Wormwood (Artemisia absinthium L.)--a curious plant with both neurotoxic and neuroprotective properties?

Abstract

The medical use of the wormwood plant Artemisia absinthium L. dates back to at least Roman times, while during the last century this tradition was seemingly on the decline due to fears of absinthism, a syndrome allegedly caused by the wormwood-flavoured spirit absinthe and more specifically as a result of thujone, a monoterpene ketone often present in the essential oil of wormwood. If threshold concentrations are exceeded, thujone does in fact exhibit neurotoxic properties leading to dose-dependent tonic-clonic seizures in animals, likely caused by GABA type A receptor modulation. Research has shown that the concentrations of thujone present in absinthe were not sufficient to exceed these thresholds, and the marketing of wormwood-flavoured alcoholic beverages has ultimately been reinstated. The declining fears of absinthism may have led to a revival of the medical uses of wormwood, evidenced by several experimental reports, e.g. on the treatment of Crohn's disease. Most recently in this journal, neuroprotective properties of wormwood were detected in rats, and the plant was suggested to be possibly beneficial in the treatment of strokes. While these results sound promising and worthwhile for further investigation, the well-defined profile of adverse properties of wormwood demands a more cautious interpretation of these results. It remained unclear in the studies, for example, if the threshold dose for thujone (e.g. as set by the European Medicines Agency) would be exceeded during therapeutic usage. Due to the colourful history of wormwood, its application in humans should be preceded by a thorough and careful risk-benefit analysis.