Final answer:
The connection between untreated syphilis and psychiatric symptoms, such as psychotic behavior, was recognized in historical medical studies, including the 1928 Norwegian study. The Tuskegee Syphilis Study infamously failed to provide effective treatment with penicillin to African American men, highlighting the medical consequences of untreated syphilis.
Step-by-step explanation:
The reason for recognizing that someone had syphilis when they were exhibiting psychotic behavior stems from medical history. In the past, neurological damage caused by untreated syphilis was noted, particularly predisposing individuals to psychiatric symptoms which could include psychosis.
This was further outlined in the Norwegian retrospective study on Caucasian men with untreated syphilis in 1928, where such damage was observed. The unethical Tuskegee Syphilis Study, which commenced in the 1930s and continued until 1972, demonstrated the severe impacts of untreated syphilis on African American men who were not given treatment despite the availability of penicillin, an effective cure that came into widespread use in the early 1940s.