A man who “self-medicated” his ADHD with cocaine died after taking a lethal amount of the drug.

Rory Brivio-Hughes, 23, was found dead on September 11 in his parents’ summerhouse in Shorncliff Road, Folkestone, after taking a concoction of legal and illicit drugs, an inquest heard.

Coroner Eileen Sproson ruled the pharmaceutical engineers’ death was caused by “intoxication by cocaine,” due to the high levels in his blood.

His mother Lisa Brivio-Hughes told Maidstone’s Archbishop’s Palace on Wednesday her son's death could have been avoided if his ADHD - Attention Deficit Hyperactivity Disorder - was diagnosed earlier.

"Rory being diagnosed with ADHD when he was about 20 is relevant in terms of drug use. He was diagnosed late.

“That's why he self-medicated we feel,” she said.

“He overcame lots of difficulties over the years and made really good progress. He was working abroad and came a really long way.

“We assumed he was in good mental health but obviously he wasn’t.

“People with ADHD often don’t want to share they are up and down and up and down.

“ADHD did probably contribute to his death - it is a relevant factor for us.”

The court heard Mr Brivio-Hughes had been seeing a private psychiatrist, Jeremy Beider from Psymplicity in London, to help cope with the condition.

“We assumed he was in good mental health but obviously he wasn’t..." - Lisa Brivio-Hughes, Rory's mother

Investigating officer DS Culpin said Mr Brivio-Hughes, who worked in Sweden with his father, visited friend of 10 years Joe Killick-Baker on the evening of December 9.

Mr Killick-Baker told police in a statement Mr Brivio-Hughes drunk almost a whole bottle of Courvoisier cognac.

He explained Mr Brivio-Hughes also consumed 200ml of codeine cough medicine, swallowed a number of unidentified blue pills, smoked cannabis, and may have “put something up his nose.”

He added Mr Brivio-Hughes’ drug tolerance may have been lower as he didn’t take drugs while working away in Sweden.

DS Culpin added Mr Killick-Baker’s partner Kelsey Green – who knew Mr Brivio-Hughes for three years – saw him consume four bottles of cider and four blue pills.

Her statement went on to say Mr Brivio-Hughes vomited a number of times outside at 3am, but that wasn’t unusual.

And when he was offered a place to sleep, Mr Brivio-Hughes opted to go home.

The court heard Mr Brivio-Hughes would stay in the summerhouse of his parents’ home at the bottom of the garden when he returned from Sweden.

Mr Brivio-Hughes’ sister Claudia Sawyers discovered him unresponsive in bed after the family were unable to contact him on September 10, the court heard.

The court heard DS Culpin attended the summerhouse on September 11, which was messy with evidence of drug use.

DS Culpin told the court he discovered a “large quantity of cannabis”, medicinal cannabis, blue pills and pharmaceutical medicine.

He added there was no evidence of third party involvement, or suggestion that Mr Brivio-Hughes took his own life – a suicide note for example.

The family were aware of Mr Brivio-Hughe’s cannabis use

A toxicology report found a “potentially fatal level of cocaine” in his system - 1.13mg per litre of blood.

The average reading for fatality ranges from 0.7 to 31mg, the court heard.

Morphine, cannabis and paracetamol were also discovered in Mr Brivio-Hughes’ urine.

It indicated the substances weren’t taken moments before his death, Ms Sproson said.