[10] In vivo, FAAH is the principal catabolic enzyme for a class of bioactive lipids called the fatty acid amides (FAAs).

Members of the FAAs include: FAAH knockout mice display highly elevated (>15-fold) levels of N-acylethanolamines and N-acyltaurines in various tissues.

[24] Based on the hydrolytic mechanism of fatty acid amide hydrolase, a large number of irreversible and reversible inhibitors of this enzyme have been developed.

As a result, carriers of the A variant has increased N-acylethanolamine (NAE) levels and anandamide (AEA) signaling at the cannabinoid receptors.

The A variant may be responsible for lower levels of the FAAH protein seen in high-performing athletes, providing increased physical and mental fitness.

[51] A 2017 study found a strong correlation between national percentage of very happy people (as measured by the World Values Survey) and the presence of the rs324420 C385A allele in citizens' genetic make-up.

The study confirms that FAAH-OUT increases the expression of FAAH, both via its lncRNA product and through an intronic enhancer called FAAH-AMP.

[53] The enzyme is typically assayed making use of a radiolabelled anandamide substrate, which generates free labelled ethanolamine, although alternative LC-MS methods have also been described.

[9] Structures of FAAH with drug-like ligands were first reported in 2008, and include non-covalent inhibitor complexes and covalent adducts.