Formication and delusion of persecution occurs together in abuse with:

In cocaine psychosis formication occur along with delusion of persecution and is known as cocaine bug. Formication refers to the sensation of small animals crawling over the body. Cocaine is a natural stimulant derived from the leaves of coca plant. In the brain it increase the level of neurotransmitters like norepinephrine and dopamine. Regular use of cocaine can damage the brain circuit and produces a feeling of pleasure. Regular use of cocaine can result in arrythmias, stroke caused by spasm of blood vessels and respiratory arrest. Ref: Psychology: Concepts and Applications By Jeffrey S. Nevid page 165. Fish's clinical psychopathology : signs and symptoms in psychiatry 3rd edn, By Frank James Fish,page 25