Persistent Delusional Symptoms and Disorders
Alistair Munro
Introduction
Delusional disorder (DSM-IV 297.1 and ICD-10 F22)(1,2) is a psychotic illness with some superficial resemblances to schizophrenia from which, however, it is quite distinct. It presents with a stable and well-defined delusional system, which is typically ‘encapsulated’ within a personality, which retains many normal aspects, unlike the situation in schizophrenia in which there is widespread personality disorganization in addition to the psychotic features. Nevertheless, although many normal aspects of the personality are preserved, the individual’s way of life becomes progressively distorted by the intensity and intrusiveness of the delusional beliefs. Hallucinations may be present but are not usually prominent. This is a chronic disorder, probably lifelong in most instances, which retains an unjustified reputation for being untreatable. Because of the nature of their delusions, many patients are unwilling to accept that they have a mental disorder or that they require psychiatric treatment but, if they can be persuaded to cooperate and accept appropriate medication, the condition can be shown to respond to treatment in a remarkably high proportion of cases.
Delusional disorder used to be known as ‘paranoia’, and the terms are virtually synonymous. Paranoia and its related disorders were regarded as an important group of psychiatric illnesses until the early part of the twentieth century. Then, because of changing diagnostic and classificatory approaches, especially a tendency to overdiagnose schizophrenia, the diagnosis of paranoia all but disappeared from standard classificatory systems. In 1987, paranoia was again officially recognized by DSM-IIIR but was renamed delusional (paranoid) disorder—since simplified to delusional disorder. It is the only officially acknowledged member of the old group of paranoid illnesses appearing in DSM-IV and ICD-10.
Although the diagnosis of paranoia all but ceased for many years, the illness and its sufferers did not disappear. When the phenomena of the disorder came to attention the patient was either labelled as schizophrenic or else a specific feature of the delusional phenomenology was seized upon and spurious diagnoses were described. Thus we have a multiplicity of apparently disparate diagnoses such as de Clérambault’s syndrome (delusional erotomania), the Othello syndrome (delusional jealousy), querulant paranoia (a form of persecutory delusional disorder), monosymptomatic hypochondriacal psychosis (delusional disorder with somatic preoccupations), and many others. The result has been an extraordinarily scattered literature with cases recorded in a variety of medical and non-medical sources, but very few in psychiatric journals until recently. Since DSM-IIIR there has been a serious attempt to resolve the confusion and to diagnose paranoia/delusional disorder by its own intrinsic features, but many problems still bedevil the nomenclature.
Jaspers, in discussing paranoia, said: ‘Why are the paranoics as defined by Kraepelin so rare, yet when they do occur they are so typical?’ This remains true because there are striking similarities from case to case and the illness’ features clearly distinguish it from other psychoses, yet many psychiatrists continue to label it erroneously.
DSM-IV and ICD-10 provide criteria to differentiate delusional disorder as an illness sui generis and these are now widely accepted. This section adopts that official approach but with two caveats. The first is that the descriptions are bald and not very helpful to the clinician who has not actually seen cases of the disorder. The second is that the category of delusional disorder (persistent delusional disorders in ICD-10) may well be overrestrictive as it stands. However, some well-respected authorities take a somewhat different approach, regarding ‘delusional disorders’ as all psychiatric illnesses with delusions and then subcategorizing according to the underlying syndrome, which might be severe mood disorder, schizophrenia, actual delusional disorder, etc. Therefore the reader of any text must be aware of a particular author’s criteria for diagnosis in this area.
Emil Kraepelin (1856-1926) clearly described paranoia and included it in a continuum of illnesses with delusional features, especially paraphrenia and paranoid schizophrenia. This so-called ‘paranoid spectrum’ will be briefly alluded to later. Paranoid schizophrenia continues to be a widely used diagnosis but usually in the context of schizophrenia. Paraphrenia is not officially acknowledged in DSM-IV or ICD-10 but cases fitting its traditional description are quite commonly seen in practice. The present author regards it as a significant entity and the reader is encouraged to become familiar with descriptions to be found elsewhere.
