Effects of Δ 9 -tetrahydrocannabinol on affiliative social behaviour: A systematic review of rodent studies
Mashal Ahmed, Christina F. Pereira, Laura M. Best, Raesham Mahmood, Tony P. George, Bernard Le Foll, Isabelle Boileau, Stefan KloiberIntroduction:
Affiliative social behaviour is critical for survival and well-being and is shaped by complex neurobiological systems, including the endocannabinoid system (ECS). Δ 9 -tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis, is a partial agonist at cannabinoid receptors and directly modulates ECS signaling. Given increasing cannabis use globally, understanding the effects of THC on social functioning is essential.
Methods:
We conducted a systematic review of preclinical studies indexed in MEDLINE and PsycINFO to examine the effects of THC on social behaviour in wild-type (WT) rodents and rodent social impairment models (SIM). Forty-nine studies encompassing 146 experiments were included. Risk of bias (RoB) was assessed using SYRCLE’s tool.
Results:
In WT rodents, THC generally reduced social behaviour, particularly following acute or adolescent exposure at moderate-to-high doses. SIM results were mixed: while low-dose THC sometimes improved social behaviour in schizophrenia-related models, higher doses often worsened deficits or had no effect. Outcomes varied by dose, sex, developmental timing, and experimental model. RoB assessment revealed insufficient reporting for nearly half of the included studies.
Conclusion:
These findings highlight the complexity of THC’s behavioural effects and suggest a need for more rigorous, sex-balanced preclinical research. Moreover, suboptimal methodological quality across studies hinders replicability and generalizability. More thorough and streamlined reporting is needed to support the translational validity of this area of research. As interest grows in ECS-targeted therapies for psychiatric disorders, understanding how THC modulates affiliative social behaviour under different conditions will be essential to inform safe and effective clinical strategies.