Throughout time there have been accounts of people that deviate from social norms with their behaviours and thoughts. But in prehistoric times, these issues were not thought to be due to mental illness. Instead, they were attributed to demonic possession. One source of evidence we have for this is trepanned skills that date back to the stone ages.
Trepanning is a form of surgery whereby an individual’s skull will be drilled into while they are alive in order to release evil spirits from within the skulls. Skulls were also trepanned after death in order to create amulets to defend others from spirit possession. However, there is little evidence to suggest trepanning cured those with mental illness.
There are some communities today that still believe spirits or demons can infest the body to cause mental illness. Norbeck (1961) found a community in rural japan for that believe spirits wander the world looking for a human host and these spirits are capable of entering bodies and causing illness until a ceremony is held to release them.