/cloudfront-eu-central-1.images.arcpublishing.com/prisa/URM2I4EENBHORGL6JWSFZ5NEXQ.jpg)
It was an inadvertent experiment with tragic results.
Thousands of short people around the world received growth hormones extracted from the pituitary glands of cadavers.
The treatment was stopped around 1985, when it was discovered that these intramuscular injections could transmit the prions that cause the lethal Creutzfeldt-Jakob disease, similar to mad cow disease.
A new study now reveals another unwanted effect of those therapies.
A team from University College London believes that treatments with pituitary hormones – a pea-sized gland at the base of the brain – transmitted Alzheimer's to five people in the United Kingdom.
They would be the first known cases of accidental transmission of the disease.
Some 55 million people in the world suffer from dementia, linked to Alzheimer's in most cases.
The disastrous inadvertent experiment could illuminate the enigmatic mechanisms of the disease, which still lacks an effective treatment.
In the brains of deceased patients, it is common to find abnormal accumulations of two proteins: beta amyloid and tau.
The same researchers, led by neurologist John Collinge, already warned in 2015 that they had detected suspicious amyloid beta plaques in the brains of six people who died from Creutzfeldt-Jakob disease after receiving growth hormones.
In 2018, they detected beta amyloid in batches of the hormone stored for decades and found that these proteins caused dementia in laboratory mice.
More information
The enigma of Alzheimer's: its incidence falls by 16% every decade without any drug
Collinge's team is convinced they have found the first five known cases of accidental transmission of Alzheimer's.
All those affected received growth hormones from cadavers, often for years, and began showing symptoms of dementia when they were between 38 and 55 years old, despite lacking the genetic variants present in other early cases.
The finding is announced this Monday in the specialized journal
Nature Medicine
.
The first signs of 2015 unleashed global alarm, due to some erroneous headlines, especially in the tabloid press.
The British tabloid
Daily Mirror
proclaimed on its cover: “Alzheimer's can catch you.”
Collinge's team now emphasizes that cadaver hormone treatments were phased out decades ago and that “there is no evidence that beta amyloid can be transmitted in other contexts, for example, during activities of daily living or when providing care.” routine.”
The authors, however, invite us to review the measures in force to avoid the accidental transmission of Alzheimer's in invasive surgical procedures.
“The main concern is the instruments used in neurosurgery, we must ensure that they are decontaminated,” Collinge explains to EL PAÍS.
An international study carried out a little over a decade ago found 226 cases of Creutzfeldt-Jakob disease caused by treatments with growth hormones from cadavers.
Epidemiologist Fernando García López explains that no cases have been reported in Spain, despite the fact that more than a hundred have already been detected in neighboring France.
García López, from the National Center for Epidemiology, details that in Spain there have been eight cases of Creutzfeldt-Jakob disease caused by dura mater implants – one of the membranes that protect the brain – after brain tumor operations.
Since 1987, the epidemiologist explains, the dura mater obtained from cadavers began to be treated with caustic soda and the problem disappeared.
Alzheimer's is not contagious
Pascual Sánchez Juan, neurologist
Almost 2,000 people in the United Kingdom received growth hormones obtained from cadavers between 1959 and 1985. To date, about 80 cases of Creutzfeldt-Jakob disease caused by these treatments have been observed.
What would be expected, the researchers argue, would be to find more cases of Alzheimer's in this group of patients.
Epidemiologist Fernando García López recalls that in Spain there is a surveillance system implemented since 1995, which analyzes whether patients with Creutzfeldt-Jakob disease received growth hormones decades ago.
“We should have detected them.
Why has France had 119 cases and we have none?
It is a mystery,” he points out.
John Collinge's laboratory already demonstrated in 1996 that the new variant of Creutzfeldt-Jakob disease was caused by the same strain of prions—abnormal transmissible proteins—that caused mad cow disease.
The British neurologist believes that there are lessons learned from this prion disease that can be applied to Alzheimer's.
Collinge and his colleagues hypothesize that beta amyloids do not respond to a single profile, but rather are “a cloud of diverse species,” as occurs with prions.
Ignoring this heterogeneity could facilitate the emergence of resistance to the first drugs against Alzheimer's.
The neurologist Pascual Sánchez Juan is blunt.
“Alzheimer's is not contagious.
Dealing with patients in their homes or in nursing homes does not involve any risk”, he reassures him.
Sánchez Juan is the scientific director of the Neurological Diseases Research Center Foundation, in Madrid.
“If we are able to know the specific strain, we will be able to better direct the treatment of each patient, but we have not yet been able to correlate this diversity of beta amyloid plaques with the different clinical subtypes of Alzheimer's disease,” he laments.
The expert, from the Spanish Society of Neurology, is optimistic: “Alzheimer's probably arises from many causes, but there are many mechanisms that we do not know.
This new study is an unrepeatable scientific experiment.
They unintentionally injected the pathology into the patients.
Now they will be able to clarify things that would otherwise be impossible.”
You can follow
MATERIA
on
,
X
and
, or sign up here to receive
our weekly newsletter
.