Wo unto the liar, for he shall be thrust down to hell. Thrust by whom? The scripture doesn’t say. In God’s thrift, probably by the liar himself.
Bruce Charlton has argued that habitual dishonesty lowers your intelligence. Truth is light. Why would this be so?
Perhaps telling lies saps your brainpower since you have to devote much of it to running a simulation of the alternate reality your lie has created.
The prophets teach that the Holy Ghost withdraws from the liar. Truth is light; light is truth. So the liar isn’t enlivened by those pure strokes of intelligence.
Mostly, though, I would argue that lying is a form of rebellion against reality. Intelligence is contemplating and understanding reality, which the liar is less able to do since he resents it. You cannot ponder reality without submitting yourself to it, just as you can’t really think about God without already having submitted yourself in part.
Wickedness usually involves lieing to yourself. What we should expect, then, is that the wicked (i.e., all of us) are situationally dumb, because some things we can’t allow ourselves to think clearly about.