A web designer killed himself after being driven mad by cannabis.

Daniel Rosen hanged himself from a tree after becoming mentally ill after years of smoking the Class C drug.

Yesterday the 28-year-old's family said they were convinced smoking cannabis from the age of 14 had cost him his life.

Sue Rosen said the drug had "triggered something which went wrong in his mind".

In August The Argus told the story of "Craig", a teenager who had become a paranoid recluse on the edge of madness after years of smoking cannabis.

The 19-year-old, who quit drugs after treatment at The Priory Centre in Hove, became obsessed with using the drug.

And last night anti-drug campaigners warned the death of Mr Rosen showed the dangers of cannabis.

Jane Harris, the head of campaigns at mental health charity Rethink, said: "There is a definite link between smoking cannabis and mental illness.

"If you use cannabis heavily, or if you use it under while you are under 18, it can double your chances of suffering from mental illness.

"We want the Government to put more money into researching that as there has been no UK-funded primary research only a review of others."

An inquest at Brighton yesterday heard how Mr Rosen, of Blaker Street, Brighton, was found hanged in a wooded area of Stanmer Park, Brighton, on the morning of December 12 last year by a dog walker.

Beside him was a rucksack containing books on Krishna and notes he had made about his thoughts and feelings.

A post mortem examination of his body confirmed he had died of asphyxiation due to hanging.

His parents described the self-employed designer as intelligent, creative, talented and a gentle young man who wanted to make people happy and who loved animals.

But they also said he was a tortured soul and was suffering from mental illness.

The inquest was told Mr Rosen was referred to the mental health service in April 2004 by his doctor and was prescribed medication which he would not always take.

His psychiatrist, Dr Timothy Sayles, said Mr Rosen was vulnerable to psychosis which was exacerbated by stress but that he was not bipolar or schizophrenic. He also said Mr Rosen had no history of suicidal thoughts.

But by 2007, he said Mr Rosen was steadfast in his beliefs that what we happening to him was a spiritual experience.

Last year he was admitted to Mill View Hospital in Hove under the Mental Health Act but he was deemed well enough to be discharged on August 14 and it was not until Mr Rosen's family got in touch with the hospital in November that he was asked him to come back for a review.

Mr Rosen produced a letter for doctors featuring the signatures of his parents which said they were no longer worried about him.

But his mother told the inquest her son and written the letter himself and they had signed it under 'extreme pressure' from him.

She said her son had expressed a desire to travel and twice they had paid for him to go on holiday. The first time they had paid for a trip to Norway but Mr Rosen never made it to the airport and the second time they had paid for him to go to a spiritual retreat in Wales but the holiday was a disaster and he returned days later in an angry and distressed state.

In December he returned to the family home in Reading for the Jewish festival Hanuka and his family thought he seemed more grounded.

Mrs Rosen said: "We talked about him travelling and he said he wanted to go somewhere warm and he needed some sun.

"We booked a ticket for him to go to Egypt and he was due to go two days after he died.

"The evening before his death I actually spoke to him and I was a little bit anxious as a parent as he had chosen to go to Egypt. What with being Jewish I didn't think it was the wisest place to go and I said be careful and he did say, 'I am frightened'."

Brighton and Hove coroner Veronica Hamilton-Deeley recorded a verdict of suicide and said Mr Rosen may well have had a period of improvement or he may well have had a period of decision, taking his life back into his own hands.

She also read part of his funeral eulogy to the court which had been written by his parents.

It said: "It seems in his final few weeks he was getting more in touch with the reality of his situation, was becoming aware of how fragmented his mind and his life actually were and this was extremely painful, unbearable, for him.

"And so he ended his life, in a beautiful park in Brighton, in a natural place that gave him comfort, with a red-breasted robin as his companion. He did not die alone but had the natural world as his companion.

"His parents and sisters, his family and friends, can and should take comfort that he is now at peace and nothing can cause him pain again."