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Research

Anticholinergic drugs and risk of dementia: case-control study

BMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k1315 (Published 25 April 2018) Cite this as: BMJ 2018;361:k1315

Rapid Response:

Meaning of results unclear

This is an admirable study, very thoroughly carried out, it would seem. The authors do not, however, make a clear statement of what most readers would like to know - namely, the risk of developing dementia if one is prescribed a potent anticholinergic drug versus the risk if one is not prescribed such a drug.

According to the figures supplied in the paper, 14 453 out of 100 856 people given an anticholinergic drug went on to develop dementia (14.33%) compared to 23 617 out of 223 847 who were not prescribed one of these drugs (11.76%), a crude relative risk of about 1.2. This suggests that if anticholinergic drugs do increase the risk of dementia the effect is relatively weak and also that it is, to some people, not that big a risk, since 85% of those who were given the drugs did not develop dementia. Before throwing out anticholinergic drugs altogether, should we not tell patients who might benefit from such a drug that there is a risk (a small one) and let them decide whether they wish to take that risk or not?

Competing interests: No competing interests

30 April 2018
Roger A Fisken
Retired consultant physician
None
Berkshire