Neurobehavioral Testing

Overview


Neurobehavioral testing is a non-invasive method used to evaluate the performance of the central nervous system in an individual or group with similar exposures. Test batteries consist of tasks that measure performance of particular neurologic function, such as ability to learn, reaction time, memory, and coordination. Gauging the neurobehavioral effects of toxicant exposure on human populations is particularly challenging, unlike measuring exposure, which can be done with biomarkers, biological sampling, and environmental sampling. Non-acute, sub-clinical deficits are perhaps the most difficult to characterize when it comes to human toxicant exposure. For most methods of testing, one needs an unexposed population to perform the tasks in order to compare the exposed populations. Behavioral tests, unlike other biomarkers of exposure, can integrate the toxic effects on neurological subsystems resulting in a more generally applicable test. They can also help fill the information gap between neurotoxicity testing on laboratory animals and frank neurotoxicity in the clinical setting after acute poisoning.


Background


With the support of the World Health Organization and the National Institute for Occupational Safety and Health two major neurobehavioral tests were developed in the 1980s, primarily for the investigation of occupational exposure to neurotoxins. The first set of tests, created in 1983, was the Neurobehavioral Core Test Battery (NCTB); the primary goal for this series of 7 neurobehavioral tests was to accumulate a database of chemicals classified by their neurobehavioral effects; the goal remains, as of yet, unattained. However, they still maintain the largest foundation of control data and have identified neurotoxic effects in the workplace. Another battery, the Neurobehavioral Evaluation System (NES), was developed on personal computers in 1985 and included computerized versions of 5 WHO NCTB tests (Anger et al 1997). The Agency for Toxic Substances and Disease Registry (ATSDR) developed the second major neurobehavioral battery in 1991 for U.S. residents living or working near hazardous waste named the Adult Environmental Neurobehavioral Test Battery (ARNTB) and included tests from the WHO NCTB and NES (Anger et al 1997). In the decade since the NCTB was created, a wider range of neurobehavioral effects caused by chemical exposures had been characterized. Also, because environmental exposures are generally much lower than those in the workplace, it was necessary that the ARNTB be a more sensitive neurobehavioral battery. The NCTB and ARNTB became the bell weather tests for evaluating neurobehavioral effects in the occupational and environmental exposure settings respectively (Johnson et al; Anger 2003).

Neurobehavioral Testing has been used to assess the effects of

  • Organophosphate Pesticides
  • Organic Solvents
  • Manganese
  • Fetal Alcohol exposure
  • Lead

    Advantages of Neurobehavioral Testing

    Disadvantages of Neurobehavioral Testing

    • Can detect group differences in the exposed group versus the unexposed group
    • Can be difficult to demonstrate that the deficit is caused by exposure neurotoxicity alone in individuals
    • Tests the sum of deficits and how they manifest in cognition, motor and sensory problems
    • There can be examiner bias or inappropriate testing vehicle for the given population
    • Identifies early signs of toxicity or neuropathy, which may allow for intervention especially
    • Require extensive effort to adapt to different populations and control for confounding factors
    • Large range of testing options allows for the characterization of low-dose effects as well as poisoning outcomes
    • Most research batteries cannot detect individual deficits


Current Neurobehavioral Batteries and Applications


  • The Functional Observational Battery (FOB) is used to identify frank neuropathy. It characterizes physical and movement defects, responses to environmental stimuli and other cognitive function.
  • The Bayley Scale for Infant Development is used to assess cognitive and motor function from 1 mo. to 3.5 years of age. This is useful to identify effects from prenatal exposures.
  • The Wechsler Intelligence Scale for Children is used with children 6 to 16 years of age. The tests is done without reading or writing, which accommodates the possible education levels of the target population.
  • The Behavioral Assessment and Research System (BARS) is a computerized battery with a simplified user interface. A battery can includes up to 11 tests, many of which can be taken in 5 different languages. It has been used with agricultural workers, adolescents, auto body workers, aluminum workers, and military service men and women. The computerized format reduces error introduced by human examiners.
  • The Neurobehavioral Core Test Battery (NCTB) is a paper-based series of tests meant for occupationally exposed populations. The tests have detected statistically significant differences between exposed and control groups in workplace research, administration required minimal training, and materials and equipment were inexpensive and could be administered in remote settings.
  • The Adult Environmental Neurobehavioral Test Battery (ARNTB) is used to characterize outcomes of a wide range of environmental exposures. It has been able to find statistically significant differences in performance between individuals who live near some hazardous waste locations and those who do not.

    Citations


Anger, WK, OJ Sizemore, SJ Grossmann, JA Glasser, R Letz, and R Bowler. "Human Neurobehavioral Research Methods: Impact of Subject Variables" Environmental Research. 73 (1997): 1-2. Print.

Anger, WK. "Neurobehavioural Tests and Systems to Assess Neurotoxic Exposures in the Workplace and Community." Occupational and Environmental Medicine. 60.7 (2003): 531-8. Print.

Johnson BL, Baker EL, El Batawi M, et al. Prevention of neurotoxic illness in working populations. New York: John Wiley & Sons, 1987.


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