Two other PET investigations examined SG differences in the opioid system in AUD, as opioid receptors have been implicated in AUD (Crowley & Kash, 2015; Mason, 2017; Mitchell et al., 2012). Using the selective kappa opioid receptor (KOR) antagonist radiotracer, [11C]LY2795050, adults with AUD had lower KOR availability than healthy controls in the amygdala and pallidum (A. Vijay et al., 2018). Exploratory analyses suggested that adult men with AUD had lower KOR availability than healthy adult men in 9 regions, whereas adult women with AUD had lower KOR availability in the amygdala compared to healthy adult women (A. Vijay et al., 2018). In this study, comparison of AUD women to healthy women was underpowered to detect differences in multiple regions, underscoring the need to recruit more women. For perspective, in a sample of healthy adult individuals, men had higher KOR availability than women in multiple brain regions, including the anterior cingulate cortex (ACC), frontal cortex, and insula (Aishwarya Vijay et al., 2016), suggesting that differences in KOR are related to sex differences and not simply a question of sample size.
