Moreover, actual conclusion of the paper: “Common vaccines were not associated with a decreased risk of dementia. Unmeasured confounding and detection bias likely accounted for the observed increased risk.”
Conclusions: Common vaccines were not associated with a decreased risk of dementia. Unmeasured confounding and detection bias likely accounted for the observed increased risk.
The “attenuated” in this case means “weakened the case for”.
Or, in other words, we found a correlation without finding any causation.