The son of artist Alison Lapper was not ready to be helped when he died from a drug overdose, a coroner has concluded.
Penelope Schofield said Parys Lapper had "complex mental health issues" when he died in 2019, aged 19, at a hotel in Worthing, West Sussex.
But she said despite his mother's concern at a lack of help for him, there appeared to be no provision for people "who choose not to engage".
Ms Lapper said her son's death had left her feeling "ripped apart".
The coroner said there was no evidence Parys had taken his own life.
Parys, who was one of the children featured on the BBC's millennial "growing-up" series Child of Our Time, was found dead at the Wolsey Hotel in Worthing, just a few miles from the family home in Shoreham-by-Sea.
The inquest heard he had ingested heroin and diazepam.
In her narrative verdict, Ms Schofield said Parys had developed "an excessive use of illicit substances and prescribed medication" from an early age.
He had initially been under the care of child and adolescent mental-health services before switching to adult services after his 18th birthday.
Ms Lapper, who became a high-profile figure after posing nude, while pregnant with Parys, for a sculpture in Trafalgar Square, had previously criticised his "appalling" mental-health care since his secondary school days.
But addressing his mother, Ms Schofield said: "I do understand... that you feel aggrieved at the services for not doing more to protect your son, but having explored this, it does appear that there is no recognised provision out there for young people who misuse substances but who choose not to engage."
The coroner added: "Many people had tried to help him along the way, but for whatever reason, at the time of his death, he was not ready to be helped."
Ms Schofield said she would highlight in a 'prevention of future death' report how Parys had been able to "play the system" to obtain duplicate prescriptions to feed his addiction.
Speaking after the inquest about her dealings with mental health services, Ms Lapper told the BBC: "It felt like I was moaning and wasn't being listened to.
"You can't tell me, yesterday he was 17 and today you're 18 and you suddenly become an adult."
She added her son's death had robbed her of a "great relationship".