"Because of who her brother was, she was paranoid that she would also be called a liar."
"After spying on the Russians, he was constantly paranoid that he was being followed."
Paranoia involves intense anxious or fearful feelings and thoughts often related to persecution, threat, or conspiracy.
Paranoia can become delusions, when irrational thoughts and beliefs become so fixed that nothing (including contrary evidence) can convince a person that what they think or feel is not true. When a person has paranoia or delusions, but no other symptoms (like hearing or seeing things that aren't there), they might have what is called a delusional disorder. Because only thoughts are impacted, a person with delusional disorder can usually work and function in everyday life, however, their lives may be limited and isolated.