Working Memory Training in Attention-Deficit/Hyperactivity Disorder: Neural Mechanisms of Change

Brief Summary

Detailed Description

Attention-Deficit/Hyperactivity Disorder (ADHD) and Learning Disability (LD) are among the most common neurobehavioural disorders, with prevalence rates estimated at about 5% to 9% . Approximately 4% of youth in the United States have a comorbid diagnosis of ADHD and a Learning Disability (ADHD/LD). Research has shown ADHD/LD symptoms persist into young adulthood, a time when many are enrolled in post-secondary education. Students with ADHD/LD at the post-secondary education level constitute an emergent subgroup of the ADHD and LD populations that have received far less attention in the literature compared to children, adolescents and employed adults. The actual percentage of college students with ADHD/LD is unknown; however, some estimates suggest that 2-8% of students attending post secondary education have ADHD, LD or both. Youth with the additive problems of both disorders are at high risk for academic failure, and poor psychosocial and occupational outcomes in adulthood. The "multiple deficit model" suggests that there is a common genetic and neuropsychological underpinning to these disorders. For example, ADHD and LD share similar features, such as core deficits in processing speed and working memory. ADHD and LD are each associated with several cognitive difficulties including poor working memory (WM) and processing speed. WM is a "mental workspace" that provides temporary storage and manipulation of information and is closely related to g, a proposed measure of general cognitive ability. In addition, WM has also been found to predict academic achievement. One major problem is that current intervention approaches for ADHD/LD do not target the underlying cognitive deficits fundamental to these diagnoses. Thus, interventions that address underlying cognitive difficulties, such as WM, are a promising avenue of additional treatment for youth with combined ADHD/LD. WM capacity has generally been thought to be a fixed trait, but recent studies have suggested that it can be improved by intensive and adaptive computerized training. This intervention approach has been evaluated in children and adolescents with ADHD, older adults, and adult stroke patients and shown promising results. Subjects not only improved on the trained WM tasks, but some of the studies suggest that improvements may generalize to non-trained WM activities, complex reasoning tasks, academic functioning, and behavioral symptoms of ADHD or working memory failure. Moreover, brain imaging studies have provided converging evidence of training-related improvements in working memory: specifically increased activation has been found in cortical regions implicated in working memory. However, no studies to date have investigated whether WM capacity can be improved in a population of young adults with ADHD/LD enrolled in post-secondary education programs. Nor have the results been replicated or elaborated upon using different imaging methodologies, like EEG (Electroencephalography), which is able to capture the millisecond time parameters of cognitive processing and so may provide new insights into the neural mechanism of WM and effects of WM training. The overall objective of the current study is to determine the effectiveness of WM training, as administered by community-based psychologists licensed to provide this training, for college students with ADHD/LD. Specific objectives are to determine whether; i) standard-length computerized WM training enhances WM capacity in college students with ADHD/LD, using behavioral as well as neuro-imaging indices of change; ii) shortened-length WM training would also result in improvements in WM; iii) WM training normalizes WM performance, as compared to typically developing peers (i.e., a healthy comparison group of college students); iv) improvements in WM will generalize to secondary outcome tasks, such as inhibitory control and planning; v) WM training will also ameliorate ADHD symptoms of inattention and hyperactivity; and vi) improvements will be sustained for at least a few months after completing the training.

Primary Outcomes

Secondary Outcomes

• Adult ADHD Self-Report Scale (ASRS v1.1)(within 120 days)
• 'Add-3' working memory test(within 120 days)
• Cambridge Neuropsychological Testing Automated Battery: Spatial Span Task(within 120 days)
• Wide Range Assessment of Memory and Learning: Finger-Windows subtest(within 120 days)
• Barkley Deficits in Executive Functioning Scale (BDEFS)(within 120 days)
• Cognitive Failures Questionnaire(within 120 days)
• Go-nogo task (N200, P300)(within 120 days)
• Delayed Working Memory Task (P300)(within 120 days)
• Selective Working Memory Task (CDA)(within 120 days)