One in 50 people is ‘highly likely’ to develop Alzheimer’s disease

One in 50 people are almost certain to develop Alzheimer’s disease, a study has found.

Researchers have discovered that almost all of those with two copies of a particular gene develop signs of the condition.

A team from the Sant Pau Research Institute in Barcelona analysed data from more than 10,000 people and more than 3,000 brain donors.

It revealed that more than 95 per cent of people aged 65 and above with two copies of the APOE4 gene went on to show early signs of the disease.

They also tended to develop the condition earlier than those with other variants of the gene.

Researchers said having two copies of APOE4 could be described as a distinct genetic form of Alzheimer’s. About two per cent of the population, or one in 50, carries two copies of this gene.

It could also help identify the best people to include in clinical trials for treatment.

In November 2022, Marvel film star Chris Hemsworth, 40, revealed that he carried two copies of the gene during his National Geographic series Limitless on human longevity.

Dr Juan Fortea, a research director at the Sant Pau institute, said: “These data represent a reconceptualisation of the disease.

“This gene has been known for over 30 years and it was known to be associated with a higher risk of developing Alzheimer’s disease.

“But now we know that virtually all individuals with this duplicated gene develop Alzheimer’s biology.”

The APOE gene comes in the variations APOE2, APOE3 and APOE4.

Everyone carries two copies of APOE, one inherited from each parent. Past studies have shown that having at least one APOE4 gene variant almost triples the risk of getting the disease.

The research showed that by the age of 65, almost all people who had two copies of APOE4 had abnormal levels of a protein known as amyloid in the fluid around the brain and spinal cord which is a sign of Alzheimer’s.

Dr Reisa Sperling, professor in neurology at Harvard Medical School, said: “We have to think about how we can treat APOE4 carriers.

“These individuals are desperate, they have seen it [the disease] in both of their parents.

“This research really suggests that we should be treating them quite early, at a younger age and at an early stage of pathology, because we know they are very likely to progress to impairment quickly.”

Prof Tara Spires-Jones, president of the British Neuroscience Association, said: “This study adds compelling data that people with two copies of this gene are almost guaranteed to develop Alzheimer’s if they live long enough, and earlier than people without this gene.”

Prof Jonathan Schott, chief medical officer at Alzheimer’s Research UK, said: “At present we do not advise that people have genetic testing for APOE except when taking part in research, but this may change in the future.

“At Alzheimer’s Research UK we are funding several research projects to try and understand why having the APOE4 gene increases the risk, and equally why some people with APOE4 do not develop dementia. We hope this work will lead to the development of new treatments and bring us closer to a cure.”

More than 900,000 in the UK are believed to be living with dementia, while the figure is believed to be seven million in the US.

However, Prof David Curtis, Honorary Professor, UCL Genetics Institute, said: “It has been known for decades that APOE4 is a strong risk factor for Alzheimer’s disease, that people carrying two copies are at high risk and that people carrying two copies are at substantially higher risk than those carrying one.”