Many times studying medicine I've encountered this tiny little notion: one of the causes of the fall of the roman empire (at least its western side) was the neurotoxic effects of lead poisoning.
Exspecially the noble, ruling part of society used to find fancy to drink and eat with lead objects: according to this theory, the lead poisoning effects due to this habit led to severe effects on the rational leading abilities of these people (one of the effects of lead poisoning, particularly since the childhood, is a reduction of the IQ).
I want to ask those of you who are knowledgeable in this part of the roman history: how truth is there? It's actually a solid theory?
Well, (almost) Literally Everything has been blamed for the fall of the Roman Empire; the Lead Poisoning Thing is one of many. It's also iffy, as u/Talleyrayand explains in this post on the matter, also explored by u/eternalkerri in this post. For completeness, u/Talleyrayand's link re the causes of the fall has died, but we have the wonders of the Internet Archive to keep it alive.