Chronic use of methamphetamine is associated with microglial activation in humans as visualized through PET imaging (Sekine et al., 2008), but another PET imaging study using TSPO as a biomarker, shows that cocaine abuse is not associated with microglial activation (Narendran et al., 2014). It’s not known if these differences in microglial activation are due to the different drugs of abuse or the use of different biomarkers. Acute LPS exposure in humans enhances methylphenidate-induced dopamine elevations in the dorsal striatum (Petrulli et al., 2017), indicating that systemic immune activation can also amplify the rewarding effects of drugs.