At present, ‘delusional disorder’ is both an illness category and essentially the only syndrome contained within that category. In recent years, another diagnosis—delusional misidentification syndrome (DMIS)—has come into increasing prominence. Originally described in 1923 by Capgras and Reboul-Lachaux(3) as
an illness in which the individual is delusionally convinced that someone familiar in the environment has been replaced by an almost exact double, this ‘Capgras syndrome’ led a rather marginal existence in the literature for many years. Lately, however, there have been considerably more case-reports of better quality and clinical subtypes have been established. Most importantly, sound psychological and neuropathological work has increasingly shown significant cerebral pathologies in a high proportion of sufferers.
an illness in which the individual is delusionally convinced that someone familiar in the environment has been replaced by an almost exact double, this ‘Capgras syndrome’ led a rather marginal existence in the literature for many years. Lately, however, there have been considerably more case-reports of better quality and clinical subtypes have been established. Most importantly, sound psychological and neuropathological work has increasingly shown significant cerebral pathologies in a high proportion of sufferers.
DMIS is not currently recognized by DSM or ICD but in many respects it resembles delusional disorder and should certainly be included in an expanded category of that disorder.
Finally, there is an important phenomenon which is found in association with all illnesses with delusions, especially delusional disorder. This is named ‘shared psychotic disorder’ in DSM-IV and ‘induced delusional disorder’ in ICD-10, but is often still referred to by its long-established name folie à deux. Here, the primary patient has a bona fide delusional illness and a secondary patient has come to accept the delusional beliefs as true. The secondary patient is usually a highly impressionable individual living in prolonged close contact with the other; he or she is not truly deluded, but retains the beliefs tenaciously as long as the intimate relationship is maintained. A less common variety is when two people each have genuine delusional disorders and, through close proximity, come to share identical abnormal beliefs. Folie à deux is not uncommon and, as will be explained later, there are very practical reasons why the clinician should be aware of its possible presence and the ways in which it may influence management of the case.
The paranoid spectrum(4)
Since Kraepelin’s time there has been a tacit acceptance by many psychiatrists of a spectrum simplified as:
delusional disorder—paraphrenia—paranoid schizophrenia.
Somewhat anecdotally, the literature suggests that approximately 10 per cent of cases of delusional disorder or paraphrenia will deteriorate to schizophrenia though, in general, most cases of delusional disorder remain diagnostically stable in the long term. Several reports have indicated that, as one moves to the delusional disorder end, a family history of schizophrenia becomes progressively less common. The risk for schizophrenia in the close family of a case of delusional disorder appears to be much the same as in the general public. In paranoid schizophrenia the family history of schizophrenia is approximately half as common as in other schizophrenias and profound disintegration of personality is less frequent.
When dealing with cases in this general area the clinician should bear in mind the concept of a paranoid spectrum. This, plus knowledge of constituent illnesses, will make it easier to distinguish delusional disorder from superficially similar conditions, a matter of considerable importance when considering treatment and prognosis.
Problems of nomenclature
Although English-speaking psychiatrists (and most members of the public) use the word ‘paranoid’ to mean ‘persecutory’, strictly speaking it just means ‘delusional’. In many writings on ‘paranoia’ and ‘paranoid’ disorders, authors do not make it clear whether delusions are present or not in their cases.
Unfortunately, with the passage of time, the term ‘paranoid’ has come to be used so loosely that it has lost any meaningful clinical connotation. Paranoia should now be regarded as an historical usage, pretty well synonymous with delusional disorder.
The word ‘paranoid’ is still used in the official diagnoses of paranoid schizophrenia and paranoid personality disorder. The former is acceptable because the illness has delusions as a prominent feature, but it is quite illogical in describing a personality disorder, which cannot have delusions. Since it is unlikely that the personality disorder will be renamed soon, the reader should be aware of such pitfalls in our psychiatric terminology and consequently the need for ultra-careful case-descriptions.
