of these analyses were part of the ongoing 2-year trial on long-term ADHD medication.

Average ADHD-RS score decreased from 34.6 at baseline to 18.34 at 12 months, and 41 participants (47%) attained ADHD symptom normalization at follow-up (ADHD-RS score no greater than 18). Those in the inattentive ADHD subgroup had the most frequent symptom normalization (16/21, 76%), while 25 of 66 participants (38%) in the combined ADHD subgroup had normalized symptoms.

Wechsler scores improved significantly for all participants, which was strongly correlated on an individual basis in all areas except processing speed. The researchers noted this may be due to subscale test variance between Wechsler test versions.

Dyslexia/language impairment was the only significant predictor for improved Wechsler scores; participants with this comorbidity had a larger increase from baseline (M = 11.21, SD = 8.75) than those without it (M = 4.23, SD = 9.72). Those with dyslexia/language impairment also had higher baseline Wechsler scores.

“It is possible that attention deficit is particularly detrimental for cognitive test performance in children with dyslexia/language impairment, who otherwise are known to perform variably on IQ tests,” the researchers wrote.

While the study was limited by its open uncontrolled design,, it was strengthened by its prospective naturalistic design, inclusion of patients with comorbidities and long-term follow-up. Johnson and colleagues suggested more long-term research is needed.

“Future research designed to monitor comprehensive functional and quality of life outcomes in long-term trials could help us learn more about effects of significance in everyday life and give evidence to better inform practitioners and patient families about treatment options,” they wrote.