Dr Chris Taylor, clinical psychologist and chief investigator on the trial, said: “We know that imagery has a more powerful impact on emotions and how we feel than just words alone.
“Imagine you’re somebody who’s suspicious with paranoia and you have a fear that someone’s going to break into your flat and attack you and hurt you.
“If you get a visual mental image of that as well, it makes you feel more anxious, more worried, worsens your paranoia.”
He said he hoped a full clinical trial would take place into the cost and clinical effectiveness of the treatment, and lead to it being used widely.
Mr Brandwood-Spencer said the therapy helped him separate the images from the “menacing feelings of threat” they caused.
“One of the most difficult aspects was the powerlessness and the idea that what was happening to me was permanent and inescapable,” he added.
“IMAPS helped me to address this, by changing this narrative of powerlessness.”
He now works in the substance use and mental health sectors, where he said he was “able to give people what I needed when it all began”.