If your friend Leo is displaying concerning behaviors such as paranoia, significant changes in personality, and talking to himself, it's crucial that he seeks professional help from a qualified mental health professional. Only a licensed psychiatrist or psychologist can accurately assess his condition and provide an appropriate diagnosis.
There are various mental health conditions that could potentially present with similar symptoms, including paranoid schizophrenia, but it's important not to jump to conclusions without a proper evaluation. Early intervention and proper treatment can significantly improve the outcome for individuals experiencing mental health challenges.
If you are concerned about your friend's well-being, encourage him to reach out to a mental health professional or, if you believe he is in immediate danger, consider involving a trusted adult, family member, or contacting emergency services. Always prioritize seeking professional help when dealing with mental health concerns.