A contagion of social symptoms

Photo by Flickr user BLW Photography. Click for sourceThere’s a fascinating study just published online by the journal Epidemiology that examines how many reports of chemical spills may in fact be ‘mass hysteria’ or ‘mass psychogenic illness‘.

Psychogenic illness is where medical problems appear; like paralysis, irritation, loss of consciousness, headaches and so on; despite there being no damage to the body or a standard cause for the symptoms.

The idea is that they are caused by ‘psychological factors’, which is a fairly woolly way of saying that we can often experience symptoms that normally appear in other disorders simply through psychological distress.

They appear in many forms, most spectacularly in what is now diagnosed as conversion disorder, where people can be, to all intents and purposes, blind or paralysed without having any damage to their eyes or nervous system.

Although these most striking presentations are uncommon, medical symptoms without a clear medical cause are actually very frequent. A study in 2000 found that 11% of consultations to neurologists involved symptoms that were “not at all explained” by medical findings while the symptoms of 19% of the patients were only “somewhat explained”.

Neurology has the benefit that, although nervous system disorders are often difficult to treat, they can be quite precisely diagnosed, so it’s unlikely that its just due to the vagueness of the medical definitions.

And if you think the figures quoted above seem weirdly high, they’re actually the lowest that have been reported. A previous study found 42% of patient with neurological symptoms did not have neurological damage that explained them.

These are usually individual cases that report to the doctor, but mass psychogenic illness is where these symptoms seems to rapidly appear in groups of people through a form of ‘social contagion’.

Previous anecdotal reports have often noted that these cases often appear as suspect ‘chemical incidents’ but where tests show no chemical was ever presented.

This new study analysed 280 medical accounts of suspected ‘chemical exposure events’ reported to the Centre for Radiation, Chemical and Environmental Hazards in the UK.

The reports were given to several independent medical toxicologists, who rated them being genuinely due to the effects of a chemical spill, or likely to be due to psychogenic illness because the symptoms didn’t match the chemical or appeared without a chemical actually being present and quickly spread between people.

For example, here’s a summary of one of the cases of ‘chemical incidents’ identified as mass psychogenic illness:

A student alleged that he had analysed the tap water from a college building and found lead levels 12 times the recommended maximum. The student complained of symptoms and reported them to his family doctor. 250 staff and students were advised not to drink the water. Some developed headaches that were attributed to lead poisoning. Testing of the water samples showed lead to be below statutory levels.

Out of the 280 incidents reported to the Health Protection Agency, 19 (about 7%) were rated as being cases of mass psychogenic illness.

Interestingly, these incidents were more likely to take place in healthcare facilities and schools, and were more likely to be triggered by an odour that wasn’t recognised as smoke.

We tend to assume that medical symptoms always have clear bodily causes, but a significant minority are likely caused by expectation and psychological stress.

Bodily symptoms are simply another way in which we can express psychological distress even if we have no idea that this is what is happening.

Link to Pubmed entry for study on mass psychogenic illnes.

2 thoughts on “A contagion of social symptoms”

  1. But this assumes that Neurology knows all, sees all. That it is a field of medicine beyond compare. When in truth, I’d like to see some studies on the limits of Neurologists, who, far more than other doctors, are mind-blind to symptoms and illnesses outside their limited jurisdiction, yet are uber-willing to Pronounce. Oh, by far.

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