Patients with urea cycle disorder struggle when driving: A functional near-infrared spectroscopy review

Previous studies have shown that lack of attention and delayed reactions cause most car crashes. Populations with known deficits in executive function domains such as inattention and lack of mobility would potentially be vulnerable. Understanding the underlying neural networks that are responsible for driving behavior is important to train safe drivers. In rare diseases, particularly inborn errors of metabolism such as urea cycle disorders (UCD), we are starting to unravel the underlying neural networks that are impacted by exposure to toxic metabolites. Patients with inborn errors of metabolism are living into adulthood due to better treatments. Driving is considered an intricate adult task that requires higher-level executive function. Higher-level executive functioning involves the ability to manage complex tasks requiring focus on the task such as attention to the road, while simultaneously, managing relevant information and distractions, and adapting to the task demands. During a recent adult focus group of patients with UCD, we learned that at least 50% of them decided to never drive or stop driving. UCD is associated with executive dysfunction, which may affect their driving. Functional near-infrared spectroscopy (fNIRS) is one of the most effective modalities to examine neural activation related to executive function, working memory, attention, and cognitive development. We have previously shown hemodynamic variations for UCD patients compared to controls in a twin case study. Here, we are reviewing the use of imaging modalities such as fNIRS to detect brain biomarkers in adult individuals with neurological dysfunction such as UCD during a driving task.