Delusional disorder and schizophrenia: a comparison of the neurocognitive and clinical characteristics in first-episode patients

Age-matched versus non-age-matched comparison of clinical and functional differences between delusional disorder and schizophrenia: a systematic review

Background

It has been widely suggested that delusional disorder (DD) differs from schizophrenia (SZ). However, whether the two disorders are truly distinct from each other is inconclusive as an older age of onset is closely linked to a better prognosis in psychotic disorders. In order to delineate the potential influence of age on outcomes, we undertook a systematic review on the clinical and functional differences between DD and SZ in age-matched and non-age-matched cohorts.

Methods

Electronic databases were retrieved up to May 2022. Included studies were analyzed with reference to statements about clinical, cognitive and functional differences between DD and SZ.

Results

Data synthesized from 8 studies showed (1) extensive effects of age on positive, general psychopathological symptoms and functioning, but (2) consistent differences between the two disorders in terms of negative symptoms and hospitalizations regardless of age matching.

Conclusion

There is currently insufficient evidence to conclude whether DD is completely distinct from SZ, but our review showed support for the confounding effect of age in comparisons of psychotic disorders with different ages of onset. Future studies shall take note of other possible confounding variables, methods of age-matching and the importance of longitudinal information in deducing whether the two disorders differ from each other in course and outcome.

Functional and clinical outcomes of delusional disorder and schizophrenia patients after first episode psychosis: a 4-year follow-up study

BACKGROUND

Literature has typically associated delusional disorder with a poorer prognosis relative to schizophrenia, without considering the confounding effect of age despite the differential age of onset. This study therefore aims to investigate the diagnostic stability, clinical, functional, and neurocognitive differences of Chinese first-episode psychosis age-matched patients with delusional disorder and schizophrenia at four years.

METHODS

71 delusional disorder and 71 age-matched schizophrenia patients were followed up for four years after their initial episode. Their symptoms, insight in psychosis, side effects of medication, medication compliance, functioning, and neurocognitive performance were assessed at four years.

RESULTS

At four years, 65% of DD patients maintained the same diagnosis, while the rest shifted to SZ. Only those without a diagnostic shift were included in the analysis. Delusional disorder patients (n = 46) experienced greater general psychopathology and poorer insight, but better attitude towards medication than schizophrenia patients (n = 71). Social and occupational functioning, quality of life, and cognitive functioning, however, were similar in delusional disorder and schizophrenia patients.

CONCLUSIONS

Results indicate that delusional disorder is less diagnostically stable than schizophrenia. Their outcomes in a Chinese population were largely similar at four years after removing the confounding age factor, implying that delusional disorder and schizophrenia may not be as distinct as previously thought.

Striatal dopamine synthesis capacity and its association with negative symptoms upon resolution of positive symptoms in first-episode schizophrenia and delusional disorder

RATIONALE

How striatal dopamine synthesis capacity (DSC) contributes to the pathogenesis of negative symptoms in first-episode schizophrenia (SZ) and delusional disorder (DD) has seldom been explored. As negative symptoms during active psychotic episodes can be complicated by secondary influences, such as positive symptoms, longitudinal investigations may help to clarify the relationship between striatal DSC and negative symptoms and differentiate between primary and secondary negative symptoms.

OBJECTIVE

A longitudinal study was conducted to examine whether baseline striatal DSC would be related to negative symptoms at 3 months in first-episode SZ and DD patients.

METHODS

Twenty-three first-episode age- and gender-matched patients (11 DD and 12 SZ) were consecutively recruited through an early intervention service for psychosis in Hong Kong. Among them, 19 (82.6%) patients (9 DD and 10 SZ) were followed up at 3 months. All patients received an ¹⁸F-DOPA PET/MR scan at baseline.

RESULTS

Baseline striatal DSC (K^occ;30-60) was inversely associated with negative symptoms at 3 months in first-episode SZ patients (r_s =  - 0.80, p = 0.010). This association remained in SZ patients even when controlling for baseline negative, positive, and depressive symptoms, as well as cumulative antipsychotic dosage (β =  - 0.69, p = 0.012). Such associations were not observed in first-episode DD patients. Meanwhile, the severity of negative symptoms at 3 months was associated with more positive symptoms in DD patients (r_s = 0.74, p = 0.010) and not in SZ patients.

CONCLUSIONS

These findings highlight the role of striatal DSC in negative symptoms upon resolution of active psychotic episodes among first-episode SZ patients. Baseline striatal dopamine activity may inform future symptom expression with important treatment implications.

