||While some people report little difference in the effects of Absinthe vs. other high alcohol content spirits, the presence of Thujone from Wormwood in many Absinthe preparations may alter the effects of alcohol.|
Wormwood oil (and therefore, authentic Absinthe) contains both alpha- and beta-Thujone. Beta-Thujone is less toxic and less potent than alpha-Thujone, and the pharmacodynamics of both substances appear to be similar. Therefore, as the more toxic constituent of Absinthe, alpha-Thujone is the focus of the majority of current research.
In an article discussing alpha-Thujone's mechanism of action, Hold, Sirisoma, Ikeda, and Narahasha (2000) found that alpha-Thujone was a modulator of the GABA-A receptor chloride channel. Under normal conditions, GABA binds to a postsynaptic neuron and allows chloride to enter the cell body. The influx of chloride causes hyper-polarization, or a "calming" effect on the neuron. Alpha-Thujone blocks this influx of chloride into the postsynaptic neuron, resulting in the "calming" inhibitory signals being blocked. This reduction in GABA-mediated inhibition results in excitation, which is why alpha-Thujone is classified as a convulsant and lowers seizure threshold.
The blocking of the usual GABA-A mediated inhibitory effects of alcohol may be the reason why Absinthe drinkers may be more talkative, appear less inebriated, and may drink more alcohol than usual, unintentionally. This can lead to dangerously high blood alcohol levels.
In other words, the alcohol and Thujone may work against each other on the GABA-A receptor, reducing some specific effects of alcohol intoxication.
The less-potent metabolites of alpha-Thujone are active as well, and may remain in the body for longer periods of time. It may be possible that residual activity by alpha-Thujone metabolites, in combination with alcohol withdrawal symptoms, could lead to seizures and possibly add to the mystique of absinthe in inducing both madness and bouts of creativity when consumed in large quantities over a long period of time.
After completing their research with mice, Hold et al. (2000) conclude that "Current low levels of alpha- and beta-Thujone in absinthe are of much less toxicological concern than the ethanol content" (Hold, Sirisoma, Ikeda, & Narahasha, 2000, p. 3831). However, the likelihood of drinking more alcohol than normally would be consumed may be a major risk factor associated with Absinthe consumption.
Hold KM, Sirisoma NS, Ikeda T, Narahashi T, Casida JE. "Alpha-thujone (the active component of absinthe): gamma-aminobutyric acid type A receptor modulation and metabolic detoxification." Proc Natl Acad Sci U S A. 2000 Apr 11;97(8):3826-31. [Link]