Although the form of delusional disorder is remarkably characteristic, the delusional contents and the ways in which cases come to attention are extremely varied, and this has led to an extraordinarily complex history. The core description, that of paranoia, gradually crystallized in the latter half of the nineteenth century and was definitively delineated by Kraepelin, who recognized subtypes with delusional contents of grandiosity, persecution, erotomania, and jealousy, and also allowed for the possibility of a hypochondriacal content. He clearly differentiated paranoia from dementia praecox (i.e. schizophrenia). Kraepelin later doubted whether hallucinations could be present: in fact, non-prominent hallucinations are now acceptable and in every other respect Kraepelin’s century-old definition of paranoia still largely serves to describe present-day delusional disorder.(5)
Subsequently, Kraepelin(5) introduced the concept of paraphrenia, an illness similar to paranoid schizophrenia but with significantly better preservation of affect and of personality. As already mentioned, he regarded paranoia, paraphrenia, and paranoid schizophrenia as a relatively discrete group of illnesses, later referred to as the paranoid spectrum.
It was later found that a minority of cases of paranoia and paraphrenia eventually deteriorated to schizophrenia and this somewhat illogically led to these diagnoses being progressively ignored. Despite this, speculation on the nature of delusions continued, most notably by Jaspers (1883-1969),(6) Kretschmer (1888-1964),(7) and Freud (1856-1939) and his followers. These speculations contributed a good deal to the descriptive phenomenology of delusions but whereas we know a good deal about delusional contents, we understand little about the origin of delusions or of delusional illnesses, or the reasons for their unique features.(8) Unfortunately, as much of the writing on delusions appeared when most psychoses, and certainly paranoia, had no effective treatments, writers usually dwelt on the untreatability of paranoia, a pessimistic view that persists but is no longer warranted.
From the 1970s onwards, interest in paranoia reappeared and a more optimistic view of treatment emerged. Since its renaissance as delusional disorder in DSM-IIIR in 1987, paranoia has again become a respectable diagnosis. Not only that, it has subsumed several quasi-disorders which were undoubtedly delusional but which had been described superficially on the strength of their delusional content alone. Several of these have already been noted (see p. 281).
Nowadays the clinical description of delusional disorder is well established, but adequate case series are rare and scientific investigations are in their infancy, except in the case of the diagnosis which still remains officially unrecognized, delusional misidentification syndrome, in which underlying brain abnormalities are
commonly demonstrable. The separateness of delusional disorder from schizophrenia is beyond doubt, but its relationship to the other constituents of the paranoid spectrum still has to be determined. Delusional disorder is no longer regarded as rare, but many years of neglect have left many psychiatrists sadly unaware of its characteristic features.
commonly demonstrable. The separateness of delusional disorder from schizophrenia is beyond doubt, but its relationship to the other constituents of the paranoid spectrum still has to be determined. Delusional disorder is no longer regarded as rare, but many years of neglect have left many psychiatrists sadly unaware of its characteristic features.
Delusions: clinical aspects
A delusion may be defined very loosely as a mistaken idea which is held unshakably by the patient and which cannot be corrected. As will be seen, this is not a satisfactory definition, although it may be a useful starting point for clinical recognition of a delusional process. This brief exposition is concerned to facilitate clinical recognition and not to dwell on psychopathological theories, which are dealt with in detail elsewhere in this book.
It is a widely held opinion that delusions are qualitatively different from normal ideas or beliefs and have an all-or-nothing aspect. The DSM-IV definition initially seems to accept this viewpoint, stating that a delusion is ‘A false belief based on an incorrect inference about external reality that is firmly sustained despite what almost everyone else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary. The belief is not one ordinarily accepted by other members of the person’s culture or subculture’. But the definition goes on to say that it is often difficult to distinguish between a delusion and an overvalued idea (in which there is an unreasonable belief or idea but not held with such pathological certitude as in a delusion), and that ‘Delusional conviction occurs on a continuum’ from normal to abnormal. These two statements markedly lessen the initial description of the absolute nature of the delusional wrongness.
The definition of delusion by Mullen(9) based on the earlier description by Jaspers is widely quoted and its implications are largely accepted by DSM-IV and ICD-10. He characterizes delusions as follows:
1 They are held with absolute conviction.
2 The individual experiences the delusional belief as self-evident and regards it as of great personal significance.
3 The delusion cannot be changed by an appeal to reason or by contrary experience.
4 The content of delusions is unlikely and often fantastic.
5 The false belief is not shared by others from a similar socioeconomic group.
Clinicians widely employ the terminology on delusions introduced by Jaspers, for example when they use terms such as ‘primary’ and ‘secondary’ delusions, ‘delusional mood’ (Wahnstimmung), and ‘delusional memory’. These concepts are of some descriptive and possibly heuristic value, but they do not prove particularly helpful in distinguishing delusions from overvalued ideas in individual cases, nor in deciding whether a particular delusional phenomenon is specific to a given mental disorder.
