The relationship between craving and insular morphometry in regular cocaine users: Does sex matter?

While it has been suggested that cocaine use and relapse in women is more strongly related to stress-relief craving, whereas cocaine use in men is more strongly related to reward craving, the neural mechanisms that underlie these differences are poorly understood. The aim of this study was to investigate sex-dependent differences in insular morphometry and associations with craving, in a sample of regular cocaine users (CUs) and non-drug using controls (non-CUs). It was hypothesized that insular volume, thickness and surface area would be lower in CU women, compared with CU men and non-CUs. It was furthermore hypothesized that insular morphometry, particularly insular thickness, would be negatively associated to reward craving in CU men, while being negatively associated with stress-relief craving in CU women. In contrast to the hypothesis, we did not find evidence of sex-specific differences in insular morphometry in CUs. However, sex-specific association between stress-relief craving and insular morphometry were found: Right insular volume was negatively associated with stress-relief craving in CU women, whereas this association was positive in CU men. Additionally, right insular surface area was negatively associated with stress-relief craving in cocaine-using men, whereas this association was positive in cocaine-using women. In conclusion, the current study provides first evidence of sex-specific differences in the association between craving and insular morphometry in a sample of regular cocaine users. Although speculative, these sex-specific alterations in insular morphometry may underlie higher stress-induced craving and relapse in CU women compared with CU men.