The effects of neurotoxins on cognitive function: Towards a theoretical approach

It is now well established that cognitive impairment can be detected at concentrations of a neurotoxin below those producing harmful effects on other organ systems. The importance of this sensitivity lies in the yet untested belief that it affords benefits in the early detection of later dysfunction arising from either prolonged or elevated exposure. From this preventative perspective it is essential to evolve psychological techniques to specifically target functions suspected as crucial to the impairments observed and the cognitive approach provides the necessary degree of sensitivity and specificity for targeting functions and characterizing states of marginal toxicity. The strength of the cognitive approach lies in two main areas: the well-founded theoretical framework that exists for characterizing cognitive subsystems and the application of cognitive models to detecting the functional changes associated with diverse activities that normally lie outside the domain of neurotoxicology. The insights gained from this work needs to be incorporated and embedded into the general framework for neurotoxicology work so that theoretically motivated achievements can foster and encourage reciprocal advances. Isolating neurotoxicological investigations from these major developments only serves to hamper progress while the potential gains are immense. It is concluded that an increased reliance on a theoretical framework for conducting neurotoxicological work is essential to the continued health of neurotoxicological research. However, an improved ability to detect marginal states of toxicity brings with it a range of additional, but nevertheless, important issues. Perhaps the most important of these relates to the impact that research findings have on the legislative processes that many governments have enacted to preserve the health of populations working with potentially neurotoxic substances. One emerging approach in this area is that of benchmarking - a process by which the effects of a neurotoxin are compared to that of a more familiar condition. A variety of benchmarking models is currently under consideration and some of the issues facing both researchers and regulators in developing this approach will be addressed. Bringing these diverse areas into contact will aid in the provision of a more convincing account of dysfunction and support action on a chemical regulatory level that will benefit workers.