I heard that a certain hallucinogen called DMT can induce an abduction-like experience to the user. Not all users have the same kind of experience. About 20% of the test subjects experienced abduction experience when they took DMT.

I just wonder why that chemical substance, which is a schedule 1 drug and also naturally produced in our brains, cause such kind of experience? Some experiencers had a horrible hallucination about being eaten by a praying-mantis type being, which is common in UFO/Abduction lore.

Thats why its a drug. Not that great to talk about drug use with so many young children on this board.

But it's a naturally occurred substance in our brains, too. That makes a very complex issue with the substance.

Maybe a good suggestion/theory to disprove alien abduction testimonies?

Yep it is true, some people have reported meeting Mantis type beings under the influence of certain drugs.
link
It's too small a case study to be conclusive but interesting nevertheless. Could be a number of explanations.
Say from people who take drugs.. are, on a different higher level.. or they're just hallucinating...(most likely) or they're deluded and well versed on the abduction scenarios.
ie really want to believe.

Or maybe even... the aliens pick people on drugs, to be abducted, because there's less chance of them being discovered.

Electromagnetic stimulation of the brain has also been found to trigger similar experiences, but they depend on the person. Nuns saw the virgin Mary, other people saw Jesus, and others saw aliens. It was on TV a while ago, sorry. ^^;

Are you sure/ I just read, electromagnetic stimulation could just produce the feelings of a vague 'presence'
Not anything close to a polymodal Hallucination.

Perhaps that would be a better description than "saw", but the interpretations of the presence felt (I'm sure there were visual stimuli resulting too, if only perceived) were the same.