Greater than 6 cups per day

Should you be worried about the amount of coffee or tea you drink?
...
...
Greater than 6 cups per day, we did see an increase in dementia risk,"
she notes.
...
...
"Looking at the US, they usually recommend less than 400 milligrams.
So overall, moderation and keeping your consumption to one to two cups
- that's what I'd recommend."

https://cosmosmagazine.com/health/body-and-mind/coffee-tea-caffeine-debunks/