- Microscopic particles damage key parts of the brain in children as young as 14
- The brain’s of children living in unpolluted areas do not show any damage
- Researchers believe this may explain behavioural problems, such as violence
- Once promoted as environmentally-friendly, diesel is now linked to heart disease
- The UK is notoriously bad at air pollution, with 37 cities having illegal levels
Scientists last night said a major cause of dementia was ‘hiding in plain sight’ in exhaust fumes, being inhaled by young children and damaging their brains.
The research, by experts in the US and Mexico, showed microscopic particles had caused obvious damage to key parts of the brains of children by the age of 14.
They said this damage might explain behavioural problems including violence in adolescence, and could pave the way for the development of Alzheimer’s disease in later life.
An estimated 850,000 people in the UK currently have dementia, and the number is expected to soar to one million by 2025 and two million by 2050.
Diesel emissions linked to Alzheimer’s have been found in the brains of three-year-olds
Diesel fumes alter the structure of the heart, raising the risk of early death, a major British study found last month.
Even supposedly safe emission levels can have a significant impact, researchers discovered.
They added pedestrians should try to keep as far away from the kerb – and passing cars – as possible.
Scientists from Queen Mary University of London and Oxford University found a specific link between deformation of the heart and the fine, sooty particles emitted by diesel engines.
They found those who live in areas of high diesel air pollution are more likely to have an enlarged chamber on the left side of their heart.
If this left ventricle becomes too big the heart loses pressure and power.
This means it cannot pump as much blood, raising the risk of heart attack, heart failure and early death.
Experts are increasingly aware of the impact of diesel fumes on human health, including the risk of asthma, dementia and cancer.
The disease is thought to be largely linked to genetics – but increasing evidence suggests other factors such as smoking, obesity and lack of exercise may increase the risk.
The new study suggests air pollution may also play a role.
The UK is notoriously bad at controlling air pollution, with 37 cities British cities persistently displaying ‘illegal’ levels of air pollution – which has seen the Government repeatedly hauled into court over the last few years.
The research team examined the brains of 21 young adults and 13 children from Mexico City who had died in accidents but were otherwise healthy.
They found evidence of high levels of fine nanoparticles embedded in the structures of the brain in children as young as three years old.
The particles – known as PM2.5 – are particularly a problem in the emissions of diesel cars.
The scientists, writing last night in the Journal of Alzheimer’s Disease, said damage started to become evidence in the brains of children in their early teens.
In one child, a 14-year-old girl from south-east Mexico City, they said they found very high levels of PM2.5 in the frontal lobe of the brain – a part of the brain responsible for attention, short-term memory tasks, planning and motivation.
They wrote: ‘Abundant nanoparticles are seen in [her] luminal red blood cells, endothelial cells, and basement membranes.’
Similar damage was seen in other teenagers and the young adults, who were mostly aged in their 20s.
Particles from diesel emissions lodge in parts of the brain associated with memory (stock)
DIESEL FUMES CAUSE COUGHING AND SHORTNESS OF BREATH
Diesel fumes cause coughing and shortness of breath, a study found last month.
British scientists have physical evidence that car fumes cause nerves in the lungs to misfire.
It was known that people with asthma, taken to traffic-heavy Oxford Street in London, for example, are worse affected than those in less polluted areas.
Researchers can now explain the effect of diesel particles, which are so tiny that the body mistakes them for natural molecules and draws them deep into the lungs.
A team from Imperial College London discovered diesel fumes trigger a receptor in the airway, starting a chain reaction that causes nerves in the lungs to fire incorrectly.
Diesel particles are 83 per cent man-made carbon, but it is the chemicals on their surface that are now known to cause coughing and wheezing.
Testing diesel fumes on human lung tissue, the Imperial College team found these chemicals, known as polycyclic aromatic hydrocarbons, trigger the nerves responsible for coughing.
It starts in the airways, where the diesel fumes react with receptors, causing an electrochemical imbalance called oxidative stress.
This then opens a channel in the airway, just below the trachea, that makes nerves in the lungs misfire to cause coughing, wheezing and a painful tightening in the chest.
These respiratory reflexes, meant to protect the lungs from harmful bacteria, could make asthma worse when they are triggered incorrectly.
Children who lived in unpolluted areas had no sign of the same damage, the researchers said.
Dr Lilian Calderon-Garciduenas, of the University of Montana in the US, said car emissions are breathed in through the nose and enter the brain immediately, crossing the blood-brain barrier with ease.
‘The predominant combustion particles in young brains have properties that enable them to cause oxidative damage because these nanoparticles are capable of crossing all barriers, she said.
‘No barrier is spared.
‘In the context of serious continuous exposures to high concentrations of fine particulate matter (PM 2.5) … the issue of who is at risk of neurodegeneration at an early age should be an urgent public health concern.
‘The effects of poverty, urban violence and urban stress on impaired cognitive skills are also very important for the developing brain and can’t be ignored.’
Her team wrote: ‘Highly oxidative, combustion nanoparticles entering young developing brains – the culprit hidden in plain sight in Alzheimer’s disease development – constitute a very serious public health issue, with grave social and economic consequences.’
Diesel car controversy
Diesel cars have been promoted since the 1970s as an environmentally-friendly choice because they emit less carbon dioxide, the greenhouse gas which causes global warming.
Tony Blair’s Labour government, in particular, used generous tax breaks to persuade drivers to buy diesel cars.
The tactic – which aimed to help Britain hit EU carbon emissions targets – contributed to the number of diesel drivers in Britain jumping from around 1.5million a decade ago to about 11million today.
But in recent years scientists have realised that diesel also produces more of the tiny particles and nitrogen oxides that are damaging to human health.
Medical experts are increasingly aware of the impact of diesel on human health, including the risk of asthma and heart disease, but this is the strongest link so far to have been made between traffic exposure and dementia.
NHS watchdog NICE last year warned air pollution now contributes towards 25,000 deaths a year in England – almost 5 per cent of all deaths.
It called for a reduction in speed limits and traffic to be restricted around schools.
Separate research, published in January this year, found that people living close to main roads and exposed to traffic fumes were up to 12 per cent more likely to develop dementia.
Those researchers, from University of Toronto, calculated that among those at the highest risk – those living within 50 metres of a major road – up to one in nine cases of dementia could be caused by traffic exposure.
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