One thing we have learnt this week – dementia and pollution

2014-06-28 11.42.29Is there a link between dementia and pollution?  A new study in Canada has suggested that people who live near main roads are more likely to suffer dementia.  For those living within 50m of a main road its a 7% increase in risk.  The risk drops off very steeply with distance.  Of course correlation is not the same as causation and dementia is a complex condition with a number of causes and as they put it on the news last night the chief risk factor is age.

This blog has covered other pollution health stories before.  One was the extraordinary theory the developed world’s postwar crime wave was caused by lead in petrol.  Although that paper was said be convincing there was one huge flaw in its argument I could see.  That was, the drop in crime that has occurred started immediately as the lead was removed from petrol.  Since lead in the body cannot be removed (that’s part of its problem) it seems unlikely lead was the cause.  However this study on dementia and pollution does need to be taken seriously.  For starters the team looked at the health of everyone on Ontario for over a decade.  This was 6.6 million people.  The drop with distance also matches what we know about particulate pollution which is levels fall off with distance very rapidly.  From the biological perspective we know particulates contain microscopic quantities of transition metals such as iron and copper.  These react with hydrogen peroxide which is produced as a by product of respiration forming free radicals which damage almost all molecules in the body they come in contact with.  Free radical and metals have been implicated as a cause of Alzheimers disease.

Particulates have been cited as one of the causes of a host of diseases, these include strokes, heart disease and asthma.  Surely it is time for a more radical look at transport?  To move much more to cycling and walking.  This is one problem that electric cars cannot totally solve since according to George Monbiot up to 50% of a car’s pollution is not due to what comes out of the exhaust but other interactions such as the tyres with the road.

In the meanwhile on thing that is said to help dementia is walking and cycling so get going!  Happy new year.


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