A man presents with olfactory, visual and auditory hallucinations

Why has this psychotic disorder suddenly manifested?

Hugh is a 44-year-old unemployed man with a childhood history of absence (petit mal) seizures.

He presents with a few months of bizarre olfactory, visual and auditory hallucinations.

He reports a heightened sense of smell, smelling carbon monoxide when he sits in public buses, being blinded by plastic sheeting in roofing, and having visits from green spirits that he feels could be aliens.

On examination, he has formal thought disorder and is very tangential.

He reports thought projection and delusions of reference, for example, that journalists on the television are communicating telepathically with him.

He also has paranoid ideation that the police are following and monitoring him.

He has had episodes of depersonalisation and derealisation.

He does not feel depressed, anxious or suicidal and denies using alcohol or illicit substances.

He has