Delusional disorder: Retrospective analysis of 86 Chinese outpatients

Authors


Correspondence address: DrChia-YihLiuMD Department of Psychiatry, Chang Gung Memorial Hospital, Kuei-San, Tao-yuan 333, Taiwan

Abstract

Patients who visited the psychiatric outpatient service of Chang Gung Medical Centre, Tao-Yuan, Taiwan during an 8-year period were studied retrospectively. Among the 10 418 outpatients, 86 (0.83%) were diagnosed as having DSM-IV delusional disorder (DD), including 61 (70.9%) with persecutory type, 12 (14.0%) with the mixed type, seven (8.1%) with jealous type, two (2.3%) with somatic type, two (2.1%) with unspecified type, one (1.2%) with erotomanic type, and another one with grandiose type. The ratio of women to men was 0.86. The mean age at onset was 42.4 ± 15.41 years, with women being older than men. Thirty-seven cases (43.0%) presented with depressive symptoms at their first visit. Subjects were divided into four groups: persecutory type, jealous type, mixed type and others. There were no significant differences between the four groups in terms of gender, age at onset, time-lapse before seeking psychiatric help, the presence of hallucination or the presence of depression.

INTRODUCTION

Nearly 70 years after Krapelin first separated paranoia from dementia precox and manic-depressive insanity, 1 Cameron wrote, ‘there are no reliable statistics concerning the incidence of paranoia and paranoid reactions’. 2 This statement remains valid today.

The diagnosis of delusional disorder (DD) is complicated by the fact that patients with DD often do not seek psychiatric help. They often complain of depression or anxiety, while denying the delusion. 3 Sometimes they may present to internists, surgeons, dermatologists, policemen or lawyers rather than psychiatrists. 4 Despite the long history of DD as a psychiatric disease classification, relatively little is known about the demographic characteristics of patients with DD, or the frequencies of the various subtypes of this disorder. A previous review of the nosologic validity of paranoia or ‘simple’ DD 3 (defined by the clearly specified absence of hallucinations) disclosed only four studies that reported a limited number of demographic characteristics of DD. However, the sample sizes of these studies were small.

Recently, Yamada et al. investigated 51 Japanese DD patients 5 using DSM-III-R criteria. 6 In their report, women were preponderant and persecutory subtype comprised half of the subjects.

The DSM-IV published in 1994 added a new subtype of DD, the mixed type. 7 This diagnosis is reserved for cases in which no single delusion type predominates. Reviewing the literature, there have been no studies of DD that have employed the DSM-IV criteria. Research into DD in Chinese patients has also been largely neglected. The aims of this study were to investigate the characteristics of Chinese patients with DD in accordance with the current diagnostic criteria.

SUBJECTS AND METHODS

We retrospectively reviewed the records of patients who visited our outpatient psychiatric service from January 1991 to April 1998. Two psychiatrists (MCH and CYL) studied all medical records, including special charts for initial visit and outpatient service records. The diagnosis of DD, age at onset, age at first visit, sex, symptomatology, and DD subtypes were determined by concensus between the two psychiatrists. Patients with suspected organic etiologies and uncertain diagnosis were excluded.

If a diagnosis was initially made by DSM-III-R criteria, it was upgraded according to the DSM-IV. The data chosen for analysis included gender, age at onset, time-lapse before seeking psychiatric help, associated hallucinations, depressive symptoms, and the subtypes of DD. We further divided patients into four groups for comparison, namely: persecutory type, jealous type, mixed type, and others (including unspecified, grandeur, somatic, and erotomanic subtypes). The definition of associated hallucination followed the DSM-IV criteria: tactile or olfactory hallucinations related to the delusional theme, or transient and non-prominent other hallucinatory experiences. Patients who had prominent auditory or visual hallucinations were excluded from this study.

The subjects were then grouped into ‘DD with depression’ and ‘DD without depression’, in order to analyze whether there were different characteristics between the two groups.

The data were analyzed by Student’s t-test and one-way ANOVA for continuous variables and Chi-squared test for categorical variables. The level of significance was set at P < 0.05.

RESULTS

During the 8 year 4-month period, 10 418 patients visited our outpatient clinic. There were 4615 men (44.3%) and 5803 women (55.7%), with a mean age of 37.3 ± 14.56 years. Among them, diagnosis of DD was made in 86 cases (0.83%). There were 44 men and 42 women. The age at onset ranged from 17 to 86 years, with an average of 42.4 ± 15.4 years. Women were significantly older at onset than men (women, 46.0 ± 16.1; men, 38.7 ± 14.2, t = 2.20, d.f. = 84, P < 0.05). The mean duration from symptom onset to first psychiatry clinic visit was 2.4 ± 3.4 years, and did not differ significantly between the sexes.

