Leptin levels and its correlation with crack-cocaine use severity: A preliminary study

•Drug use and appetite share some of the same brain reward processes.•Leptin may be modulating crack cocaine use.•Leptin was inversely correlated with the severity of crack use.•Leptin could be used as a biomarker for drug use. Crack-cocaine is an important public health problem in Brazil and worldwide. It is a potent form of cocaine which results in rapid and damaging stimulating effects on the central nervous system through inhibition of the dopamine transporter. Some studies have suggested that both food and drugs – including crack, can act on the same brain reward mechanisms, altering the dopamine pathways that modulate behavioral responses. Our hypothesis was that leptin, a well-known peptide that modulates energy metabolism and appetite, can be used as a biomarker for drug use. Anthropometric data, drug use profiles, and leptin serum levels were evaluated in a cross-sectional study of 40 crack-cocaine users. Leptin showed an inverse correlation with the severity of crack use, and this correlation remained when corrected by body mass index (BMI) and body composition by bioimpedance (BIA). The majority of subjects were eutrophic or overweight/obese considering BMI and BIA, and these variables were not significantly associated with the severity of crack use, but positively correlated with leptin levels. Our preliminary findings suggest that leptin could be involved in drug use severity, perhaps through pathways similar to those whereby it modulates food intake. Considering the anthropometric parameters, these findings provide additional evidence that low weight is not predominant in crack users.