Assessing anxiety in nonhuman primates

Anxiety can be broadly described as a psychological state inwhich normally innocuous environmental stimuli triggernegative emotional expectations. Human anxiety disordersare multidimensional and may be organic or acquired, situationalor pervasive. The broad ranging nature of the anxietyphenotype speaks to the need for models that identify itsvarious components and root causes to develop effective clinicaltreatments. The cross-species comparative approach tomodeling anxiety disorders in animals aims to understandmechanisms that both contribute to and modulate anxiety.Nonhuman primate models provide an important bridgefrom nonprimate model systems because of the complexityof nonhuman primates' biobehavioral capacities and theircommonalities with human emotion. The broad goal of thisreview is to provide an overview of various proceduresavailable to study anxiety in the nonhuman primate, with afocus on the behavioral aspects of anxiety. Commonly usedmethods covered in this review include assessing animals intheir home environment or in response to an ethologically relevantthreat, associative conditioning and startle responsetests, and cognitive bias tests. We also discuss how theseprocedures can help veterinarians and researchers care forcaptive nonhuman primates.