Half of children taking ‘miracle drug’ for cystic fibrosis may suffer from severe mood swings, study finds

A cystic fibrosis drug dubbed “the holy grail” by doctors can cause mood swings, behavioral problems, insomnia and thoughts of suicide in children as young as three, disturbing research has found.

The drug, Kaftrio, which was approved for full NHS rollout last month, eases the worst symptoms of the genetic disease and is expected to significantly improve life expectancy.

But a new study, published last week in The Lancet, makes clear that the drug can affect mental health. Researchers gave doses of the drug to 197 children aged two to five. After a month, 93 of them — 47 percent — were reported to have shown sudden, abnormal changes in behavior.

A third developed attention deficit hyperactivity disorder (ADHD), which causes poor concentration, irritability and impulsive behaviour. Others became aggressive. One in 10 developed ‘abnormal sadness’ and one had suicidal thoughts. These changes persisted in 58 of the 93 children and stopping treatment led to an ‘immediate recovery from symptoms’.

It is unclear why the drug might cause mental health problems, or who would be most affected.

French scientists behind the Lancet study speculate that it could tip the balance of chemicals in the brain involved in feelings of anxiety and depression. They believe caution should be exercised in prescribing the drug to children until there is a better understanding of what the drug does in the body.

Cystic fibrosis (CF) is a lifelong genetic disorder that causes the body to produce thick mucus that clogs the digestive tract and causes lung infections. In the 1970s, few patients survived beyond their teens – now about half make it to age 40.

Patients, who are often hospitalized due to the effects of the disease, call Kaftrio “almost a cure” because it helps them live normal lives. But since it became available in 2020, stories of psychiatric problems have emerged.

Two years ago, The Mail on Sunday was the first to raise the alarm after adults with CF came forward with a range of symptoms they said were caused by the pills, including severe depression, debilitating brain fog and memory problems.

It’s unclear why the drug might cause mental health problems, or who is most affected (stock photo)

A woman in her early 30s began experiencing extreme anger and depression, migraines, seizures and temporary paralysis. In two shocking cases reported by this newspaper in 2022, a woman attempted suicide and a nine-year-old boy with no history of mental health problems began self-harming after being started on similar medications.

At the time, healthcare professionals and the CF Trust suggested that these problems could be due to the life-changing nature of the treatment – ​​not the drug itself. However, following our reports, patient information leaflets in Kaftrio packs were updated to include depression as a possible side effect.

Kaftrio, and similar drugs Symkevi, Orkambi and Kalydeco, are known as CFTR modulators because they correct a fault in a gene called CFTR that causes the most debilitating symptoms of CF. They are all made by the US pharmaceutical company Vertex.

A company spokesman said last night: ‘We have conducted a thorough analysis of all available data and based on this comprehensive review we find no causal association between Kaftrio and psychiatric events. Nor do we find a causal association between Kaftrio and depressed mood, sleep, concentration and memory problems or challenging behaviour in children and young people.’

Kaftrio, and similar drugs such as Symkevi, Orkambi, and Kalydeco, are known as CFTR modulators because they correct the error in a gene called CFTR that causes the most disabling symptoms of CF

We contacted the mother of the nine-year-old child, who had previously spoken to the MoS about the side effects her son was experiencing from taking Symkevi and Kalydeco.

She said the drugs had caused her “happy” boy to become constantly tearful, and she later discovered he had begun scratching his face and arms with a razor.

His advisor agreed that he should stop taking the medication and he soon recovered.

The boy is now 11, and last summer he started taking Kaftrio. His mother says: ‘The problems started almost immediately when he started taking the medication – it was like a turning point. He went from being a happy, cheerful, confident boy who loved football to being a crying, angry boy. And the self-harm came back, which is terrifying.’

Once again the medication was reduced and he was soon back to his old self.

‘I’m in a Facebook group for parents of children with CF. There are endless posts about behavioral problems. I can’t help but think it’s because of Kaftrio.’

David Ramsden from the CF Trust said the effects of Kaftrio are positive for most, but ‘we know this is not the case for everyone’.