In a sense, all delusions are secondary in that they are the product of a pathological process in the brain which, in most cases, we can only guess at. It is sometimes useful to differentiate clinically between the ‘primary’ or ‘autochthonous’ delusion, which appears fully fledged and relatively suddenly, and the ‘secondary’ delusion, which is a further development within the delusional system and may sometimes seem to be the individual’s way of rationalizing his delusional beliefs although, of course, the rationalization must necessarily be filtered through a mind already thought-disordered and affected by delusions. For example, the initial belief may be that the police are watching him night and day; the secondary delusion ‘explains’ that this is because he has secret information about aliens which the authorities do not wish divulged. The better organized the delusions, the more convincing are the ‘explanations’, even to outsiders.
Not all primary delusions arise suddenly and, in fact, it must be presumed that in most cases the suddenness is more apparent than real. Almost certainly, unless the delusion is the result of an acute brain dysfunction such as may follow a head injury or delirium, there is a lead-up process, which may be accompanied by the aforementioned Wahnstimmung, a mood state compounded of anxiety, perplexity, and a sense of impending crisis. When the delusion crystallizes, the delusional mood often disperses and is replaced by a sense of revelation and of certainty. It seems likely that this phenomenon occurs in a proportion of delusional disorder patients and it often happens that, at the moment of revelation, some coincidental but irrelevant circumstance is picked upon to explain the appearance of the new belief. For example, a media event, a thunderstorm, a chance telephone call, etc., may thereafter be, in the patient’s mind, the ‘cause’.
While we regard delusions as one of the most characteristic elements of all the psychotic illnesses and a sine qua non in the diagnosis of delusional disorder, clear-cut description, and delineation have proved elusive despite many years of study and experiment.(10) In fact, it would seem that none of the characteristics of delusion which we traditionally accept stand up completely to scientific scrutiny. In particular, nowadays the so-called bizarreness of a delusion has been shown to have little or no distinguishing value.(11)
Much of the classical work on delusions was done in pretreatment times when the chronic condition was readily available for study in institutions. In the present era our aim is to diagnose psychotic disorders as early as possible, sometimes even before frank delusions are evident, and to begin treatment at once. Neuroleptics rapidly interfere with many psychopathological processes; they certainly suppress delusions, although not necessarily permanently. Of course this makes ongoing experimental observations of delusions, especially of the acute variety, all but impossible in clinical circumstances. Psychiatrists find themselves in the paradoxical situation of diagnosing illness because of the presence of delusions whose scientific validity is largely unsubstantiated, and then causing these to disappear before they can be verified properly. Nevertheless, until we have more objective means of making diagnoses it remains essential that, as far as we can, we recognize delusions when they occur and separate them from other abnormal psychopathological appearances.
How can a clinician deal with this? Firstly it seems inescapable that he or she be both experienced and insightful. Given these qualities, it often does seem possible to have an informed sense of whether a belief is true or false and, if the latter, whether it is being held with delusional intensity. A key element in the decision is a comparison between the patient’s current beliefs and those he
habitually held, and here a corroborative account from an informed outside source is usually necessary.
habitually held, and here a corroborative account from an informed outside source is usually necessary.
The observer’s educated suspicion that a delusion is present is the starting point, but it is evident that that suspicion has to be aroused by the context of the apparently delusional idea because, no matter how isolated it appears to be, it nearly always occurs in the setting of a mental disorder whose other features may indicate a specific psychiatric diagnosis. Illogically, instead of recognizing the delusion and using it to make a definite diagnosis, we develop the conviction that we are dealing with a probable psychosis and thereafter judge all the patient’s utterances in light of that. While he may indeed be experiencing delusions, it is essential that we do not automatically assume that anything the psychotic individual says has of necessity to be of a delusional nature.
