Pollution and Alzheimer’s study is garbage
The Observer article reporting Professor Pritchard’s results, mentioned by John D Hall, is extremely useful in illustrating a number of problems.
Technically, it’s a classic case of Mill’s Canons at their crudest – if two sets of circumstance differ and only one factor has changed, then the reasoning is that that factor must be the cause of the differences. In this case an observation of increased brain diseases is associated simply with the passage of time and supposedly the only thing that has changed is that these people are exposed to more pollution. But the problem with Mill’s Canons is that you can almost never say that only one thing has changed, and there is so much room for bias and subjectivity in allocating causation to a particular factor.
There are literally an infinite number of potential causes. Increased miscarriage in people living close to roads might be caused by associated economic factors.
Remember the association between the contraceptive pill and cervical cancer? But the pill itself didn’t cause cervical cancer at all, and considerable damage was done until the real causes were identified.
The empirical observations of increased rates of morbidity due to brain diseases may be fine, but there is not a shred – *none whatsoever* – that this is caused by atmospheric or other pollution. The authors present no data on changes in atmospheric or other pollution and have not even measured it or looked at the work of others on real exposures. It can say precisely nothing about what the causes are – even if they can usefully rule some out. They have simply observed a change.
For my sins I referee papers occasionally for academic journals and I have no idea how such conclusions got through. To be blunt, it is absolute garbage. There really must be a problem with our brains these days if we can get these conclusions from this data. Alarm bells should ring immediately when they are measuring differing rates of morbidity from such a wide variety of diseases as Alzheimer’s, Parkinson’s and motor neurone disease and ascribing them to one change. These diseases show completely different symptoms and effects in the brain, about the only thing they have in common is the affected organ.
It is also inexplicable in their framework that the increased rates are not observed in Japan, which is more industrialised and urbanised than many of the other nations such as Canada, Spain or Australia in the study group. As far as atmospheric pollution goes, Japan is almost identical to the UK, at least in their averages, which is what I have to hand. The changes they observe are more suggestive of social/cultural developments and differences bringing about differences in morbidity.
But the most useful thing about the paper and subsequent Observer report is what the cause selected for these changes tells us about the authors and reporters. Not actually a single cause but a whole related system of them – atmospheric pollution, industrial effluent, domestic waste, food etc. In short it is ‘modern life’ that these authors conclude is the only possible cause. The motive for selecting this cause over another has nothing to do with evidence since they have none, and so it can only be informed by their own prejudices. It is the contemporary dissatisfaction with modernity and the collapse in belief in progress – social or technical – as a real benefit that makes scientists and lay people alike suspicious of change. ‘It really scared me’, as one of the authors put it – but the conditions for his fear existed before he started the work.
In one sense they may be right to blame contemporary society – working the brain and getting it to do new things is known to alleviate many problems of senility. Maybe sitting at home being disillusioned with the outside world, with all the pollution ‘out there’, and then more ‘in here’, with your elected leaders trying to poison you, turning in on one’s own fears of doom, and with your horizons continually diminishing – that really would make your brain rot and bring you to an early end.
Paul Wight, UK
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