Master of Arts, The Ohio State University, 2019, Psychology
Attention-deficit and hyperactivity disorder (ADHD) is one of the most frequently diagnosed disorders. Nevertheless, phenotypes of ADHD are heterogenous, and remain vaguely defined. For instance, current cognitive test procedures are often inconclusive on the characteristics of ADHD and frequent comorbidities are mostly neglected.
This thesis is composed of three parts: The first part describes existing approaches (e.g., theories, ADHD subtypes, comorbidities), as well as empirical findings from current test procedures (e.g., neurocognitive tasks) for ADHD across eight cognitive domains. It will be shown that the findings from these reviews point towards a spectrum of ADHD and comorbidities that often seem beyond the scope of existing studies, because of the nature of the administered test procedure, the type of applied analysis, as well as the pre-categorization of participants.
The third part therefore introduces a proposal for measuring a spectrum of not only ADHD, but also comorbidities in a set of test procedures susceptible to identified clinical characteristics.
To support these proposals, the second part describes the results from the application of the Ratcliff Diffusion Model to the neurocognitive test performances of an existent clinical dataset (e.g., the MTA study). It will be illustrated that significant differences between controls and ADHD children become apparent, when accounting for gender and medical treatment. Specifically, unmedicated ADHD children seem to take less time for cue retrieval and motor output (smaller Ter), accumulate information at a slower rate (smaller v), and show higher variability in response times. ADHD boys are characterized by a small Ter when interstimulus interval is short, whereas ADHD girls are characterized by an overly conservative decision criterion (large a). Moreover, stimulants not only increase drift rates as suggested by previous studies, but also reduce the gender-specific ADHD characteristics (e.g., small (open full item for complete abstract)
Committee: Roger Ratcliff Prof. Dr. (Advisor); Patricia Van Zandt Prof. Dr. (Committee Member); Eugene Arnold Prof. MD. M.Ed. (Committee Member)
Subjects: Clinical Psychology; Cognitive Psychology; Neurobiology; Neurosciences; Psychobiology; Psychological Tests; Psychology; Quantitative Psychology