The associated auditory hallucinations were noted in 10 cases (11.6%), followed by related tactile hallucinations (n = 5, 5.8%), visual hallucinations (n = 2, 2.3%), and olfactory hallucinations (n = 2, 2.3%). The subtype of DD (according to DSM-IV criteria) most frequently encountered was the persecutory type (n = 61, 70.9%), followed by the mixed (n = 12, 14.0%), jealous (n = 7, 8.1%), somatic (n = 2, 2.3%), unspecified (n = 2, 2.1%), erotomanic (n = 1, 1.2%), and grandiose (n = 1, 1.2%) types.

Patients were divided into four groups according to their subtype. There were no significant differences between the four groups in terms of gender, age at onset, time-lapse before seeking psychiatric help, frequencies of associated hallucinations and frequencies of associated depression ( Table 1).

Table 1. . Demographics and statistics between subtypes according to DSM-IV criteria Thumbnail image of

Among the 12 mixed type cases, six had jealous and persecutory delusions, five had somatic and persecutory delusions, and one had somatic, jealous, and persecutory delusions.

Thirty-seven (43.0%) patients presented with depressive symptomatology at their first visit. Among them, seven had parasuicide history. There were no significant differences between those with and without depression in terms of sex, age at onset, time-lapse before seeking psychiatric help, and associated hallucinations.

DISCUSSION

The prevalence of DD in the Western population ranges from 0.24 to 0.30%, with a sex ratio F:M = 1.18. 8 In Taiwan, the lifetime prevalence of DD is 0.48% in cities, 0.67% in townships, and 0.33% in rural villages. 9 Kendler reviewed the literature and found that seven of nine studies reported a preponderance of female patients at first admission of DD. 8 Yamada et al. also reported a 3:1 female:male ratio among 51 DD patients seen over a 6-year period in Japan. 5 The ratio of women to men in our study was 0.86, which is markedly lower than other reports. In Hwu et al.’s epidemiological study in Taiwan, the prevalence of DD is slightly higher in men than it is in women in cities and townships, and is slightly higher in women in rural villages. 9 However, the differences are not statistically significant. In the present study, women comprise 55.7% of the outpatient population. This result implies that women with DD in Taiwan are less willing to seek psychiatric help. However, this point requires more investigation, as the results were from a single center. Women were significantly older than men at the time of onset in our study, this is in concordance with Yamada et al.’s finding. 5 Another epidemiological study reported that the age at onset of DD may range from 18 to 80 years. 4 In our study, the age of onset ranged from 17 to 85 years.

There is a paucity of literature on the frequencies of subtypes of DD. Someya et al. reported that the most common subtype of DD was persecutory type (64%), followed by the jealous type (19%). 10 Yamada et al. reported that the most common encountered was the persecutory type (51.0%), followed by the somatic type (27.5%), and the jealous type (13.7%). 5 We also found that the majority of the cases were persecutory type, followed by the mixed type. The mixed type is a new classification of DSM-IV. When we adopted the DSM-III-R criteria for all cases, the frequency of subtypes is similar to the above studies: persecutory type (n = 61 cases, 70.9%), jealous type (n = 12, 14.0%), and somatic type (n = 5, 7.0%).

Our study revealed no significant differences between these subtypes in sex, age at onset, time-lapse before seeking psychiatric help, frequencies of associated hallucinations, or frequencies of associated depression. Rudden et al. reported no significant difference in delusional contents, including grandiose, jealous and somatic delusions, except for erotic delusions, between the genders. 11 Yamada et al. found no significant difference in the frequency of subtypes of DD between the sexes. 5 Our results generally support their findings.

We found a high percentage of DD patients had depressive symptomatology, including seven cases with a parasuicide history. Marino et al. also found a high frequency of mood disturbances in DD patients (50.7%). 12 These findings warrant attention. Chiu et al. reported four cases of DD with depression. 13 They suggested that depression is a reaction to the delusional condition. While in Marino et al.’s study, about 42% of DD patients with depression, the onset of mood disturbance preceded the onset of delusion by a considerable interval of time. 12 Some psychopathologists have described a prodromal decompensatory and disintegrative phase of DD, which is predominately affective and extremely unpleasant. 14,15 Some patients with DD responded to antidepressants and neuroleptics further suggesting the possibility of an affective origin for some forms of DD. 16

In the present study, depressive cases were defined as depressive symptomatology noted at their first visit. The time of onset and course of depression was difficult to determine. This is a limitation in a retrospective study.

The new subtypes, mixed type in DSM-IV, also need more clarification. In this study, 12 cases fulfilled the criteria of mixed subtypes. However, the sequence and course of different themes of delusions in each patient could not be defined clearly. This is another interesting topic for future DD research.

Although the small number of somatic, unspecified, erotomanic, and grandeur subtypes limit our further comparison between the seven subtypes of DD, this remains the first report on Chinese patients with DD. For more detailed information about this illness, prospective studies with even larger samples are recommended.

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