Before reading this, you might want to get some cold towels to wrap round your head. I’ve got some ready for writing it.
My brain starts to struggle when I read newspaper stories that seem to show something causes dementia or increases your chance of developing dementia and then does a U-turn in the same article. Here is an example from the Independent where it says
“Delirium after undergoing surgery can triple the chances of older patients developing dementia…” Anyone would think that “can triple the chances” must mean that the delirium increases your chance of getting dementia.
But the researcher himself is quoted, five short sentences later, as saying that he does not yet know whether preventing delirium could also help prevent dementia. Anyone would now start to ask another question. How can it be that there is a thing that triples the risk, but that preventing the thing may not reduce the risk? My head hurts!
It would not be so bad if the writer said, “People who suffer from delirium are three times more likely to be discovered to have dementia later.” That would tell you that delirium is associated with increased dementia. The researcher says he can’t say if the link is causal, but the writer of the article suggests that it does.
Telling the difference between association and causation can be done like this. Santa Claus is always associated with Christmas in our house, but he does not cause Christmas. He is so closely associated that we never expect him except around Christmas, but that still does not mean he caused it. Nor did Christmas cause Santa Claus. Does that make sense? There is a difference.
We might prove one day that the stress caused by delirium does tip people into dementia who would not have got it, had the delirium been prevented. That’s always going to be hard to prove and we are not there yet. All we know so far is that they are associated.
So why is my brain overheating? Well, there are lots of ways in which older people get denied good care, and one of them might be if surgeons were refusing to operate “because of the risk of dementia caused by post-operative delirium.” To be honest, surgeons are very bold and would probably not deny treatment in many cases. But older people are more afraid of dementia than even cancer, so telling them that they are bound to get a delirium that will cause dementia would be a great way to frighten older people into taking themselves off surgical waiting lists.
So, this is a respectful plea for journalists to try to make a difference in their reporting, because of the harm it might do to real people and distress caused if the words are misleading. Don't mix up association and causation. And if you are worried about dementia risk in hospital, read Chapter 12 of Dementia the One Stop Guide.