People who develop persistent psychosis from heavy, chronic ketamine use show the highest blood levels of neurofilament light chain (NFL), a marker of nerve cell damage, compared to ketamine users without persistent psychosis, people with schizophrenia, and healthy controls. NFL levels averaged 24.5 pg/mL in ketamine users with persistent psychosis, 12.9 pg/mL in those without, 9.2 pg/mL in schizophrenia patients, and 6.2 pg/mL in controls. Ketamine dependence was linked to higher NFL than schizophrenia, and the elevated NFL in those with persistent psychosis suggests a distinct neurobiological basis for this condition, even though its symptoms resemble schizophrenia.
Females with ketamine use disorder have lower leptin levels than healthy females, and those lower levels persist even after two weeks of abstinence. In contrast, males with ketamine use disorder show leptin levels similar to healthy males at the start of abstinence, and their leptin levels increase after two weeks of abstinence. Leptin is a hormone linked to addiction, and these sex-specific differences may be relevant for understanding recovery from ketamine dependence.