Answer
The first significant supporting evidence for a biological cause of a mental disorder was the 19th century discovery that the psychotic disorder called general paresis was caused by the same bacterial microorganism that causes syphilis.
Syphilis
Syphilis is caused by bacteria “Treponema pallidum”. This bacteria cause infection when enter through broken skin of mucus membrane of genitals. It is sexually transmitted disease.
General paresis
When syphilis is untreated it lead to damaging of brain and cause a disease called general paresis in which mental activity become dysfunctional. The syphilis bacteria generally attack on brain and nervous system and begin about 10-30 years after syphilis infection.