We must accept that we cannot be absolute in our recognition of a delusion. In addition to the illness context we base our estimate on a series of nuances, no one of which is pathognomonic but an accumulation of which becomes increasingly convincing. The abnormalities to be sought are as follows:
1 An idea or belief is expressed with unusual persistence or force.
2 As far as we can tell, the idea is not typical of the individual’s previously prevailing thinking and is not shared by his or her social community.
3 The idea appears to exert an undue influence on the person’s life and consequently the way of life is altered to an extraordinary degree.
4 Despite the significance to the patient of the belief, he or she often displays secretiveness or resentment when questioned about it.
5 The individual tends to be humourless and oversensitive about the belief.
6 There is a quality of ‘centrality’; no matter how strange the belief or its consequences, the patient rarely questions that incredible things are happening to him or her. For example, why should a perfectly ordinary harmless person be singled out for constant surveillance by the security agencies? But this is simply accepted.
7 Attempts to contradict the belief are likely to arouse an inappropriately strong emotional reaction, often with irritability and hostility and with a superciliousness that may be a form of grandiosity.
8 On reflection the belief appears unlikely to the observer, but at the time of history-taking the vehemence of its expression may temporarily disguise its improbability.
9 The patient is so emotionally overinvested in the idea that it swamps other elements in the psyche, and many everyday activities are neglected.
10 If the delusion is acted out, uncharacteristic behaviours, sometimes involving violence, will occur which may be partly understood in terms of the abnormal belief.
11 Others who know the patient well will usually observe that his or her thinking and behaviour are alien, unless folie à deux is present when, paradoxically, the other person’s denials of abnormality are themselves possible confirmation of the presence of delusion.
12 An odd feature of delusions is that, no matter how strongly they are held, when the patient is given the opportunity to obtain real proof he or she persistently evades accepting the opportunity.
13 One must always look for the features which frequently accompany delusions, especially suspiciousness, hauteur, grandiosity, evasiveness, and eccentric or threatening behaviour, as well as evidence of thought disorder, mood change, and hallucinations.
Particular features of delusions in delusional disorder
In addition to any of the above, in delusional disorder we find several other elements, which are of importance in leading to the diagnosis:
1 The delusional system is stable and is expressed or defended with intense affect and with highly rehearsed arguments. The form of logic used by the patient is very consistent but the propositions are based on false premises. Since the individual is so focused on his beliefs and is so self-assured, he often succeeds in making the enquirer feel inept.
2 The delusional system is markedly ‘encapsulated’, so that the beliefs therein and their accompanying symptoms are to a considerable extent separated from the rest of the personality which retains a good deal of normal function. However, the compelling force of the delusions often overshadows these normal aspects and this is increasingly so with advancing chronicity of the illness, when the tendency to express and act out the delusions may well increase.
3 When the individual is preoccupied with the delusional system there is strong emotional and physiological arousal, but when he or she is engaged on neutral topics, the arousal abates and an ordinary conversation can take place. Switching between normal and abnormal ‘modes’, sometimes very rapidly, is virtually pathognomonic of delusional disorder.
4 Because of the encapsulation of the delusions and the normal-abnormal switch just described, the patient may have phases of relative normality interspersed with psychotic periods. The switch can occur spontaneously or as a result of external provocation; the two are difficult to disentangle because the hypervigilant individual may perceive provocation in almost anything. Since it is a chronic illness the symptoms never remit, but if they are temporarily in the background the patient may converse and function almost normally and may have sufficient quasi-insight to keep the delusions concealed for the moment. Total denial of mental abnormality and resistance to psychiatric referral are almost universal in cases of delusional disorder and lead to severe underestimation of the illness’s frequency.
5 As a result of the features just described, many delusional disorder patients can continue to exist in society, sometimes with very abnormal but harmless beliefs but in other instances with highly malignant delusions, which they may or may not act out.
6 As will be repeatedly emphasized, delusional disorder must be diagnosed on the form of the illness and the content of the delusion is not used to make the primary diagnosis. On the other hand, the particular content is employed to categorize into subgroups, as will shortly be described.
Delusional disorders: clinical features
Official diagnostic criteria
The DSM-IV and ICD-10 criteria are shown in Tables 4.4.1 and 4.4.2, respectively.
