Short-term spikes in air pollution may speed up brain decline in older men – but taking ASPIRIN could protect cognition, study claims
- Peking University researchers looked at nearly 1,000 men aged 70 in Boston, US
- Found even small increases in air pollution over month sped up cognitive decline
- This was even at levels below what is usually considered dangerous by WHO
Being exposed to higher air pollution levels for a month could speed up cognitive decline in older men, a study has suggested.
Researchers found people performed poorer in recall and reaction time tests if air pollution levels increased in the 28 days before they were quizzed.
But men taking commonly prescribed anti-inflammatory drugs such as aspirin were less affected, scientists discovered.
The study, by Peking University in China, looked at a cohort of nearly 1,000 men with an average age of 70 who lived in Boston in the US.
Cognitive function was assessed using a series of tests over time to determine their memory, attention and learning.
This was compared to the average levels of fine particulate matter (PM2.5) in the air in the weeks prior to the tests.
Experts found even small increases in PM2.5 were linked to decline in cognition, a trend which is heavily associated with dementia.
This was even at levels below what is usually considered dangerous, which scientists have described as ‘startling’.
Being exposed to higher levels of air pollution for up to a month can speed up cognitive decline in older men, a study has suggested (file)
Average PM2.5 level in the study were around 10.13μg per m3, which is slightly above the World Health Organization’s recommended air quality target of 10μg per m3.
For comparison, Britain’s average PM2.5 concentration was around 10.5µg per m3 in 2019 and globally the level is 44μg per m3.
Many studies have linked repeated exposure to air pollution to a steady decline in brain function. But this is one of the first to highlight the short-term damage.
Professor Xu Gao and colleagues from Peking looked at data from 954 men during the period of 1995 to 2012.
The men had participated in repeated cognitive assessments to test their attention, learning and memory.
Levels of PM2.5 – the finest type of air pollution, mainly produced by the exhausts of cars – were recorded on the day of the cognitive assessments.
PM is a mixture of solid particles and liquid droplets found in the air.
They are created from a variety of sources including traffic, construction sites, unpaved roads, fields, smokestacks or fires.
Most particles form in the atmosphere as a result of reactions of chemicals such as sulphur dioxide and nitrogen oxides.
Some PM, such as dust, dirt, soot, or smoke, is large or dark enough to be seen with the naked eye.
Other PM is so small it can only be detected using an electron microscope.
PM2.5 – of diameters that are generally 2.5 micrometers and smaller – differ from PM10 – 10 micrometers and smaller.
Source: US EPA
People in areas where average PM2.5 levels rose to between 8.52 and 10.25 μg per m3 over the month saw the biggest drops in their cognition. It is not clear if the decline was permanent.
Researchers behind this study didn’t examine why air pollution appears to affect cognitive function, or how it can do it so quickly.
But previous studies have found it may be due to PM2.5 particles reaching the brain, triggering inflammation and damaging neurons.
The researchers also did not look at other lifestyle factors that may have influenced the findings, such as how much sleep participants had, their diet, exercise levels or alcohol consumption.
Commenting on the study, Professor Joanne Ryan and Dr Alice Owen from Monash University in Melbourne, Australia said: ‘The findings were quite startling.
‘Even relatively small increases in the levels of PM2.5 in the three to four weeks prior to testing were associated with consistently worse cognitive performance.
‘Boston, the city in which this study took place, has by no means the worst air quality in the US or the world, and yet significant detrimental effects of air pollution on cognitive function were observed.
‘While findings from the current study were specific to white male veterans with an average age of 73 years, and thus an older population who is more susceptible to cognitive decline, they are likely to be generalizable to the larger population.
‘For example, exposure to high levels of air pollution has been shown to affect brain development in children, and women appear even more susceptible to the effects of air pollution on respiratory health than men.’
Academics also wanted to learn if participants taking common anti-inflammatory medications – such as aspirin – were less prone to cognitive decline.
Results showed men using the drugs were slightly less likely to see their scores drop when pollution levels rose.
Professor Ryan and Dr Owen described the findings as ‘exciting’, adding: ‘They align with the supposed causal mechanisms underpinning the negative effects of PM2.5 on human health and support the role of inflammation in cognitive decline and dementia.
‘However, at this early stage we need to be very cautious in not over-interpreting the data.
‘There are likely to be many other differences between men who use NSAIDs [anti-inflammatory drugs] and those who don’t, and observational studies like the one by Gao et al. can’t fully tease these apart.
‘For example, the use of NSAIDs might be associated with better access to healthcare or health literacy, and these factors could not be explored in Gao’s analysis.
‘The findings provide a tantalizing possibility of better understanding the role of air pollution on cognitive health, and more research into the underlying mechanisms of NSAIDs’ potential protective effects is urgently needed.’
