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Aim: The aim of this work is to investigate differences between two non-schizophrenic, non-organic psychotic disorders, namely persistent delusional disorders (PDD) and acute and transient psychotic disorders (ATPD) according to ICD-10.
Method: In a prospective and longitudinal study, we compared all 43 inpatients with PDD who were treated at Halle-Wittenberg University Hospital during a 14-year period to a previously investigated cohort of 41 patients with ATPD in regard to demography, long-term symptomatic outcome, and social consequences. Sociobiographical data were collected using a semi-structured interview. Follow-up investigations were performed at a mean of 10–12 years after the onset of the disorder using standardized instruments.
Results: With the exception of the duration of the psychotic symptoms, the PDD patients were significantly different from the ATPD patients on various levels, such as sex ratio (female predominance only in ATPD), age at onset (older in PDD), the number of preceding stressful life-events in the index hospitalization (more frequent in ATPD), richness and variety of symptoms (higher in ATPD), and persistence of positive psychotic symptoms (in PDD). Patients with PDD had significantly less re-hospitalizations during the course of their illness. Long-term outcome was marked by chronicity of delusional symptoms and lower global functioning in PDD than in ATPD, while negative symptoms and loss of independence were infrequent in both conditions.
Conclusions: PDD differs from ATPD not only in the duration of the psychotic symptoms, but also in a variety of significant variables. They appear to be two separate entities within a psychotic spectrum.
PERSISTENT DELUSIONAL DISORDERS (PDD) and acute and transient psychotic disorders (ATPD) are two psychotic disorders that are supposedly distinct from schizophrenia in terms of their symptoms, pathogenesis, and prognosis.1–3 For both PDD and ATPD, however, the nosological status is disputed, and empirical data on both disorders are scarce because of their low frequency and a focus of research on patients with schizophrenia.4
According to ICD-10, PDD (F22.0) is a psychotic condition in which delusions constitute the most conspicuous or the only clinical characteristic, and must be present for at least 3 months. Subtypes of PDD may be specified as the persecutory type, the litigious type, the self-referential type, the grandiose type, the hypochondriacal (somatic) type, the jealous type, and the erotomanic type.5 In the DSM-IV, the diagnosis of delusional disorder (DD) (DSM-IV: 297.1) is operationalized in a largely analogous way.6
The creation of the concept of acute and transient psychotic disorders (ATPD) by the World Health Organization (WHO) is another consequence of the fact that some psychotic disorders could not be allocated to either of the two broad dichotomous groups: dementia praecox (later named schizophrenia) and manic-depressive insanity (later named affective disorder).7,8 The diagnosis of ATPD requires an acute (within 2 weeks) onset of psychotic symptoms and remission within 3 months (or within 4 weeks when schizophrenic symptoms are present). Several subtypes are defined according to the presence or absence of typical ‘polymorphic features’ and schizophrenic first-rank symptoms.9 The benign long-term course of ATPD has been confirmed in a follow-up study that was conducted by our group.9–11
PDD and ATPD have in common the development of psychotic symptoms in the absence of severe other psychopathological abnormalities. The nosological status of both disorders is disputed. Since a detailed knowledge of their long-term course is crucial for understanding these disorders and to establish their clinical validity, the principal aim of the present study was to conduct a longitudinal comparison of patients with either PDD or ATPD. To this end, we combined data from a long-term follow up of a cohort of patients with PDD with data of a group of patients with ATPD. Both groups of patients were diagnosed and treated as inpatients in the same institution, and then investigated and followed up using identical methodologies. We set out to determine common features as well as differences in sociodemographic variables, aspects of the acute episode, and long-term course and outcome of the two disorders. We hypothesized that both disorders have a favorable outcome, yet each displays a distinct pattern in terms of its demography, the long-term symptomatic outcome, and the social consequences.
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PDD and ATPD are psychotic disorders that both differ in their course and outcome from schizophrenia and whose nosologies are disputed.3,8 Although positive psychotic symptoms, namely delusions, are characteristic of both disorders, afflicted patients do not generally develop progressive negative symptoms.3,9 It is unclear why repeated or persistent delusional symptoms occur in patients with PDD or ATPD without the severe deterioration that occurs in patients with schizophrenia.