As will be seen, the DSM-IV and ICD-10 descriptions are very similar in overall outline but with a number of rather striking minor differences. The following specific items should be noted:
1 DSM-IV uses the term ‘non-bizarre’ delusions; this criterion has been shown to have little or no validity.(11)
2 DSM-IV allows the presence of tactile and olfactory hallucinations, while ICD-10 mentions only auditory hallucinations; in practice most modalities may be represented but the important point is that they are relatively non-prominent and usually parallel to the content of the delusion(s).
3 DSM-IV says that delusions should have been present for 1 month and ICD-10 insists on 3 months. Both are guesses, but ICD-10 is probably right to err on the side of caution and it provides category F22.8 as a temporary niche until the definitive diagnosis emerges.
4 Both classifications exclude delusional illnesses due to organic brain disorder, medical illnesses, medication effects, or psychoactive substance abuse. In essence this is correct, especially in an illness of acute onset. However, as will be noted later, an apparently typical delusional disorder may arise as a long-term complication of any of these factors.
5 DSM-IV and ICD-10 agree emphatically that delusional disorder is not schizophrenia and DSM-IV notes that general functioning is not impaired. Both say that mood disturbance may accompany the delusional illness but is not a cause of it.
6 The list of subtypes according to delusional content is similar in both classifications, although ICD-10 adds self-referential and litigious themes.
Table 4.4.1 DSM-IV delusional disorder (297.1) | ||||||||||||||
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Table 4.4.2 ICD-10 persistent delusional disorders | ||||||||||||||||||
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7 Neither classification specifies that the essence of delusional disorder is a highly organized delusional system, largely encapsulated from normal aspects of the personality, although DSM-IV hints at this when it comments that functioning is not markedly impaired and behaviour is not obviously odd or bizarre. Neither comments that the patient can demonstrate alternating ‘normal’ and ‘delusional’ modes.
8 The ICD-10 category of ‘other persistent delusional disorders’ is vaguely described and is largely a catch-all heading or, as mentioned above, a temporary holding station. However, it could conceivably be used for the time being to subsume the unofficial delusional disorder diagnoses of paraphrenia and delusional misidentification syndrome.
9 Overall, DSM-IV and ICD-10 give rather laconic descriptions of delusional disorder and it will be necessary to flesh them out with relevant clinical details. This will be done after the next section on aetiological considerations.
General aetiological considerations in delusional disorders
It must be stressed that knowledge of aetiology in delusional disorder is scanty and highly speculative, largely because so little modern research has been conducted. What follows is an outline,
and certain other factors will be noted when we come to consider some of the illness.
and certain other factors will be noted when we come to consider some of the illness.
(a) Genetic factors
Changes in definitions of paranoia/delusional disorder over the years and the frequent confusion with schizophrenia make most studies all but impossible to interpret. Conclusions are inferential rather than evidence based. However, it seems well established(12) that delusional disorder and paranoid schizophrenia are less directly inherited than other forms of schizophrenia, and that there is little or no evidence of a genetic link between delusional disorder and schizophrenia.
There may be genetic links with certain severe personality disorders, especially of the paranoid and schizoid varieties, but these are difficult to substantiate. There does seem to be an excess of such disorders in relatives and premorbidly in delusional disorder patients themselves. It is suggested that paranoid and schizoid traits are particularly liable to lead to social isolation and aggravation of delusional tendencies.(13,14)
(b) Organic brain factors
Recent evidence from the study of delusional misidentification syndrome (see later) indicates that delusions of a very specific type may arise in association with certain well-defined brain insults. There are strong hints, but much less supportive evidence, to suggest that organic brain factors may also be important in cases of delusional disorder. For example, head injury may lead to the development of marked paranoid symptoms, and there is a long-established association between chronic alcoholism and pathological jealousy.(15) Old age itself may be linked to the onset of symptoms typical of delusional disorder, and early evidence of brain changes, especially in subcortical areas, is starting to appear in studies of various kinds of senile ‘paranoid’ illness.(16,17,18) Amphetamine and cocaine abuse(19) can induce delusional illness, as can therapeutic drugs, including L-dopa and methyldopa,(20) at times. Delusional illness induced by the brain effects of AIDS infection has been documented.(21)
Gorman and Cummings(22) have proposed that delusional illnesses of organic origin have underlying features in common, particularly temporal lobe or limbic involvement and an excess of dopamine activity in certain areas of the brain.
