Derry Crown Court has been told that a 50-year-old man who fired two crossbow bolts at a neighbour's house and attacked the front door with an axe was a cannabis addict who smoked up to 30 joints a day.
Brian Gerald Forbes, from Glenanne in the Brandywell area of the city, has admitted threatening to kill his US-born neighbour, causing criminal damage to his home and possessing an axe and crossbow in January 2017.
He carried out the attack after the men had a fall-out over an alleged loan of £1,000.
A prosecution lawyer said three independent medical experts agreed that Forbes suffered from a delusional disorder brought about by his cannabis use.
A defence barrister said Forbes had mental health issues dating back to 2006 and his cannabis use increased when, because of an accident, he could no longer work as a carpenter.
"Those who advocate that cannabis is a relatively harmless substance should be aware that it has caused substantial damage to this man's brain chemistry causing episodes of psychosis and of paranoid thoughts," he said.
Judge Philip Babington adjourned sentencing until next Monday and released Forbes on continuing bail.
