An analysis of century-old bottles of absinthe - the kind once quaffed by the likes of van Gogh and Picasso to enhance their creativity - may end the controversy over what ingredient caused the green liqueur's supposed mind-altering effects .

The culprit seems plain and simple: The century-old absinthe contained about 70 percent alcohol, giving it a 140-proof kick. In comparison, most gins, vodkas and whiskeys are just 80- to 100-proof.

In recent years, the psychedelic nature of absinthe has been hotly debated. Absinthe was notorious among 19th-century and early 20th-century bohemian artists as "the Green Fairy" that expanded the mind. After it became infamous for madness and toxic side effects among drinkers, it was widely banned.

The modern scientific consensus is that absinthe's reputation could simply be traced back to alcoholism, or perhaps toxic compounds that leaked in during faulty distillation. Still, others have pointed at a chemical named thujone in wormwood, one of the herbs used to prepare absinthe and the one that gives the drink its green color. Thujone was blamed for "absinthe madness" and "absinthism," a collection of symptoms including hallucinations, facial tics, numbness and dementia.