Animal models of psychosis

The creation of a valid animal model is of crucial importance to the study of the biological mechanisms underlying disease pathophysiology. This becomes difficult when studying psychiatric illness, most especially psychosis, as humans’ mental state is a strictly internally experienced phenomenon, and thus the biological readout of these conditions is often a behavioral assessment. Therefore, when designing appropriate animal model systems and behavioral assessments for the study of psychiatric illness, it is necessary that appropriate measures be taken to ensure the systems and tasks used fulfill rigorous demands of validity. This chapter discusses different forms of validity, expanding on the classical validity measures of face, predictive, and construct validity. Specific examples of behavioral assessments and animal preparations that adhere to these specific definitions of validity are presented. These include specific experimental paradigms that can be similarly assessed in humans with psychosis and animal models, methods to create an animal preparation based on known psychosis triggers and risk factors, and pharmacological means to demonstrate relevance to the human condition. The chapter argues for a systematic approach to design, verify, and validate an animal model system for research into psychosis specifically, and other psychiatric disorders more generally, based on these different classes of validity.