No Behavioral or ERP Evidence for a Developmental Lag in Visual Working Memory Capacity or Filtering in Adolescents and Adults with ADHD

Abstract

Attention-deficit/hyperactivity disorder (ADHD) patients have both working memory (WM) and attention problems. Good attention skills are important for WM performance; individuals have higher WM capacity when being able to prevent storage of irrelevant information through efficient filtering. Since it is unknown how filtering ability is associated with WM performance in ADHD, this was investigated in the present study. A visuospatial working memory (VSWM) change detection task with distracting stimuli was administered to adolescents (12–16 years old) and adults (20–46 years old) with and without ADHD matched on education/IQ. Besides performance, contralateral delay activity (CDA) was measured; a neural correlate of the number of targets and distracters encoded and maintained in WM during the retention interval. Performance data showed similar WM-load, WM-distracter interference and developmental effects in ADHD and control groups. Adolescents’ performance on the WM task deteriorated more than that of adults in the presence of distracters and with higher WM-load, irrespective of Diagnosis. The CDA data suggested that initially all groups encoded/maintained distracting information, but only adults were able to bounce this information from memory later in the retention interval, leading to better WM performance. The only effect of Diagnosis was a smaller CDA in adolescents and adults with ADHD than in age/IQ-matched controls when maintaining a low 1-item load, which was possibly related to an inability to keep attention focused at cued stimuli with low task demands. Overall, the development of filtering efficiency and VSWM storage capacity in adolescents with ADHD was not different from that in typically developing peers.

Deficient interference control during working memory updating in adults with ADHD: An event-related potential study

“…Marx et al (2014) found males with ADHD to be more susceptible to (emotional) interference during n-back performance. On the other hand, Spronk et al (2013) found neither behavioral nor ERP evidence of reduced interference control abilities in adolescents and adults with ADHD using a visuospatial working memory change detection task with distracting stimuli.…”

“…The authors concluded that this pattern probably reflects inefficient allocation of processing resources or a limited working memory capacity. Spronk et al (2013), on the other hand, report similar CDA (contralateral delay activity; a negative deflection over the lateral parietal cortex measured in an early window of 450 -550 ms and later window of 550-825 ms after the onset of the memory array) amplitudes in adolescents and adults with ADHD compared to healthy controls during a visuospatial working memory task with high WM load. They argue that the CDA amplitude reflects the number of relevant and irrelevant items that are encoded and maintained in memory.…”

“…However, considering the components of WM (Baddley, 1992), the central executive seems be more impaired than the storage sub-systems in ADHD (Rapport et al, 2008;Kofler et al, 2010). Further, in an ERP study specifically examining WM capacity in adults with ADHD, no abnormalities were found (Spronk et al, 2013). Thus, regarding the population of adults with ADHD, the insensitivity of P300 appears to be more likely associated to deficient allocation of attentional resources during WM.…”

“…However, abnormalities such as increased ERP amplitude variability (Myatchin et al, 2012), reduced ERP amplitudes (Keage et al, 2008;Kim et al, 2014), or atypical WM load effects on ERPs (Gomarus et al, 2009, Spronk et al, 2013 have been consistently found in children, adolescents, and adults with ADHD. Gomarus et al (2009) found the SRN (search-related negativity; a long latency wave 300 -600 ms post-stimulus) in a visual selective memory task to be insensitive to WM load in children with ADHD.…”

Event‐related potential measures of executive functioning from preschool to adolescence

“…The CDA has been used to study working memory in adolescents and adults with ADHD. One study administered a change detection task both to adolescents aged 12 to 16 years, and to adults with and without ADHD and found that performance deteriorated more for the adolescents with ( n =15) and without ( n =19) ADHD than either adult group in the presence of distracters and when there was a higher working memory load . The CDA showed that adults were able to more efficiently remove distracting details from memory later in the retention interval, resulting in better working memory.…”