Memory-guided force output is associated with self-reported ADHD symptoms in young adults

Abstract

Attention-Deficit/Hyperactivity disorder (ADHD) is the most commonly diagnosed mental health disorder in childhood and persists into adulthood in up to 65% of cases. ADHD is associated with adverse outcomes such as the ability to gain and maintain employment (Kessler et al. 2009; Kupper et al. 2012), and is associated with an increased risk for substance abuse (Groenman et al. 2013; Upadhyaya 2008; Wilens et al. 1995), obesity (Albayrak et al. 2013; Cortese et al. 2008; Nazar et al. 2012; Nazar et al. 2014), workplace injuries (Breslin and Pole 2009; Hodgkins et al. 2011; Swensen et al. 2004), and traffic accidents (Barkley and Cox 2007; Barkley et al. 1993; Jerome et al. 2006a; Jerome et al. 2006b; Merkel et al. 2013). A majority of diagnosed children have motor deficits, however few studies have examined motor deficits in young adults. This study provides a novel examination of visuomotor control of grip force in young adults with and without ADHD. Participants were instructed to maintain force production over a 20-second trial with and without real-time visual feedback about their performance. The results demonstrated that when visual feedback was available, adults with ADHD produced slightly higher grip force than controls. However, when visual feedback was removed, adults with ADHD had a faster rate of decay of force, which was associated with ADHD symptom severity and trait impulsivity. These findings suggest that there may be important differences in the way that adults with ADHD integrate visual feedback during continuous motor tasks. These may account for some of the motor impairments reported in children with ADHD. These deficits could result from (1) dysfunctional sensory motor integration and/or (2) deficits in short-term visuomotor memory.

Deficits in inhibitory force control in young adults with ADHD

“…More broadly speaking, adults with ADHD have impaired visuomotor memory in gripping tasks (Neely et al, 2016), visuomotor adaptation in reaching tasks (Kurdziel et al, 2015), deficits in oculomotor control (Feifel et al, 2004; Carr et al, 2006), increased postural sway (Hove et al, 2015), and impaired timing finger tapping tasks (Valera et al, 2010). The force task employed here provides a precise and continuous measure of motor output, which in future studies could be correlated with behavioral or neuroimaging data to help pinpoint the neurological cause of the impairment.…”

“…Though less often discussed, motor impairments are prominent among children with ADHD (Barkley, 1998) and up to 50% of pediatric ADHD patients are also comorbid for developmental coordination disorder (Kadesjo and Gillberg, 1999; Pitcher et al, 2003; Gillberg et al, 2004). Similarly, adults with ADHD have impaired visuomotor memory in gripping tasks (Neely et al, 2016), visuomotor adaptation in reaching tasks (Kurdziel et al, 2015), deficits in oculomotor control (Feifel et al, 2004; Carr et al, 2006), increased postural sway (Hove et al, 2015), and impaired timing in finger tapping tasks (Valera et al, 2010). These findings are important because motor processes have clearer neural correlates than many of the cognitive constructs associated with ADHD.…”

Memory-guided force control in healthy younger and older adults

“…Thus, in the absence of visual feedback, participants initially rely on proprioceptive (Johansson and Cole 1992) and somatosensory (Johansson and Cole 1992; Johansson and Westling 1984; Marsden et al 1983) feedback and then subsequently rely on stored internal representations to make adjustments (Vaillancourt and Russell 2002). In two recent investigations, our group evaluated memory-guided grip force control in individuals with Attention-Deficit/Hyperactivity Disorder (ADHD; Neely et al 2016a) and Autism Spectrum Disorder (ASD; Neely et al 2016b). We reported a steeper rate of force decay for both ADHD and ASD compared to age- and sex- matched controls.…”

“…We reported a steeper rate of force decay for both ADHD and ASD compared to age- and sex- matched controls. Further, the rate of force decay was associated with more severe social-communication abnormalities and reduced cognitive abilities in individuals with ASD (Neely et al 2016b) and with ADHD-related symptoms and trait impulsivity in young adults with and without ADHD (Neely et al 2016a). As a result, we suggested that the decay of force output in the absence of visual feedback could be related to deficits in short-term or visuospatial working memory; however, we did not explicitly measure memory in either study.…”

“…As a result, we suggested that the decay of force output in the absence of visual feedback could be related to deficits in short-term or visuospatial working memory; however, we did not explicitly measure memory in either study. Although motor memory has been examined in studies of continous force production without visual feedback (Neely et al 2016a; Neely et al 2016b; Poon et al 2012; Vaillancourt and Russell 2002; Vaillancourt et al 2001), no extant studies have investigated the relationship between memory-guided force and specific neuropsychological measures of short-term or working memory. The present investigation sought to address this gap by studying the association of age-related differences in working and short-term memory and memory-guided force control.…”