The study has been published in the journal Nature Aging.
WHAT HAVE RECENT STUDIES SHOWN POLLUTION CAN DO TO OUR HEALTH AND BODIES?
CAUSE CHILDREN TO HAVE A LOW IQ: Researchers at the University of California, San Francisco, found in May 2019 that children born to mothers who live in polluted areas have an IQ that is up to seven points lower than those living in places with cleaner air.
CAUSE CHILDREN TO HAVE POORER MEMORY: Researchers at the Barcelona Institute for Global Health found boys exposed to greater levels of PM2.5 in the womb performed worse on memory tests by the time they are 10.
DELAY THE DEVELOPMENT OF CHILDREN: Youngsters who live less than one-third of a mile away from busy roads are twice as likely to score lower on tests of communication skills in infancy, found researchers at Eunice Kennedy Shriver National Institute of Child Health in April. They were also more likely to have poorer hand-eye coordination.
MAKE CHILDREN MORE ANXIOUS: University of Cincinnati scientists claimed pollution may alter the structure of children’s brains to make them more anxious. Their study of 14 youngsters found rates of anxiety was higher among those exposed to greater levels of pollution.
CUT YOUR CHILD’S LIFE SHORT: Children born today will lose nearly two years of their lives because of air pollution, according to a report by the US-based Health Effects Institute and the University of British Columbia in April 2019. UNICEF called for action on the back of the study.
RAISE A CHILD’S RISK OF AUTISM: Researchers at Monash University in Australia discovered youngsters living in highly polluted parts of Shanghai have a 86 per cent greater chance of developing ASD. Lead author Dr Yuming Guo said: ‘The developing brains of young children are more vulnerable to toxic exposures in the environment.’
CAUSE ASTHMA IN CHILDREN: Four million children around the world develop asthma each year because of road traffic pollution, a major study by academics at George Washington University estimated. Experts are divided as to what causes asthma – but exposure to pollution in childhood increases the risk by damaging the lungs.
MAKE CHILDREN FAT: University of Southern California experts found last November that 10 year olds who lived in polluted areas when they were babies are, on average, 2.2lbs (1kg), heavier than those who grew up around cleaner air. Nitrogen dioxide pollution could disrupt how well children burn fat, the scientists said.
LEAVE WOMEN INFERTILE EARLIER: Scientists at the University of Modena, Italy, claimed in May 2019 that they believe pollution speeds up ageing in women, just like smoking, meaning they run out of eggs faster. This was based on them finding almost two-thirds of women who have a low ‘reserve’ of eggs regularly inhaled toxic air.
RAISE THE RISK OF A MISCARRIAGE: University of Utah scientists found in January that pregnant women are 16 per cent more likely to suffer the heartbreak of a miscarriage if they live in areas of high pollution.
RAISE THE RISK OF BREAST CANCER: Scientists at the University of Stirling found six women working at the same bridge next to a busy road in the US got breast cancer within three years of each other. There was a one in 10,000 chance the cases were a coincidence, the study said. It suggested chemicals in the traffic fumes caused the cancer by shutting down the BRCA genes, which try to stop tumours growing.
DAMAGE A MAN’S SPERM: Brazilian scientists at the University of Sao Paulo found in March that mice exposed to toxic air had lower counts and worse quality sperm compared to those who had inhaled clean air since birth.
MAKE MEN LESS LIKELY TO GET SEXUALLY AROUSED: Scientists at Guangzhou Medical University in China found rats exposed to air pollution struggled to get sexually aroused. Scientists believe it may also affect men, as inhaling poisonous particles may trigger inflammation in blood vessels and starve the genitals of oxygen – affecting men’s ability to become sexually aroused.
MAKE MEN MORE LIKELY TO HAVE ERECTILE DYSFUNCTION: Men who live on main roads are more likely to have difficulty getting an erection due to exposure to pollution, a Guangzhou University in China study suggested in February. Toxic fumes reduced blood flow to the genitals, tests on rats showed, putting them at risk of developing erectile dysfunction.
RAISE THE RISK OF PSYCHOSIS: In March, King’s College London scientists linked toxic air to intense paranoia and hearing voices in young people for the first time. They said uncovering exactly how pollution may lead to psychosis should be an ‘urgent health priority’.
MAKE YOU DEPRESSED: Massachusetts Institute of Technology researchers found in January that that the more polluted the air, the sadder we are. Their study was based on analysing social media users in China alongside the average daily PM2.5 concentration and weather data where they lived.
CAUSE DEMENTIA: Air pollution could be responsible for 60,000 cases of dementia in the UK, researchers from King’s College London and St George’s, University of London, calculated last September. Tiny pollutants breathed deep into the lungs and enter the blood stream, where they may travel into the brain and cause inflammation – a problem which may trigger dementia.
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