Doctors and health experts in India have called on the country to introduce policies to deal with air pollution that they believe is a key factor in accelerating the onset of Alzheimer’s disease.
Alzheimer’s, the most common type of dementia, is a progressive disease that can cause patients to lose the ability to recognise their surroundings, according to the US Centres for Disease Control and Prevention. The disease can eventually lead to death.
There are more than 55 million people with dementia worldwide, at least 60 per cent of whom live in low and middle-income countries, the World Health Organisation says.
Nearly 10 million new cases a year are reported, the WHO estimates.
On World Alzheimer’s Day observed on September 21 for a month, Alzheimer’s Disease International (ADI), a non-profit international federation of Alzheimer’s and dementia associations from around the world, released its report Reducing dementia risk: never too early, never too late on Wednesday.
It draws on insights from about 90 researchers, healthcare professionals, policymakers, people living with dementia and informal carers.
It says that while research shows people can develop dementia for decades before symptoms become apparent, reducing exposure to risk factors can delay, slow or even prevent projected dementia cases.
“Research increasingly shows that dementia can be delayed or even prevented by targeting our lifestyle choices such as exercise, diet, and social connections; also, it is never too late to correct hearing loss,” says Louise Robinson, professor of primary care and ageing at Newcastle University and co-chairwoman of ADI’s medical and scientific advisory panel.
Referring to a study by The Lancet, the report says inactivity, excessive alcohol consumption, obesity, hypertension, diabetes, depression and hearing impairment are some of the factors linked to the condition.
But one of the key points it highlights is air pollution, which is linked to a higher risk of dementia.
The report says the danger comes from fine particulate matter known as PM 2.5 – the finest dust and other harmful particles measuring less than 2.5 microns that penetrate deep into the lungs and enter the bloodstream, leading to respiratory and cardiac diseases.
Prof Roxana Carare of the University of Southampton, who sits on the British government’s committee on the medical effects of air pollutants, told the ADI the idea that the particles enter the brain directly is far less likely than the cardiovascular route.
She said the soluble elements of the particles enter the bloodstream and affect the walls of blood vessels, making them less efficient in fulfilling their function of clearing the brain of waste – such as amyloid plaques, essentially malformed proteins in the brain that accumulate with age.
“That would explain why air pollution is linked both to Alzheimer’s and to vascular dementia,” Prof Carare said.
The report is particularly concerning for Indians, as the country of 1.4 billion has 39 of the world's 50 most polluted cities, according to the Swiss firm IQAir in its World Air Quality Report released in March.
New Delhi is the most polluted capital city in the world where the pollution levels continue to hover over safe limits.
The city’s PM 2.5 levels were at an average of 99.71 micrograms per cubic metre last year. The WHO considers five micrograms per cubic metre as the safe level of exposure to particulate pollution.
More than 3.8 million people are living with dementia in India, with this expected to rise above 11.4 million by 2050, a concerning increase of 197 per cent, the ADI said.
“Pollution is a risk factor as a day of pollution is equivalent to smoking more than 20 cigarettes a day and reduced oxygenation in brain … the exposure to pollution has been associated with higher risk of developing dementia in various peer-reviewed scientific research studies," Dr Manjari Tripathi, professor of neurology at Delhi's All India Institute of Medical Sciences, told The National.
Those views were echoed by Dr Hamed Al Sinawi, who is a consultant psychiatrist specialising in ageing and the chairman of the Alzheimer’s Society.
“According to recent studies, people living in areas with high levels of a certain kind of air pollution have a greater risk of dementia,” he told The National.
Experts blame a lack of policy in dealing with pollution as a challenge in controlling the risk of the condition.
Meera Pattabiraman, chairwoman of ADI in India, urged the government to focus on policy-making to prevent case numbers from rising “astronomically”.
“Our government doesn’t have a plan and policy for dementia. The way to look at it is to reduce the risk of dementia, which is critical for us considering the population and the most polluted country,” Ms Pattabiraman said.
“We need to handle the situation of environment pollution so the air is better and the future generation doesn’t get dementia.
"If we don’t tackle the pollution now, our numbers will go haywire. While other factors are related to lifestyle, we cannot do anything about pollution individually. The government has a bigger role to play."