There are many symptoms of being insane. One thing to note is that insanity is not a psychotic break. Psychotic breaks can be treated with medication.
Insane people are usually those with untreated mental illnesses. The disease reeks havoc on the brain. But a person with a mental illness can snap back to insanity with the right treatment. It sometimes just takes days on anti psychotics for them to begin to make sense again.
Other symptoms of insanity is the inability to function. People who are insane usually need to be monitored 24-7. They might have to live at a mental home that is under lock down. Usually nurses or aids are assigned to chart their behavior from the time they wake to the time they sleep.
The symptoms of being insane are literally a lack of ability to hold a logical conversation. People who cannot speak or do anything for themselves to help themselves (aside from having a physical impediment that prevents them from doing so) are usually considered insane.