If organic factors predominate in a particular case, delusions must be seen as a secondary feature of an organic brain disorder. However, if the organic factors are subtle and of long duration, the clinical appearances may be those of a quite typical delusional disorder which, interestingly, may well respond to neuroleptic treatment as effectively as idiopathic cases. (In fact, ‘idiopathic’ may simply denote organicity at a more subtle level.) It is very possible that organic brain factors are much more common than we suspect in delusional disorder, especially in young males who have previously abused alcohol or drugs or have suffered a head injury in the past, and in older patients (more commonly female) who suffer from effects of an ageing brain.(23,24)
(c) Interplay with mood factors
We have already seen that DSM-IV and ICD-10 agree that mood symptoms may accompany delusional disorder but not cause it. Delusional and mood disorders are separate illnesses with their own natural histories and responses to treatment, yet there is a complex relationship between them, as is also the case with mood disorder and schizophrenia. For example, it is well documented that some cases of apparently typical mood illness, unipolar or bipolar, can progress to delusional disorder or schizophrenia over time. Conversely, cases which appear to be delusional disorder but with an episodic course may prove to be bipolar illness. There are a number of anecdotal reports of delusional disorder responding to antidepressant treatment, and it is more than likely that these represent a failure to recognize the true nature of a mood disorder associated with delusions.
Both depressive disorder and mania may be complicated by delusions. On the other hand, mood symptoms, especially dysphoria with anxiety, are a common complication of delusional disorder, while individuals with the grandiose subtype may show elation, which mimics mania but is far more sustained. In recovering delusional disorder, one may see postpsychotic depression of varying degrees of severity and this is described later. Suicide is not unknown in delusional disorder but its frequency is undetermined.
In many delusional disorder patients the illness is profoundly isolating and sets them at odds with the rest of the society, which often generates suspiciousness, dejection, anxiety, and agitation in the individual. It seems that a vicious circle results whereby the delusion induces distress and physiological overarousal which, in turn, reinforces the strength of the delusion and progressively diminishes reality input.
(d) Psychodynamic theories of causation
The psychodynamic literature continues to discuss aspects of ‘paranoia’ but often fails to differentiate clearly between trait, symptom, personality disorder, and psychotic illness. Most of the emphasis is on the persecutory aspect of paranoia, with only occasional references to other types of delusional content. Since psychotherapists rarely treat psychotic patients, their experience of delusional phenomena must actually be rare and their knowledge of the features correspondingly scanty. Their theoretical bias is to interpret the origins of paranoia in terms of psychological maldevelopment, ignoring the increasing weight of evidence that faulty brain mechanisms are involved. One must read the psychoanalytic literature on this particular topic with an ultracritical attitude, since it usually fails to provide adequate illness definitions or clear case reports and generates explanatory theories which are unjustifiably presented as proven facts.
(e) Conclusions regarding aetiology
No systematic research on paranoia took place for more than half a century and modern investigations into delusional disorder are only beginning to appear. Therefore it is premature to propose specific aetiological theories. However, a gathering weight of evidence does suggest a localized and relatively circumscribed brain disorder associated with the possible influence of abnormal neurotransmitter activity, probably involving dopamine overactivity. Whatever the original basis of delusional disorder, it certainly seems that provocative influences such as head injury, alcohol abuse, and ill effects of drugs may play a part, whereas speculation about psychological causations suggest that this is at most a secondary influence. There is an urgent need for the study of extended case series utilizing modern neurophysiological and neuropsychological investigative methods.
Delusional disorder: general features and introduction to the subtypes
We have already outlined the diagnostic criteria for delusional disorder in DSM-IV and ICD-10 and have amplified these with descriptions of many of the clinical phenomena associated with the illness. It has been emphasized that this is a stable and readily recognizable disorder, provided that the clinician is informed of the essential criteria and has dealt with at least several cases to familiarize him- or herself with its very characteristic ‘feel’. With this experience it becomes much more possible to delve under the prominent symptoms related to delusional content and to discern the underlying form of the illness. However, it is the predominant delusional content in an individual case, and the symptoms and behaviours related to this, which decide how a patient will present for assessment. Therefore we shall consider the main subtypes in some detail. It cannot be stressed enough that these are not separate types of illness, but variants on a single psychopathological theme.