To the best of our knowledge, a comparative study of the two psychiatric disorders has only been reported by Jørgensen21 in a sample of 88 inpatients with delusions of different origin. The strength of the present study is that this investigation was a comparative longitudinal study of two infrequently occurring psychotic disorders whose study patients were recruited from the same institution, and then assessed using identical standardized instruments. The main limitation of the study is the rather small number of study patients, even though we included all patients with PDD admitted over a considerable period of time. This limitation is inherent to most investigations of infrequent psychiatric conditions. Some of the results reflect differences in the diagnostic concepts of PDD and ATPD. The core findings, however, are not trivial because they either relate to features not included in the operational diagnostic criteria or verify supposed characteristics of the disorders by prospective longitudinal observations. To obtain samples as homogenous as possible, patients with a diagnostic change to schizophrenia or schizoaffective disorder were excluded from the longitudinal analyses. We cannot exclude that a small number of patients would undergo diagnostic shift at a still later time.
The results of the present investigation highlight several interesting differences between PDD and ATPD that persisted when analysis was restricted to the polymorphic subtype of ATPD. PDD has a later onset than ATPD, and has the same prevalence in men and women, whereas ATPD occurs much more frequently in women than it does in men.9 Interestingly, the duration of inpatient treatment for PDD is not markedly longer than that of ATPD. Although we did not detect a statistically significant effect in our sample, it is noteworthy that the number of patients with PDD who discharged themselves from hospital against medical advice was twice as high as the number of patients with ATPD. This pattern is consistent with the experience that many patients with PDD are delusional for long periods, and do not seek medical assistance.3 Precipitating factors that were associated with onset of the disorder were found in 44% of the patients with PDD, and this number was not significantly different from that found in the patients with ATPD (46%). This finding is in agreement with the finding of Opjordsmoen et al.,22 who studied the influence of preceding life events in delusional disorders. However, subsequent hospitalizations in PDD patients seem to be less often preceded by a stressful life-event than subsequent episodes of ATPD, as suggested by the finding of a significant difference in the number of stressful life-events that preceded the index hospitalization (which is not identical with the onset of the disorder).
In the evaluation of relapses (or re-hospitalizations), one has to bear in mind that the delusional symptoms in most patients with PDD persisted continuously during the follow-up period. For these patients, hospitalizations during follow up did not necessarily mean a dramatic deterioration of their symptoms. In contrast, a relapse in the ATPD patients always involved the sudden re-appearance of de novo psychotic symptoms while they were in a state of remission. In other words, while almost all relapses led to a hospitalization in the ATPD patients, PDD patients may be chronically symptomatic without being re-hospitalized. This difference in the acuteness of symptoms explains why re-hospitalizations were significantly less frequent in the PDD patients than in the ATPD patients. This holds true whether one examines the number of study patients who were hospitalization-free or the mean number of hospitalizations per year that occurred during the follow-up period.
The outcomes of the two diagnostic groups differed in some, but not all domains. The present study confirms the absence of clinically relevant negative symptoms in both disorders over a follow-up period of more than 10 years. However, the persistence of positive symptoms, namely delusions, prevailed in the PDD patients, and this persistence of delusions is also reflected by markedly lower GAF scores in these patients at follow up when compared with the ATPD patients. This result is in agreement with the study of Jørgensen21 who found similar differences in global functioning in his 8-year follow-up study of 88 PDD and ATPD patients with delusional beliefs. With respect to social outcome, PDD patients have a slightly less favorable course than ATPD patients as indicated by the DAS scores. However, the PDD subjects remained independent, had a stable partnership, and stayed in treatment almost as often as the ATPD patients, and their rates of early retirement did not exceed those of the ATPD patients. The findings of our study thus confirm Winokur's23 suggestion that a delusional disorder does not destroy the ability of the individual to function socially, but does create problems in daily living because of interpersonal conflicts.
In conclusion, the results of the present investigation show that, in contrast to ATPD, the delusional symptoms in PDD are highly preserved and tend to remain stable over many years. They can still be found at long-term follow up, and they affect the general functioning and, to a lesser degree, social adaptation. Both disorders share a relative absence of negative symptoms and the preservation of independence over the long term. Why psychotic symptoms remit in ATPD, but persist in PDD, remains unclear. The dissimilarities in sex ratio and the age at the time of onset of the two disorders may indicate nosological differences. These differences could be explored in future studies that embrace neuropsychological and neurobiological aspects of the two disorders.