On the Proximate and Ultimate Explanations of Sex Differences in Anxiety and Anxiety Disorders

Abstract

During their lifetime, women are twice as likely to meet the diagnostic criteria for an anxiety disorder compared to men (Baxter et al., 2013). However, studies investigating the mechanisms underlying these sex differences often focus on different levels of analysis, making it more difficult to incorporate findings from these different studies. This article synthesises and reviews a selection of these analyses to provide a better-integrated representation of the mechanisms underlying sex differences. It uses the framework of four questions developed by Tinbergen in 1963, disentangling the potential proximate and ultimate mechanisms involved. This article describes the evidence for different explanations, with a particular focus on testosterone, which is presented as a possible link between different correlates of anxiety. Analysis of ultimate mechanisms include the evaluation of the optimality approach of behavioural ecology as well as the approach of evolutionary psychology. The signal detection theory suggests that some sex differences in anxiety may be adaptive, whereas the theories of evolutionary psychology suggest a mismatch between current and past environments in our species history. Overall, it is not supported that there would be a single explanation at any level of analysis.