Basic processes as foundations of cognitive impairment in adult ADHD

Abstract

Attention deficit hyperactivity disorder (ADHD) in adulthood is associated with impairment of multiple aspects of cognition which adversely affect the individual’s everyday functioning. However, little is known about how these impairments are intertwined. This study explores whether impairments in basic processes (processing speed and distractibility) in adults with ADHD explain impairments in higher order functions, namely executive functions, memory, and complex attention. Furthermore, it is explored whether pharmacological treatment with methylphenidate (MPH) affects basic processes and higher order functions. A between-subjects design compared patients with ADHD without stimulant drug treatment (N = 55) and patients with ADHD treated with MPH (N = 31) with a healthy control group (N = 80). A neuropsychological test battery assessing basic processes and higher order functions was administered. Hierarchical logistic regression analyses were performed to evaluate the contribution of basic processes to impairments in higher order functions. Patients with ADHD not treated with MPH showed impairments in basic processes and higher order functions compared to controls. The impairments in basic processes explained 41–43% of impairments in executive functions, 27–29% in memory, and 56–74% in complex attention. In patients with ADHD treated with MPH, basic processes were not impaired and did not contribute significantly to impairments of higher order functions. Basic processes may constitute part of the foundation of cognitive impairments in adult ADHD. MPH may improve cognitive performance, presumably through improving basic processes. Applying this information could optimize neuropsychological assessments and inform treatment strategies by targeting basic processes.

Neuropsychological functioning of individuals at clinical evaluation of adult ADHD

“…Further research is therefore needed on the extent to which neuropsychological tests can effectively be used to guide psychological interventions. Finally, findings of earlier research (Butzbach et al 2019; Holst and Thorell 2017) could be confirmed by demonstrating significant correlations between basic cognitive functions and higher-order cognitive functions in the ADHD group. The observed associations support the impairments in basic functions may lead to impairments in higher-order functions, such as aspects of complex attention and executive control.…”

“…However, we expect that effect sizes of impairments between groups differ across functions and will not exceed small to medium size (Boonstra et al 2005;Hervey et al 2004;Marchetta et al 2008;Mostert et al 2015;Pettersson et al 2018). Moreover, as motivated by previous findings (Butzbach et al 2019;Holst and Thorell 2017;Boonstra et al 2010), we aim to quantify the effect of basic cognitive functions (i.e., processing speed and distractibility) on more complex cognitive functions (i.e., different aspects of complex attention and executive control) in adults with ADHD and seek to determine whether this hierarchical relationship is shaped differently in groups not having ADHD, such as being diagnosed with other psychiatric disorders or did not fulfill the diagnostic criteria of any psychiatric disorders.…”

“…The findings of a hierarchical relationship between basic and higher-order cognitive functions may not only be utilized to optimize neuropsychological assessment, but provides also implications for the treatment of cognitive deficits of patients with psychiatric conditions. Previous research already demonstrated that stimulant drug treatment improves basic cognitive functions, i.e., processing speed and reaction time variability, which in turn may indirectly improve higher-order cognitive functions (Bron et al 2014;Butzbach et al 2019;Kofler et al 2013;Wong and Stevens 2012). Similarly, cognitive remediation programs aiming to improve processing speed and other aspects of basic attention may have a broader area of effect than initially assumed, and may also impact on higher-order functions (Sonuga- Barke et al 2014).…”

Adult attention-deficit/hyperactivity disorder symptoms, cognitive dysfunction and quality of life in high-dose use of benzodiazepine and Z-drug

“…Another limitation is that adult ADHD was not subtyped (i.e., predominantly inattentive, predominantly hyperactive-impulsive, combined), but cognitive dysfunctions were not reported to be consistently different across these subtypes (Tucha et al 2008;LeRoy et al 2019). Moreover, our comprehensive battery of objective neuropsychological tests (Tucha et al 2015) included the main domains, but did not assess some ADHD−related behavioral features (e.g., reward responsivity, emotional dysregulation, and temporal discounting) and basic processes that have been hypothesized to contribute to higher order cognitive dysfunction in adult ADHD (Butzbach et al 2019). Future studies should include a larger number of neuropsychological measures (Fuermaier et al 2019).…”

Metacognition, psychopathology and daily functioning in adult ADHD

“…This indicates that the more inattentive symptoms are present, the lower metacognitive abilities may be, which could point toward the relevance of bottom-up processing for attention and metacognition. Basic processes may constitute part of the foundation of cognitive deficits in adult ADHD (Butzbach et al, 2019;Guo et al, 2020). One may suggest that impairments in attention may result in impairments in higher order functions building up on them (metacognition) in adults with ADHD.…”