Yesterday, Mrs Roberts told the Liverpool inquest her son was pleasant, cheerful and happy, but the week before his death had behaved oddly, going for a drive in the early hours of the morning and losing his appetite.
"There was no indication he was planning to take his own life," she said, adding he had been happy because his skin was being treated.
Dermatologist Dr Hazel Bell, one of his doctors, said he "was not clinically depressed four weeks before death".
Dr Cosmo Hallstrom, a consultant psychiatrist, said there was not enough of a link between Roaccutane and self harm.
In a narrative verdict, Liverpool coroner Andre Rebello said: "There is no causal connection between Roaccutane and the medical cause of death. It is right to ask the questions."
Royal Liverpool and Broadgreen University Hospitals Trust issued a statement saying: "Roaccutane has a known rare side-effect of depression in a very small number of patients.