Reacción a "Reactions: Hearing aid use reduces risk of dementia in hearing-impaired people"

The numbers are impressive and have allowed authors to assess multiple factors that might affect dementia risk apart from hearing loss. But this observational study needs to be interpreted with caution. The best quality data on the relationship between hearing loss and dementia were the studies included in a model developed by the Lancet Commission based on hearing tests (audiograms) and follow up of the patients to see if they developed dementia. The UK biobank data do not include hearing tests:  the hearing data are based on self-report which is not reliable. Hearing aid effects are difficult to interpret for two reasons:

1. people who have hearing aids often tend not to use them (although that would work against the effect of hearing-aid use shown here);
2. it is difficult to be certain if association of not using hearing aids reflects dementia causing lower hearing aid use as opposed to the reverse.

So, the suggested effect is interesting but we really need are prospective studies of hearing aid use that measure deafness like the Lancet Commission studies and carefully evaluate device use and incident dementia. There is a large multisite US study funded by NIH currently doing just that.