Yes another good example is "the mad hatter" in Alice in Wonderland. Although it was made light of at the time the reason people in the trade that cured felt for hats with mercury developed neurological disorders that caused shaking and agitation was because they were exposed to mercury. Naturally, after all of this was known there were regulations created against occupational hazards in most industrialized countries. However, there are still some countries that don't have those regulations and if unknown these neurological disorders caused by toxins can indeed be confused for psychiatric but best to explain it all to a doctor and have them run tests. Then they can make a better conclusion.
What country?
Lead poisoning makes you act very weird.
For example, The Franklin Expedition Disaster in 1842.
If anyone has been exposed to any form of poison, pollutant or contaminant definitely that should be called to a doctor's attention and tests done to rule that out. Even if there aren't records you need to explain what the name of the pollutant was and where it occured and when. Bipolar is very distinct as a criteria and is psychiatric but toxins such as mercury or lead in extreme amounts can cause psychosis or mood changes as a result of brain damage (that may mitigate over time) and they can certainly do a blood test to rule that out and potentially treat it. Speak to them and explain what happenned. Also think when the mood changes first started just in case its not related and might be bipolar. They need to run a full battery of tests but a blood test is a definite start.