Exploratory study on plasma Acylglycerol and Acylethanolamide dysregulation in substance use and attention-deficit/hyperactivity disorder: Implications for novel biomarkers in dual diagnosis

Substance use disorder (SUD) is a major global public health challenge, frequently co-occurring with psychiatric conditions such as attention-deficit/hyperactivity disorder (ADHD). Endocannabinoid system (ECS) dysregulation has been implicated in both SUD and ADHD, but the interplay between these conditions remains poorly understood. This study investigates plasma concentrations of endocannabinoid-congeners in individuals with SUD, with and without comorbid ADHD, to identify potential biomarkers. This exploratory study included 469 participants divided into three groups: (1) healthy controls (n = 136), (2) patients with SUD without ADHD (n = 267), and (3) patients with SUD and comorbid ADHD (n = 66). Plasma concentrations of 12 endocannabinoid-related molecules, including acylglycerols (2-AG, 2-LG, 2-OG) and acylethanolamides (AEA, DEA, DHEA, DGLEA, LEA, OEA, PEA, POEA, and SEA), were quantified using high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). A multinomial Elastic Net regression model was applied to assess their biomarker potential. Patients with SUD exhibited significantly lower plasma concentrations of 2-AG and 2-LG compared to controls, while most acylethanolamides were elevated, except for POEA and SEA. ADHD comorbidity was associated with lower concentrations of 2-AG, 2-LG, AEA, DGLEA, DHEA, and SEA, while PEA was elevated. Machine learning analysis identified AEA, OEA, PEA, and SEA as key biomarkers, achieving an accuracy of 72.1 % and an ROC-AUC of 0.77. This study suggests distinct ECS alterations in SUD and comorbid ADHD, highlighting endocannabinoid-congeners as potential biomarkers. Future research should validate these findings in larger cohorts and explore ECS-targeted therapeutic interventions for dual-diagnosis populations.