The efficacy of current psychodiagnostic instruments in distinguishing between ADHD and Non-ADHD in an adult population

D.Litt. et Phil. (Psychology)Abstract: Background: One of the diagnostic controversies in adult attention-deficit/hyperactivity disorder (aADHD) relates to assessment. This study investigates the usefulness of the Wechsler Adult Intelligence Scale-III (WAIS-III), the Cambridge Neuropsychological Test Automated Battery (CANTAB), and the Millon Clinical Multiaxial Inventory-III (MCMI-III) in being able to distinguish between ADHD and non-ADHD (nADHD) in an adult sample. Methods: Ninety four participants (aADHD=51; nADHD=43) aged 19–48 years completed selected psychodiagnostic instruments. Mann-Whitney U, chi-square, and Fisher exact tests were used to determine significant differences between the aADHD and nADHD groups. Effect sizes and statistical power were reported for all the psychodiagnostic instruments. Results: Significant differences between the two groups were found on certain WAIS-III subtests, discrepancy scores, and indices. On the CANTAB, significant differences were found on 2 subtests. Findings on the MCMI-III indicated significant differences between the aADHD and nADHD on only 4 of the clinical personality patterns. Statistical analysis thus indicated the aADHD group could only be distinguished when many psychodiagnostic instruments were used in a combined assessment. An aADHD psychodiagnostic profile is presented based on the findings of the neuropsychological and personality profiles. Conclusions: None of these psychodiagnostic instruments can alone adequately differentiate between aADHD and nADHD in an adult sample. Psychodiagnostic assessment can, however, provide an adequate understanding of the core deficits associated with aADHD. The resultant clinical picture based on neuropsychological and personality contributes to resolving controversy around aADHD assessment practice. The clinical presentation offers guidelines for psychodiagnostic assessment and for making accurate diagnosis of ADHD in adults