Switching to unleaded petrol has 'caused dementia rates to fall'

Switching to unleaded petrol ‘may be behind dementia rates falling 15% each decade in Europe and North America because lead can damage the brain’

  • University of Toronto scientists say switch to unleaded petrol played vital role 
  • They believe exposure to lead from exhausts caused dementia cases to spike
  • But since switching to unleaded several decades ago rates have fallen by 15%

Switching to unleaded petrol may be behind a decline in cases of dementia across Europe and North America, research suggests.

Ageing populations have meant more people than ever are living with the memory-robbing disorder.

But other studies have shown dementia rates have actually been falling by up to 15 per cent every decade, since the 1980s.

This date coincides with Governments switching to unleaded petrol, according to researchers from the University of Toronto.

The authors could not prove lead causes dementia – but they pointed to an array of studies that showed it can be detrimental to brain health. 

A decline in cases of dementia across Europe and North America has been sparked by a ban on lead in petrol, research suggests (stock image) 

They pointed to a form of dementia known as limbic-predominant age-related TDP-43 encephalopathy (LATE), which is similar to Alzheimer’s.

The researchers said ‘heavy metals such as lead’ had been linked to the condition, which mainly affects people over 80.

They believe the prevalence of LATE will continue to plummet as older generations, who were exposed to leaded petrol, die out.

A growing body of evidence has linked changes to behaviour and mental health to exposure to lead – a known neurotoxin that kills brain cells.

Excessive amounts seeping into the bloodstream can increase brain age by up to six years, studies have shown.

The compound was added to petrol almost a century ago to make car engines more efficient.  

As more studies revealed the dangers, it was steadily phased out from the 1970s. By 1986 unleaded petrol was on sale in the UK.

Leaded petrol was finally banned under EU law in 2000 – four years after the US did the same.

Study author Professor Esme Fuller-Thomson said: ‘While the negative impact of lead exposure on the IQ of children is well known, less attention has been paid to the cumulative effects of a lifetime of exposure on older adults’ cognition and dementia.

‘Given previous levels of lead exposure, we believe further exploration of this hypothesis is warranted. 

‘The levels of lead exposure when I was a child in 1976 were 15 times what they are today.

‘Back then, 88 per cent of us had blood lead levels above 10 micrograms per deciliter.’ 

ZhiDi Deng, a pharmacy student who co-wrote the article, said: ‘If lifetime lead exposure is found to be a major contributor to dementia, we can expect continued improvements in the incidence of dementia for many more decades as each succeeding generation has fewer years of exposure to the neurotoxin.’ 

The researchers note that other plausible explanations for the improving trends in incidence include better education, less smoking and healthier blood pressure levels compared to previous generations. 

In the UK there are about 850,000 people with dementia, a figure expected to rise to two million by 2050 as the population ages. 

Roughly 5.8million Americans have the disorder. Currently, drugs can only treat the symptoms, and not the cause. 

The study published in the Journal of Alzheimer’s Disease.



Dementia is an umbrella term used to describe a range of progressive neurological disorders, that is, conditions affecting the brain.

There are many different types of dementia, of which Alzheimer’s disease is the most common.

Some people may have a combination of types of dementia. 

Dementia is a global concern but it is most often seen in wealthier countries, where people are likely to live into very old age.


The Alzheimer’s Society reports there are more than 850,000 people living with dementia in the UK today, of which more than 500,000 have Alzheimer’s.

It is estimated that the number of people living with dementia in the UK by 2025 will rise to over 1 million. 

As a person’s age increases, so does the risk of them developing dementia.

Rates of diagnosis are improving but many people with dementia are thought to still be undiagnosed.


Currently there is no cure for dementia.

But new drugs can slow down its progression and the earlier it is spotted the more effective treatments are.

Source: Alzheimer’s Society 

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