The short and sweet version of what kava does to cause the psychological effects we are accustomed to. Each one of these topics are an entire paper to themselves so this paragraph represents volumes of scientific research.
"The pharmacological properties of kava are postulated to include blockade of voltage-gated sodium ion channels, enhanced ligand binding to γ-aminobutyric acid (GABA) type A receptors, diminished excitatory neurotransmitter release due to calcium ion channel blockade, reduced neuronal reuptake of noradrenaline (norepinephrine), reversible inhibition of monoamine oxidase B and suppression of the synthesis of the eicosanoid thromboxane A2, which antagonizes GABAA receptor function."
Singh YN, Singh NN. Therapeutic potential of kava in the treatment of anxiety disorders. CNS Drugs. 2002;16(11):731-43. doi: 10.2165/00023210-200216110-00002. PMID: 12383029. https://pubmed.ncbi.nlm.nih.gov/12383029/
"The pharmacological properties of kava are postulated to include blockade of voltage-gated sodium ion channels, enhanced ligand binding to γ-aminobutyric acid (GABA) type A receptors, diminished excitatory neurotransmitter release due to calcium ion channel blockade, reduced neuronal reuptake of noradrenaline (norepinephrine), reversible inhibition of monoamine oxidase B and suppression of the synthesis of the eicosanoid thromboxane A2, which antagonizes GABAA receptor function."
Singh YN, Singh NN. Therapeutic potential of kava in the treatment of anxiety disorders. CNS Drugs. 2002;16(11):731-43. doi: 10.2165/00023210-200216110-00002. PMID: 12383029. https://pubmed.ncbi.nlm.nih.gov/12383029/