Exposure to air pollution increases people's risk of Alzheimer's disease and suicide, new research suggests.
Lifelong exposure to fine-air particles raises people's levels of the 'Alzheimer's protein' APOE4, which is associated with rapid-onset dementia, as well as making people up to 4.92 times more likely to take their own lives, a study found.
The researchers believe fine-air particles enter people's brains when they breathe before travelling elsewhere in their bodies via their bloodstreams.
Past research suggests such particles, which weigh less than 0.0025mg and are given out in vehicle-exhaust fumes, cause inflammation.
Inflammation has previously been linked to both Alzheimer's and mental-health problems.
The study was carried out in Mexico City, which is home to 24 million people who are exposed to fine-air particle concentrations above US Environmental Protection Agency standards every day.
Alzheimer's disease affects around 5.5 million people in the US and 850,000 in the UK.
ACTION USELESS DECADES LATER
Lead author Dr Lilian Calderón-Garcidueñas, from the University of Montana, said: "Alzheimer's disease hallmarks start in childhood in polluted environments and we must implement effective preventative measures early, including the prenatal period and childhood.
"It is useless to take reactive actions decades later. Defining pediatric environmental, nutritional, metabolic and genetic risk-factor interactions are key to preventing Alzheimer's disease."
Results further suggest air pollution also increases levels of the abnormal proteins hyperphosphorylated tau and beta amyloid, which have both previously been associated with Alzheimer's.
HOW RESEARCH WAS CARRIED OUT
The researchers analysed 203 autopsies of people who died at between 11 months and 40 years old.
It is unclear what caused their deaths.
The researchers assessed the autopsies' levels of proteins that are associated with Alzheimer's.
The findings were published in the journal of Environmental Research.
BEETROOTS COULD HELP
This comes after research released last month suggested beetroots could help in the fight against Alzheimer's.
Betanin, which is a compound that gives the vegetable its distinctive red colour, may slow the accumulation of protein plaque tangles, which are associated with the condition, in the brain.
Study author Dr Li-June Ming, from the University of South Florida, said: 'Our data suggest that betanin, a compound in beet extract, shows some promise as an inhibitor of certain chemical reactions in the brain that are involved in the progression of Alzheimer's disease.
'This is just a first step, but we hope that our findings will encourage other scientists to look for structures similar to betanin that could be used to synthesise drugs that could make life a bit easier for those who suffer from this disease.'
If you are having suicidal thoughts, contact the Samaritans here.