Are Motor Inhibition and Cognitive Flexibility Dead Ends in ADHD?

Abstract

Executive dysfunction has been postulated as the core deficit in ADHD, although many deficits in lower order cognitive processes have also been identified. By obtaining an appropriate baseline of lower order cognitive functioning light may be shed on as to whether executive deficits result from problems in lower order and/or higher order cognitive processes. We examined motor inhibition and cognitive flexibility in relation to a baseline measure in 816 children from ADHD and control families. Multiple children in a family were tested in order to examine the familiality of the measures. No evidence was found for deficits in motor inhibition or cognitive flexibility in children with ADHD or their nonaffected siblings: Compared to their baseline speed and accuracy of responding, children with ADHD and their (non)affected siblings were not disproportionally slower or inaccurate when demands for motor inhibition or cognitive flexibility were added to the task. However, children with ADHD and their (non)affected siblings were overall less accurate than controls, which could not be attributed to differences in response speed. This suggests that inaccuracy of responding is characteristic of children having (a familial risk for) ADHD. Motor inhibition and cognitive flexibility as operationalized with mean reaction time were found to be familial. It is concluded that poorer performance on executive tasks in children with ADHD and their (non)affected siblings may result from deficiencies in lower order cognitive processes and not (only) from higher order cognitive processes/executive functions.Keywords Inhibition . Set shifting . Endophenotype . Affected and nonaffected siblings . Familiality Attention-Deficit/Hyperactivity Disorder (ADHD) (American Psychiatric Association [APA] 1994) is associated with impairments in the fronto-striatal-basal ganglia neurocircuitry (Casey et al. 1997;Dickstein et al. 2005;Durston et al. 2003;Giedd et al. 2001). These impairments are hypothesized to be (causally) related to deficits in higher order cognitive processes/executive functions (Barkley 1997;Casey et al. 1997;Fuster 2002;Lovejoy et al. 1999;Mehta et al. 2004;Rubia et al. 1999). Executive deficits in working memory, (motor) inhibition, cognitive flexibility and planning are frequently found in children, adolescents and adults with ADHD (Barkley 1997;Boonstra et al. 2005b;Pennington and Ozonoff 1996;Sergeant et al. 2003;Sergeant et al. 2002;Willcutt et al. 2005). As the term 'higher order cognitive processes' suggests, there are also lower order cognitive processes on which higher order cognitive processes build (Halperin and Schulz 2006;Sergeant 2000;Sergeant et al. 2003;Shallice et al. 1996). Lower order cognitive processes, such as encoding, search, decision and response organization are less complex than higher order cognitive processes (Domin 1999;Parisi 1997;Sergeant 2000) and form necessary components for higher order cognitive operations (Baddeley and Della Sala J Abnorm Child Psychol (2007) 35:957-967

Error monitoring in children with ADHD or reading disorder: An event-related potential study

“…In contrast, we found that children with ADHD made significantly more errors and were more variable in their response speed than children without ADHD. This is a finding that has frequently been reported by others in a diversity of neuropsychological tasks (Rommelse et al, 2007;Sergeant et al, 2003;van der Meere, 2005). The absence of significant group differences in correct versus error RT suggests that the higher error rate in children with ADHD was not due to more impulsive behaviour.…”

“…In addition, it has been claimed that no evidence of a response inhibition deficit can be found when tasks with an experimental manipulation of inhibition load are used and performance is compared to a control condition (Rommelse et al; Van De Voorde, Roeyers, Verté, & Wiersema, in press). The latter has also been found for other executive function (EF) deficits that are frequently attributed to ADHD, such as deficits in working memory (Karatekin, Bingham, & White, 2009;Klein, Wendling, Huettner, Ruder, 4 & Peper, 2006;Shallice et al, 2002;Van De Voorde et al, in press) and cognitive flexibility (Rommelse et al, 2007). With respect to RD, there have been reports of additional deficits that cannot easily be explained by a pure phonological deficit.…”

“…With respect to ADHD, it has been found that children with the disorder show a general inaccurate response style, not only in tasks measuring inhibition, but also in other neuropsychological tasks (Rommelse et al, 2007;Sergeant, Geurts, Huijbregts, Scheres, & Oosterlaan, 2003;van der Meere, 2005). In addition, it has been claimed that no evidence of a response inhibition deficit can be found when tasks with an experimental manipulation of inhibition load are used and performance is compared to a control condition (Rommelse et al; Van De Voorde, Roeyers, Verté, & Wiersema, in press).…”

Circulating phthalates during critical illness in children are associated with long-term attention deficit: a study of a development and a validation cohort

“…Three computerized tasks of the Amsterdam Neuropsychological Tasks (ANT) system were used to quantify attention/alertness, motor coordination, and executive functions [2,3]. Alertness was evaluated by the mean of the reaction time (msec) to 32 visual stimuli and the inconsistency of alertness by the standard deviation of the 32 reaction times.…”

“…Children who have been critically ill at young age suffer from a substantial neurocognitive deficit when assessed years after admission to the pediatric intensive care unit (PICU) [1][2][3][4][5]. This neurocognitive legacy comprises, besides lower scores for intelligence, visual-motor integration, memory and behavior, also an important deficit in executive functions, motor coordination and attention [1].…”