Behaviour...repetition of an action, a thought..reinforces the need for those and so after a time- a lie becomes a rationalisation becomes a truism becomes a truth.
Cognitive distortion- a drunk person thinks differently. A drunk person with brain changes- that are permanent from chronic drinking will at times say, do and think bizarre things because of the physiology changes in the brain's wiring.
Lying becomes a skill. It is easier to deny than to face shame or worse if there is theft violence, blah involved.
An alcoholic may tell a lie, believing it to be the truth. Some one at SR a while back posted her xah had just called her on his mobile phone- to tell her in an accusing and demanding voice- the he had lost his mobile phone (he only had the one).