All cases of delusional disorder occur in clear consciousness and have a stable and persistent delusional system which is relatively encapsulated. Since much of the personality remains remarkably intact, a considerable degree of social functioning is retained in many cases. The patient experiences a heightened sense of self-reference within the delusional context and ordinary events take on unusual significance. He or she clings to the delusion with fervid intensity and spurns any suggestion that a mental illness is present. Outside the delusional system the patient shows quite normal thinking, affect, and behaviour, but there is a marked tendency for gradual pushing to one side of these normal aspects. The retention of such a degree of normality makes the illness totally different from schizophrenia.
Earlier it has been indicated that the DSM-IV criterion of non-bizarreness is unhelpful, although in all cases of delusional disorder the delusions are relatively well structured, coherent, and consistent, and the logic would often be acceptable if it weren’t that its basic premises are irrational. Many affected individuals can maintain overtly normal activities, at least in public, but increasing pressure of the delusion tends to cause corresponding responses in behaviour; these may be channelled socially, as in hypochondriacally deluded patients who utilize medical resources, albeit excessively, or antisocially, as in the aggression of the jealously deluded individual. Mood abnormalities are common as a response to the effects of the illness.
Hallucinations do occur in some cases and may affect any modality, but they are often difficult to assess and to differentiate from delusional misinterpretations and illusions. Widespread persistent hallucinations in more than one sensory sphere should make one cautious about the diagnosis of delusional disorder.
The illness appears to affect men and women approximately equally, but it is not clear if this is true of all subtypes. Despite older assertions that the illness is restricted to the middle-aged and elderly, the age of onset can actually be from late adolescence to extreme old age, with male patients appearing on average to experience earlier initiation. Some patients behave in an eccentric or fanatical fashion and, as a group, delusional disorder sufferers are excessively likely to be unmarried, divorced, or widowed, probably reflecting restriction of affective responses and some isolative tendencies. Despite this, the condition can be compatible with marriage and continued employment. The premorbid personality is usually described as asocial and there may indeed be an excess of long-standing schizoid and paranoid personality disorders. However, when a patient makes a good recovery there may be little evidence of this, and it is possible that in some cases a ‘personality disorder’ is actually the prolonged and insidious prodrome of the illness.
Onset may be gradual or acute. In the latter the patient often identifies a precipitating stressor, which is difficult to confirm (e.g. the person who has a delusion of skin infestation may attribute it to a single insect bite many years previously). While most individuals are secretive about their abnormal beliefs or express them by such means as physical complaints or legal processes, a certain number actually utilize them, perhaps within the context of an extreme religious sect or by becoming an excessively insistent agitator on some social issue. Disinhibited and overtly aggressive behaviour seems more likely to occur in males, at times leading to clashes with the authorities.
In all cases of delusional disorder, no matter what the nature of the delusional theme, the investigator should look for the relatively unique feature of the illness—the patient’s ability to move between normal and delusional modes of thinking. In the former there is relatively calm mood, reasonable rapport, and appropriate emotional responses, whereas in the latter there is overalerting, suspiciousness, and the sense that the person is being remorselessly driven by the delusional beliefs. This situation is difficult for the inexperienced observer to comprehend, since it is inconceivable to most people that someone who can appear perfectly rational at one moment can almost instantaneously change to a possessed irrational being—and then back again just as quickly. In a sense the same patient is both sane and insane, and when in the latter mode may be ultrapersuasive about the acceptability of his or her beliefs. One may imagine the plight of a lawyer faced with a client who has committed some uncharacteristically outrageous act as a result of a delusion, who can then discuss his case with apparent insight and logic, and even genuine remorse, but who nevertheless remains totally self-justifying. As a corollary, the client will usually deny the possibility of mental illness and often refuses to cooperate with psychiatric assessment. He may also refuse to cooperate with the legal process, to his knowing detriment.
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