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FAAH rs324420 Polymorphism in People With Opioid and Methamphetamine Use Disorders: Psychological Associations
Özlem Erekli-Arat1, Meltem Tepe1, Selin Özkan-Kotiloğlu1,2
1Institute of Forensic Sciences, Ankara University, Ankara, Türkiye.
Brain and Behavior
|May 15, 2026
Summary
The FAAH rs324420 CA genotype may protect against methamphetamine use disorder. This finding suggests a potential genetic factor influencing susceptibility to substance use disorders (SUD).
Area of Science:
- Neuroscience
- Genetics
- Pharmacology
Background:
- Substance use disorders (SUD) are a growing global health concern with increasing mortality rates.
- Methamphetamine use is rising, often concurrently with opioid use, leading to complex addiction patterns.
- The FAAH enzyme plays a role in endocannabinoid signaling and neurobehavioral processes relevant to addiction.
Purpose of the Study:
- To investigate the association between the FAAH rs324420 polymorphism and susceptibility to substance use disorders (SUD).
- To explore the potential protective or risk-conferring effects of specific FAAH genotypes on methamphetamine and opioid use disorders.
Main Methods:
- Genotyping of the FAAH rs324420 polymorphism using PCR-RFLP in 562 participants (methamphetamine users, opioid users, combined users, and controls).
- Assessment of psychological and clinical measures including impulsivity, withdrawal symptoms, craving, anxiety, and depression.
- Statistical analysis to determine genotype frequencies and their association with SUD risk.
Main Results:
- The FAAH rs324420 CA genotype was associated with a significantly reduced risk of SUD (OR = 0.578, p = 0.039).
- Allele frequencies varied across groups, with 21% in opioid use disorder (OUD), 13% in methamphetamine use disorder (MUD), 16% in combined use (OMCU), and 19% in controls.
- Higher craving scores were observed in individuals concurrently using opioids and methamphetamine compared to opioid-only users.
Conclusions:
- The FAAH rs324420 CA genotype may offer a protective effect against developing methamphetamine use disorder.
- These findings highlight a potential genetic influence on SUD, particularly for methamphetamine addiction.
- Further research with larger cohorts and diverse populations is warranted to validate these genetic associations.
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