The chemical in question that reportedly causes the psychoactive effects is called Thujone. It's still debated right now, whether or not Thujone in sufficient concentrations can produce the "high" effects. Chemically Thujone is similar to THC, which is the element in weed that creates the "high".

I drank absinthe once in europe, it was about 80% alcohol, unknown thujone content, and I didn't get a "high" feeling. Got pretty drunk, but not "high".