mind-altering drug

NOUN
18 LETTERS · STARTS WITH M

mind-altering drug is a valid 18-letter word worth 22 points in Scrabble and 29 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3I1N1D2-0A1L1T1E1R1I1N1G2D2R1U1G2
3 + 1 + 1 + 2 + 0 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 2 + 0 + 2 + 1 + 1 + 2 =22 PTS
DOUBLE WORD → 44TRIPLE WORD → 66
MEANING

What does mind-altering drug mean?