Development of intellectual abilities in children with ADHD over the long term – results of the 8.5-year follow-up of the Cologne Adaptive Multimodal Treatment Study (KAMT)

Abstract

In an 8.5-year follow-up of 16- to 22-year-old adolescents and young adults who had received multimodal treatment for attention-deficit/hyperactivity disorder as children, current intellectual performance and the intelligence profile were assessed using the K-TIM and examined while taking into account the effects of age, sex, and type of school attended. Overall performance (standard score 91) as well as fluid and crystallized intelligence scales were in the lower average range, with fluid intelligence more pronounced than crystallized intelligence. Current performance was also compared with performance at the beginning (standard score 96) and end of intensive therapy (standard score 102), assessed using the K-ABC. Longitudinal analyses showed individual correlations in the moderate range. Multiple regression analyses demonstrated that the strongest influence on the Total Intelligence scale (K-TIM) came from the Achievement scale (K-ABC) at the end of treatment, explaining almost 50% of the variance.