Erotomania may be a symptom of a psychiatric illness, including schizophrenia, schizo-affective disorder, major depressive disorder with psychotic features, bipolar disorder, or Alzheimer's disease. Erotomania is a type of delusional disorder. Other types include delusions of persecution, grandiosity, or jealousy.
Morgellons disease is a delusional disorder that leads to the belief that one has parasites or foreign material moving in, or coming out of, the skin. Morgellons disease is a little-known disorder that is often associated with nonspecific skin, nerve, and psychiatric symptoms.
Delusional disorder, previously called paranoid disorder, is a type of serious mental illness called a "psychosis" in which a person cannot tell what is real from what is imagined. The main feature of this disorder is the presence of delusions, unshakable beliefs in something untrue or not based on reality.