Testing for cognitive function in animals in a regulatory context.

Area of Science:

• Neuroscience
• Toxicology
• Risk Assessment

Background:

• Cognitive functions are crucial for human adaptation and survival.
• Chemical exposures can threaten cognitive capacities, leading to symptoms like confusion and forgetfulness.
• Complex animal tests for cognitive function have been used for decades but are rarely integrated into chemical risk assessments.

Purpose of the Study:

• To evaluate the assertion that cognitive functions are uniquely sensitive indicators of chemical exposure.
• To assess the necessity of animal models of cognitive function for detecting and quantifying chemical neurotoxicity.
• To compare the efficacy of complex cognitive tests with simpler screening methods in chemical risk assessment.

Main Methods:

• A systematic review of studies comparing complex (requiring training) and screening (no training) tests for assessing chemical neurotoxicity in rodents.
• Analysis focused on both adult and perinatal exposures, examining studies published since the early 1980s.
• Included 41 studies involving 35 distinct chemicals to compare acute effects.

Main Results:

• Complex tests identified neurotoxic effects of three chemicals (bitertanol, iso-amyl nitrite, Pfiesteria toxin) not detected by screening tests.
• For five additional chemicals, complex tests revealed effects at lower doses than screening tests.
• For developmental exposures, screening and complex tests showed equivalence for some chemicals (trimethyltin, PTU, elemental mercury), but screening tests were insufficient for others (PCBs, inhaled ethanol).

Conclusions:

• Complex cognitive tests can detect neurotoxic effects missed by simpler screening methods, suggesting they offer unique sensitivity.
• The necessity of complex tests for risk assessment requires balancing their unique detection capabilities against their high costs.
• Further discussion is needed within research and risk management communities regarding the utility and cost-effectiveness of complex cognitive testing.