Bitter Brew: High Coffee Consumption Is Associated with Smaller Brain Volume (scitechdaily.com)

Six cups a day is their limit. For 53% increase in Dementia risk

In the largest study of its kind, researchers have found that high coffee consumption is associated with smaller total brain volumes and an increased risk of dementia.

https://www.indigocard.org/

Thankfully, in addition to increasing dementia risk by 53%, it also lowers it by 65%: https://pubmed.ncbi.nlm.nih.gov/20182054/ So there is that.