The study in Wales and a second study in the US were about herpes zoster (shingles), they both seem to support a link to Alzheimer's and, from what I read, the second study mentions other dementias.

https://alz-journals.onlinelibrary.wiley.com/doi/full/10.100...

https://www.nature.com/articles/s41591-024-03201-5

and indeed the all causes dementia rate in the study does not go to zero among the vaccinated