Are cognitive deficits in attention deficit/hyperactivity disorder related to the course of the disorder? A prospective controlled follow-up study of grown up boys with persistent and remitting course

Abstract

To investigate the longitudinal course of cognitive functions in boys with persistent and remittent ADHD from childhood into young adult years. Males (n=217) 15-31 years with and without ADHD were assessed at 3 time points over 10 years into young adulthood. Subjects were stratified into Remittent ADHD, and Persistent ADHD based on the course of ADHD. Cognitive domains included: 1) overall IQ (overall IQ, block design IQ, vocabulary IQ, 2) achievement scores in reading and math and measures of executive function (Wechsler arithmetic, digit span, digit symbol, Rey-Osterrieth, Wisconsin Card Sorting Test, and the Stroop Test). Cognitive outcomes were modeled as a function of group (Controls, Remittent ADHD, and Persistent ADHD), age, group by age interaction, and any demographic confounders using linear growth-curve models. There were no significant interaction effects of group by time. Main group effects indicated that persistent and remittent ADHD groups both had significantly lower scores on all cognitve outcomes compared to Controls and these did not differ between them. Psychometrically-defined cognitive deficits are relatively stable into young adult years and appear to be independent of the course of ADHD. More work is needed to help define the implications of these deficits in individuals with a remitting course of ADHD.

Will Working Memory Training Generalize to Improve Off-Task Behavior in Children with Attention-Deficit/Hyperactivity Disorder?

“…Neuropsychological testing reveals moderate-to-marked impairment in WM in children with ADHD, both in initiating WM and in the limits of storage, particularly in the visuospatial domain [16][17][18][19][20][21][22][23][24]. These WM deficits may contribute significantly to inefficient learning, behavioral problems, executive dysfunction, and the eventual underachievement that children with ADHD often experience [25][26][27][28][29].…”

Neurobiology of Attention Deficit/Hyperactivity Disorder

“…Compared with controls, subjects with ADHD show deficits in executive functions, especially in tasks involving executive control (response inhibition, working memory) (23), have variable response speed (24), show delay aversion (25), and variability in motor timing (26). Cognitive deficits in ADHD have shown to persist over time, even in subjects showing remission of behavioral symptoms (27). Unaffected co-twins of ADHD performed worse than controls in a majority of neuropsychological tasks.…”

Heterogeneity in Clinical Symptoms and Cognitive Functioning of Children with Hyperactivity-Impulsivity and Inattention: Dimensional and Person-Centered Perspectives

“…Moreover, deficits in other various spheres of cognitive functioning were observed in children with ADHD symptoms: they achieve lower results on standardized tests of general intelligence (lower by 9 points, equivalent to 0.6 standard deviations) and reading and math tasks (Biederman et al, 2009;Ek et al, 2007;Frazier, Demaree & Youngstrom, 2004) and these abilities vary depending on ADHD subtype (Marshal, Hynd, Handwerk, & Hall, 1997). Therefore, executive function weakness is not a single, core dysfunction that leads to ADHD symptoms.…”

“…These researchers emphasized the importance of including IQ scores in models explaining the emergence of symptoms in neurodevelopment disorders. This postulate seems particularly important in children with inattention and hyperactivity-impulsivity symptoms as cognitive deficits are part of the clinical picture of ADHD (Biederman et al, 2009;Ek et al, 2007;Frazier et al, 2004). As indicators of IQ we chosen two subtests from the Wechsler Intelligence Scale for Children: Block Design that measures visuospatial functioning and Vocabulary test that measures verbal functioning.…”