Objective: According to the executive dysfunction theory, symptoms of ADHD are a byproduct of general deficits in executive functioning—particularly inhibition of dominant response. According to the state regulation theory, the symptoms of ADHD are the result of a failure to be aroused by, and subsequently engage with, some tasks. When the task is stimulating or rewarding, a threshold of arousal is crossed and the individual with ADHD is able to engage fully. These two theories predict opposite outcomes on simple vs. complex tasks measuring executive functioning. Executive Dysfunction theory predicts lower performance on difficult cognitive tasks for individuals with ADHD, while State Regulation theory predicts lower performance on simpler tasks. Method: Using a clinical database of adult psychoeducational assessments conducted from 1994-2014 at a major southern university, individuals meeting criteria for ADHD (Not Otherwise Specified, NOS = 53; Inattentive type, I = 105; and hyperactive/Combined type, H/C = 62) and individuals not meeting criteria for any diagnosis (n = 43) were selected. The sample was equally balanced for gender (110 males, 117 females), predominantly Caucasian (86.2%), with an average age of 21.96 years (SD = 7.21). The author then conducted a MANOVA using diagnosis as an independent variable and WAIS-III Digit Span Forward and Backwards raw scores and t-scores on the Halstead-Reitan Trails A and B as dependent variables. Trails A and Digits Forward represented simple cognitive tasks, while Trails B and Digits Backwards required greater mental manipulation and inhibition. Results: There were significant differences between groups for Digits Forward, Digits Backward, and Trails B. For the simpler cognitive tasks, performance declined with diagnostic severity. For the more difficult tasks, the ADHD, NOS group performed better than the No Diagnosis group (See Table 1). Conclusion: The overall pattern of results supports the Executive Dysfunction theory, except for those with ADHD, NOS, for whom the State Regulation Theory is a better match. This may indicate heterogeneity within the attention disorders—especially for individuals endorsing fewer than the six symptoms in one or another category required by the DSM-IV.

Table 1.

Means and Standard Deviations for Each diagnostic group on each test

 Diagnostic Group
 
Measure No Diagnosis n = 43 ADHD, NOS n = 53 ADHD, Inattentive n = 105 ADHD, Hyperactive/Combined n = 62 
Digits Forward (raw score) 11.02 (1.99) 10.87 (2.47) 10.17 (2.33) 9.87 (2.04) 
Trails A t-scores 43.35 (7.55) 43.28 (9.58) 42.40 (11.64) 42.06 (11.87) 
Digits Backward (raw score) 7.14 (2.02) 7.62 (2.83) 6.82 (2.35)) 6.50 (2.01) 
Trails B t-scores 45.93 (10.18) 46.32 (10.07) 44.90 (10.14) 40.86 (11.32) 
 Diagnostic Group
 
Measure No Diagnosis n = 43 ADHD, NOS n = 53 ADHD, Inattentive n = 105 ADHD, Hyperactive/Combined n = 62 
Digits Forward (raw score) 11.02 (1.99) 10.87 (2.47) 10.17 (2.33) 9.87 (2.04) 
Trails A t-scores 43.35 (7.55) 43.28 (9.58) 42.40 (11.64) 42.06 (11.87) 
Digits Backward (raw score) 7.14 (2.02) 7.62 (2.83) 6.82 (2.35)) 6.50 (2.01) 
Trails B t-scores 45.93 (10.18) 46.32 (10.07) 44.90 (10.14) 40.86 (11.32)