A PET study linked cingulate D2/D3 receptor availability with working-memory performance in stimulant use disorder. It could not establish a receptor-availability deficit relative to its own controls because those controls did not undergo PET.
The research included 84 adults with stimulant use disorder—74 with methamphetamine and 10 with cocaine use disorder—and 47 controls. All completed a spatial-capacity delayed-response task. A subset of 52 stimulant-group participants underwent PET with fluorine-18 fallypride. This was observational human research, not administration of a dopamine-enhancing treatment.
After adjustment for demographics and estimated intelligence, the stimulant group performed worse on the working-memory task. Within the PET subset, better performance was associated with greater D2/D3 availability in cingulate cortex after correction. Fallypride does not distinguish the D2 from D3 subtype, so the result cannot be assigned exclusively to either. The tracer measurement is also different from a direct assay of dopamine release.
Because PET data were absent in controls, the study’s own working-memory group difference cannot be matched to a demonstrated PET group difference. Prior studies can provide context but do not supply missing observations in this cohort. The mixed stimulant group was predominantly methamphetamine-related, and a within-group correlation cannot prove that increasing receptor signaling would improve cognition or treatment outcome. Neither task performance nor receptor availability establishes individual impairment during an earlier event. The study identifies a treatment hypothesis and an association to replicate, while preserving the limits of the actual imaging comparison.
See dopamine-related PET findings in a different clinical population.