Current evolution of neurobehavioral methods

Workplace exposures to neurotoxicants cause a variety of functional impairments, with the profile of deficits depending on the chemical nature, dose and duration of exposure, and individual characteristics that might confer susceptibility. The functional impairments, or neurobehavioral deficits, can include impairments in cognition, mood and mental state, motor or sensory function. Finland's Helena Hänninen was the first to systematize the process of evaluating patients with workplace exposures in the 1960’s, using multiple neuropsychological tests that formed a “battery.” Subsequently, several test systems were developed to assess nervous system deficits in a sensitive and reliable manner. Unlike neurological examinations, which are mainly qualitative (or semi-quantitative) in nature, neurobehavioral tests quantify the magnitude of nervous system deficits. Hence, neurobehavioral assessment is especially useful for detecting sub-clinical nervous system deficits in cross-sectional studies. Neurobehavioral methods are still evolving, with further validation of assessments for different subpopulations (e.g., different languages and cultures, socioeconomic status, and education level). Computerized testing became popular in the 1980s, given their consistency, ease, and economy of administration. Remote computerized testing will allow for the implementation of very large studies at a much lower cost than in-person assessments, but validation of those methods is needed. Neurobehavioral tests must dive deeper (e.g., mapping test results to brain mechanisms) and expand broadly to new frontiers (e.g., routine exams and telemedicine) to fulfill the promise that could only be imagined when the field first discovered the power of those tests to detect subtle, subclinical deficits due to occupational chemical exposures.