Associations between methamphetamine use disorder and SLC18A1, SLC18A2, BDNF, and FAAH gene sequence variants and expression levels

Introduction: Assessing candidate gene sequence variations and expression helps to understand methamphetamine use disorder and inform potential treatments. We investigated single nucleotide polymorphisms (SNPs) and gene expression in four candidate genes: SLC18A1, SLC18A2, BDNF, and FAAH, between controls and people with methamphetamine use disorder. Methods: Fifty-nine participants (29 people with methamphetamine use disorder and 30 controls) completed a clinical interview, cognitive tasks, and provided a blood sample. SLC18A1, SLC18A2, BDNF, and FAAH SNPs were genotyped, and gene expression was assessed with real-time quantitative PCR. Results: SLC18A1 Pro4Thr was associated with methamphetamine use disorder (OR = 6.22; p =.007). SLC18A2 variants, rs363227 and rs363387, were negatively associated with methamphetamine use severity (p =.003) and positively associated with inhibitory control performance (p =.006), respectively. BDNF Val66Met was associated with the severity of use (p =.008). SLC18A2 and FAAH mRNA levels were lower in people who use methamphetamine relative to controls (p =.021 and.010, respectively). Conclusions: SLC18A1 is identified for the first time to play a potential role in methamphetamine use disorder. Lower levels of blood SLC18A2 and FAAH mRNA in people with methamphetamine use disorder suggest reduced monoamine reuptake, recycling, or release, and higher anandamide levels in this clinical group, which may be potential therapeutic targets.