This chapter will be divided into three sections: (a) an introduction to the delusional disorders; (b) a concise description of the derivation of current concepts regarding delusional disorders; and (c) some notes on phenomena associated with delusions.

An introduction to the delusional disorders

Delusional disorder is an accepted diagnosis nowadays but many aspects of its description still stem from writings of the late nineteenth and early twentieth centuries, and modern descriptions are still only a few years old.

In writing about paranoia/delusional disorder (these terms will be discussed in detail later) there are two misconceptions which must be countered. The first is that it is rare. Certainly, cases do not appear in profusion in the average psychiatrist's office but, as will be shown in Chapters 2 and 3, there are many references to different manifestations of the illness in several literatures, of which the psychiatric is but one. Cumulatively, these create an impression of a disorder that is far from unusual. In addition, because many cases remain unrecognized in the community (see p.51) it is possible that delusional disorder in its various degrees of severity is really quite common. But this is guesswork and all that we are justified in saying at present is that it is not nearly so rare as psychiatrists believe and that, rather oddly, psychiatrists are often the last professional people to see such cases.

The second misconception is that the illness is untreatable.