Dementia starts in the WOMB

Does dementia start in the WOMB? Memory-robbing disorder may be caused by ‘spelling mistakes’ in DNA when patients are just an embryo

• May explain why only one in 20 patients has a family history of the disease
• Mutations occur spontaneously in the womb rather than being inherited
• Leads to ‘islands’ of mutated brain cells that may be common among the public  

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Dementia may start in the womb, research suggests.

Mutations that lead to the disease can occur in DNA as the brain cells of embryos divide, a Cambridge University study found.

Researchers believe the findings offer hope of new treatments for dementia, as the world of science continues their quest to find a cure. 

They hope they could explain why so many people develop dementia – even when the individual has no family history.

Professor Patrick Chinnery, who led the trial, said: ‘These spelling errors arise in our DNA as cells divide.’ 

Dementia may start in the womb. Mutations that led to the disease can occur in the brain cells of embryos, which may explain why few patients have a family history of the disease (stock)

The researchers analysed 173 brain tissue samples from the Newcastle Brain Tissue Resource; part of the Medical Research Council’s UK Brain Banks Network.

The samples came from the brains of 54 people. Of which, 14 were healthy, 20 had Alzheimer’s and 20 had Lewy body dementia.

Lewy body dementia occurs when tiny protein deposits occur in the nerve cells of the brain. It is thought to affect more than 100,000 people in the UK and 1.3 million in the US.

‘As the global population ages, we’re seeing increasing numbers of people affected by diseases such as Alzheimer’s, yet we still don’t understand enough about the majority of these cases,’ Professor Chinnery said.

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‘Why do some people get these diseases while others don’t? We know genetics plays a part, but why do people with no family history develop the disease?’ 

To answer this question, the scientists assessed 102 genes in the sample brain cells more than 5,000 times using computer technology.

These genes included those that are known to increase a person’s risk of dementia.

Results showed 27 of the 54 brains contained spontaneous mutations, which means they were not inherited.

The researchers believe these mutations came about when the patient was just an embryo developing in the womb.

The DNA changes discovered were found in both the healthy and dementia-affected brains.

‘Islands’ of brains cells may contain dangerous mutations, which might be common among the public, the scientists concluded.

‘Our discovery may also explain why no two cases of Alzheimer’s or Parkinson’s are the same,’ Professor Chinnery said. 

‘Errors in the DNA in different patterns of brain cells may manifest as subtly different symptoms.

‘These mutations likely form when our brain develops before birth – in other words, they are sat there waiting to cause problems when we are older.’

Further research is required to determine whether certain mutations are more common in dementia sufferers.

However, the study’s findings may help in the diagnosis and treatment of rare neurodegenerative diseases, the scientists claim.

‘Our data suggests the same genetic mechanisms could be responsible in non-inherited forms of these diseases, so these patients may benefit from the treatments being developed for the rare genetic forms,’ Professor Chinnery said.

Diseases like Alzheimer’s are thought to come about when toxic proteins build up in the brain, destroying parts of the vital organ.

This can lead to personality changes, forgetfulness and a loss of control.

Only around one in 20 sufferers has a family history of these diseases; where genes are inherited from one or both parents.

The vast majority of dementia cases were once thought to be a mystery, however, this new study suggests spontaneous mutations before birth may be to blame. 

Alzheimer’s affects around 5.5 million people in the US and 550,000 in the UK. Most sufferers live just eight-to-10 years after being diagnosed.

WHAT IS ALZHEIMER’S?

Alzheimer’s disease is a progressive, degenerative disease of the brain, in which build-up of abnormal proteins causes nerve cells to die.

This disrupts the transmitters that carry messages, and causes the brain to shrink. 

More than 5 million people suffer from the disease in the US, where it is the 6th leading cause of death.

WHAT HAPPENS?

As brain cells die, the functions they provide are lost. 

That includes memory, orientation and the ability to think and reason. 

The progress of the disease is slow and gradual. 

On average, patients live five to seven years after diagnosis, but some may live for ten to 15 years.

EARLY SYMPTOMS:

• Loss of short-term memory
• Disorientation
• Behavioral changes
• Mood swings
• Difficulties dealing with money or making a phone call 

LATER SYMPTOMS:

• Severe memory loss, forgetting close family members, familiar objects or places
• Becoming anxious and frustrated over inability to make sense of the world, leading to aggressive behavior 
• Eventually lose ability to walk
• May have problems eating 
• The majority will eventually need 24-hour care   

 Source: Alzheimer’s Association

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