Paranoid schizophrenia, or schizophrenia with paranoia as doctors now call it, is the most common example of this mental illness.
Schizophrenia is a kind of psychosis; your mind doesn't agree with reality. It affects how you think and behave. This can show up in different ways and at different times, even in the same person. The illness usually starts in late adolescence or young adulthood.
People with paranoid delusions are unreasonably suspicious of others. This can make it hard for them to hold...
Substance Abuse and Mental Health Services Administration
This government agency was created to focus attention, programs, and funding on improving the lives of people with or at risk for mental and substance abuse disorders. This link will take you to their web site.