BACKGROUND AND AIMS Impairments in social cognition and social decision-making play an important role in the disease burden experienced by individuals with methamphetamine use disorder (MUD). They are also assumed to play a role in the vicious cycle of MUD development and hinder its successful psychotherapy. However, research typically focuses on examining specific types of social cognitive deficits in MUD, rather than profiling the multidimensional social cognition and decision-making impairments that coincide with MUD. Our study, thus, estimated the socio-cognitive and social decision-making profile of people with MUD and compared this profile with a methamphetamine-naïve control group.

DESIGN Cross-sectional case-control comparison of social cognition and decision-making between participants with MUD recruited from clinical services and methamphetamine-naïve controls (CTRL) recruited from the community.

SETTING Drug treatment clinics in Melbourne, Australia.

PARTICIPANTS 52 participants with MUD (moderate or severe; 77% identified as male) between April 2019 and September 2021 and 51 demographically matched CTRLs (no history of methamphetamine use; 54% identified as male) between May and September of 2021.

MEASUREMENTS We implemented a social cognition battery that assessed a participant's sensitivity for perceiving emotion from faces (emotion recognition) and their ability to detect accurately the emotional state of others (cognitive empathy) and experience the emotions of others (emotional empathy). We also characterised the propensity to engage in higher-order social decision-making by assessing a participant's willingness to engage in interpersonal trust and aggression in experimental simulations.

FINDINGS Compared with matched controls, people with MUD had a bias toward perceiving happier facial expressions as neutral [Estimate = -5.05, standard error (SE) = 2.05, P = 0.016, 95% confidence interval (95% CI) = (-9.12 to -0.98)], showing lower sensitivity to perceiving happy emotions [Estimate = -6.34, SE = 3.09, P = 0.043, 95% CI = (-12.47 to -0.20)]. People with MUD also showed a propensity to enact more intense punishments [Estimate = 1.48, SE = 0.38, P < 0.001, 95% CI = (0.73-2.23)] and lower levels of trust to others in their decisions [Estimate = -0.11, SE = 0.04, P = 0.002, 95% CI = (-0.18 to -0.04)].

CONCLUSIONS In a clinical research study, people with methamphetamine use disorder appeared to show lower sensitivity to happy emotions, reduced trust and increased aggression toward others, relative to a matched control group.