All psychiatrists will have encountered patients who present only with delusions. Most — after seeing some such patients who are obviously psychotic with persecutory and referential delusions but no other symptoms; others who seem only to have an isolated over-reaction to some perceived injustice; and yet others who are suffering not from imagined persecution but whose beliefs revolve around infidelity, illness or deformity — will have concluded that such patients frustrate all attempts at classification. Some, especially those of us who trained in the past 20 years, will recall consulting the articles by Munro, one of the very few authors who seemed prepared to grasp the nosological nettle of paranoia. He introduced the term monosymptomatic hypochondriacal psychosis. His sustained advocacy played an important part in the renaissance of paranoia as a delusional disorder in the 1980s. He was single-handedly responsible for popularising treatment with pimozide, which, as he notes, now tends to be the most widely used drug in different forms of the disorder.

In this book Munro takes on the whole field of paranoid disorders, not only delusional disorder, but also paraphrenia, standard and late varieties, delusional misidentification syndrome and folie à deux. he also reviews disorders which regularly feature in the differential diagnosis of delusional disorder, including reactive psychosis, cycloid psychosis, and paranoid, schizoid and schizotypal disorders. There is a chapter on treatment and many case descriptions.

The section of the book devoted to paranoia/delusional disorder leads off with monosymptomatic hypochondriacal psychosis (now renamed delusional disorder, somatic subtype), a subcategory whose existence Kraepelin was doubtful about, but which has dominated and shaped Munro's thinking. The approach taken with this and the other subtypes is one which will be familiar to those who have read the author's previous publications: lucid description, clear-headed analysis, a solid grasp of the complex background of ‘normal’ hypochondriasis, jealously, etc., and yet an unsatisfying feeling that the really difficult issues have been glossed over. He uses terms like ‘belief’ and ‘conviction’ liberally, but the reader is sometimes hard put to see what makes him decide some convictions are delusional, whereas others are not. Thus, a case of AIDS hypochondriasis is delusional disorder, somatic type, but a superficially similar case where there is a dysmorphic belief is not. The presence or otherwise of referential delusions — which Kraepelin came to the conclusion were present in all cases of paranoia — is hardly touched on. Everything is complicated by use of response to neuroleptic drug treatment as a validator of the diagnosis.

The second major theme of the book concerns paraphrenia, where Munro nails his colours to the mast at the outset: like paranoia, it should be separated from schizophrenia and resurrected as a separate category of illness. Here, however, the ground is very slippery. Because of the lack of studies, he leans heavily on clinical authority, some of which unfortunately turns out merely to be the pontifications of old American analysts (and worse, old eclectic British psychiatrists) writing in textbooks of the 1960s and 1970s. He has to consider whether there are differences between late-onset schizophrenia and late paraphrenia — a case of hair-splitting if ever there was one. He even ends up invoking the concept of the paranoia spectrum which he regards with veneration, but which this reviewer at least feels should have been taken round the back and shot a long time ago. Ultimately, even British psychiatrists, who have a soft spot for paraphrenia, will probably fail to be convinced by his case. Leaving aside these points of contention, which might legitimately be regarded as merely the kind of tedious and ultimately futile disputes that the topic of paranoia always generates, this is a valuable account of an area of psychiatry in which the patients are in steady supply. It is clearly and unusually well-written and makes an easy, even enjoyable read, something that cannot be said for most psychiatric text-books. At the end of the day, the reader may agree to disagree with Munro's conclusions about paranoia, but will certainly go away with a deeper appreciation of the questions it raises.