Final answer:
The earliest treatments for mental disorder included exorcism and trephination, which were based on the belief that evil spirits caused mental illness, and these methods varied across cultures.
Step-by-step explanation:
The earliest treatments for mental disorder can be traced back to practices such as exorcism and trephination. Trephination, which involves making a hole in the skull, was believed to allow evil spirits to leave the body, thereby curing mental illness among other disorders. Exorcism, on the other hand, was the practice used to remove the presence of adverse spirits believed to be the cause of affliction. Rites of affliction such as witchcraft and sorcery were also applied to identify the sources of mental disturbances and were widely varied depending on cultural practices. Such methods reflect the historical understanding of mental health and the evolution of psychiatric treatments over time.