A Comparison of Sustained Attention Between Adults With and Without ADHD: Is ADHD the Result of Excessive Habituation?

Abstract

The current study used electroencephalography (EEG) to elucidate the nature of habituation in Attention-Deficit/Hyperactivity Disorder (ADHD). Habituation describes the reduction of response to a stimulus over time. The following paper reviews the function of dopamine in attentional processes related to information saliency and sensory gating in the context of ADHD. ADHD symptomatology and the use of stimulant medications for ADHD treatment is discussed. The neuroanatomy of dopamine in the basal ganglia and prefrontal cortex, three major dopamine pathways, and two families of dopamine receptor types are explained. The attentional networks of alerting, orienting, and executive functioning measured by the Attention Network Task (ANT; Fan et al., 2002) are discussed in the context of ADHD. Previous research exploring dopaminerelated attentional processing is reviewed. Finally, the use of EEG to explore habituation in terms of event-related potential is justified. The current study aimed to use EEG to offer evidence that ADHD is the result of excessive habituation. Adult participants (N = 68) aged 18 - 48 (M = 21, SD = 5) with and without ADHD were recruited to participate in an in-person EEG experiment. Participants with ADHD attended sessions both on and off their stimulant medication. EEG was used to measure the habituation of neural response to a repeating identical tone stimulus. ANT scores were used to provide a behavioral measure of ADHD deficits to compare with habituation. Expected covariates of habituation (e.g., chronic anxiety, ADHD symptom severity) were explored. Additionally, all participants were tested for ADHD symptoms using the Adult Self Report Scale (ASRS; Kessler et al., 2005). Results indicated that stimulant medication boosted neural response to the repeating tone. However, individuals with ADHD did not significantly differ from healthy controls in terms of magnitude of response to the tone nor habituation to the tone over time.