A teenager who died after ingesting lethal quantities of water while being detained in hospital for psychosis was let down by a number of failings in his care, according to a watchdog.

A review of the tragedy by the Mental Welfare Commission (MWC) for Scotland found that the 18-year-old patient - known only as Mr D - was able to "engage in risky and ultimately fatal psychosis-driven behaviour" because the ward staff treating him during his final admission had not been provided with relevant case files.

Mr D, who died in December 2018, had been transferred to an adult mental health service (AMHS) unit in a neighbouring health board as there were no inpatient beds available in his local area.

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He spent 70 hours in the unit - which is not named in the report - before staff noticed that his bedroom floor "was wet and he had vomited clear mucus-like fluid" on the evening of December 7 2018.

It added: "He stated that he had drank water, before suffering a seizure and rapidly deteriorating.

"Paramedics swiftly transferred Mr D to the acute hospital intensive care unit but he did not recover and died on December 10 2018."

The review details how Mr D had first developed behavioural difficulties as a young teenager as a result of smoking cannabis.

Aged 16, following the onset of psychotic symptoms, he was admitted to an acute hospital intensive care unit suffering from a seizure brought on by water intoxication.

Ingesting a very large amount of water over a short period can be dangerous because it disrupts the body's electrolyte balance, leading to confusion, disorientation, nausea, and vomiting.

The kidneys are only able to remove between 800ml and one litre of water from the body per hour.

In rare cases, water intoxication can cause swelling in the brain and become fatal.

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Following this first incident, the 16-year-old Mr D was transferred to a regional Child and Adolescent Mental Health Service (CAMHS) inpatient unit for psychiatric treatment.

He was detained again in 2017 for psychotic symptoms, which were described as resembling bipolar disorder with signs of schizophrenia.

The report said that Mr D had been treated with three different antipsychotic medications but there were periods of up to eight months when he was "known to refuse treatment".

It added: "In the year before Mr D’s death, his parents raised concerns about the extent of his ongoing psychotic symptoms and the behaviours he displayed in association with his illness.

"They thought their son’s treatment with medication was not optimised and were concerned about it being delivered voluntarily, when he was so clearly affected by psychotic illness."

This included fears that he "would die by his own hand" as a result of risky behaviour.

When he was admitted to an out-of-area hospital again as an adult in December 2018, case notes from his previous contact with CAMHS "were unavailable".

While relevant clinical information was passed to his new treatment team in the form of letters, telephone calls and past detention papers, and face-to-face meetings and phonecalls were held between Mr D's parents and his receiving general adult consultant psychiatrist, "not all of this valuable clinical information made it into [Mr D's] care plan".

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The MWC has issued 10 recommendations following its review of the case. 

Suzanne McGuinness, its executive director (social work), said: “This was a tragic death of a young man while he was being cared for in hospital.

“Our report details the actions and decisions taken by teams at the two health boards involved in the lead-up to his death.

"We found that a more assertive approach to the treatment of Mr D’s psychotic illness in the two years before his death was warranted. The risks associated with psychotic illness were not coherently managed.

“We also found that there were problems in Mr D’s transition from child and adolescent mental health services to adult mental health services. Existing guidance was not adhered to.

“We found that although the service had no other viable option, the transfer of a very unwell young man with a complex clinical history to another health board area during the night was a high-risk action.

“Mr D’s family told us they felt that they had not been listened to. They felt their concerns were not given due credence.

“We ask mental health services across Scotland to read this report, consider our findings carefully, and take action where they believe they can make improvements."