20-Year Prospective, Sequential Follow-Up Study of Heterogeneity in Associations of Duration of Untreated Psychosis With Symptoms, Functioning, and Quality of Life Following First-Episode Psychosis

OBJECTIVE

Determining the extent to which relationships between duration of untreated psychosis (DUP) and outcome endure longitudinally across the lifetime course of psychotic illness requires prospective, systematic studies of epidemiologically representative incidence cohorts across decades. Transience, persistence, or heterogeneity in associations between DUP and distinct outcome domains are yet to be investigated over such time frames.

METHODS

Prospective, sequential follow-up studies of an epidemiologically representative first-episode psychosis incidence cohort in Ireland were conducted at 6 months and 4, 8, 12, and 20 years (N=171). Linear mixed-model analyses were applied to determine whether prospective associations of DUP with symptoms, functioning, and quality of life were consistent or varied across psychotic illness trajectory over a 20-year period. Evaluations included time, DUP quartile, and DUP quartile-by-time interaction effects.

RESULTS

Prospective, sequential follow-ups showed positive and negative symptoms, function, and quality of life to exhibit distinct trajectories of improvement in relation to shorter DUP. Despite heterogeneity in course and relationship to premorbid features, associations between shorter DUP and greater improvement were still evident 20 years after the first psychotic episode. Across the long-term course of psychotic illness, trajectories of association between shorter DUP and better outcome differed between domains of psychopathology, functionality, and quality of life. Nevertheless, such associations with shorter DUP were sustained for at least 20 years.

CONCLUSIONS

These profiles indicate that while associations between DUP and long-term outcome can vary according to the domain of outcome, they are sustained across decades in a manner that could not be fully accounted for in terms of premorbid features or lead-time bias.

Aberrant Gray Matter Volume and Cortical Surface in Paranoid-Type Delusional Disorder

INTRODUCTION

Delusions are core symptoms of schizophrenia-spectrum and related disorders. Despite their clinical relevance, the neural correlates underlying such phenomena are unclear. Recent research suggests that specific delusional content may be associated with distinct neural substrates.

OBJECTIVE

Here, we used structural magnetic resonance imaging to investigate multiple parameters of brain morphology in patients presenting with paranoid type delusional disorder (pt-DD, n = 14) compared to those of healthy controls (HC, n = 25).

METHODS

Voxel- and surface-based morphometry for structural data was used to investigate gray matter volume (GMV), cortical thickness (CT) and gyrification.

RESULTS

Compared to HC, patients with pt-DD showed reduced GMV in bilateral amygdala and right inferior frontal gyrus. Higher GMV in patients was found in bilateral orbitofrontal and in left superior frontal cortices. Patients also had lower CT in frontal and temporal regions. Abnormal gyrification in patients was evident in frontal and temporal areas, as well as in bilateral insula.

CONCLUSIONS

The data suggest the presence of aberrant GMV in a right prefrontal region associated with belief evaluation, as well as distinct structural abnormalities in areas that essentially subserve processing of fear, anxiety and threat in patients with pt-DD. It is possible that cortical features of distinct evolutionary and genetic origin, i.e. CT and gyrification, contribute differently to the pathogenesis of pt-DD.

The burden of disease in early schizophrenia - a systematic literature review

BACKGROUND

Schizophrenia is a heterogeneous disorder with a burden that can vary greatly depending on the severity and the duration. Previous research has suggested that patients in the earlier stages of schizophrenia (typically first-episode schizophrenia) benefit from effective early treatment, however, a comprehensive review of the burden specifically in this population has not been undertaken. A systematic literature review was therefore conducted to characterize the clinical, economic, and humanistic burden, as reported in naturalistic studies of schizophrenia populations specifically at an early stage of disease in comparison with healthy controls, patients with chronic schizophrenia, and patients with other psychiatric disorders.

METHODS AND MATERIALS

Searches were conducted in MEDLINE, MEDLINE In-Process, Embase, PsycINFO, and EconLit databases for records published between January 2005 and April 2019, and of relevant conference abstracts published between January 2014 and May 2019. Data were extracted from relevant publications and subjected to qualitative evaluation.

RESULTS

Fifty-two publications were identified for inclusion and revealed a considerable burden for early schizophrenia with regards to mortality, psychiatric comorbidities such as substance abuse and depression, poor social functioning, and unemployment. Comparisons with chronic schizophrenia suggested a greater burden with longer disease duration, while comparisons with other psychiatric disorders were inconclusive. This review uncovered various gaps in the available literature, including limited or no data on incarcerations, caregiver burden, and costs associated with early schizophrenia.

CONCLUSIONS

Overall, the burden of schizophrenia is apparent even in the early stages of the disease, although further research is required to quantify the burden with chronic schizophrenia and other psychiatric disorders.

Two Case Studies of Delusions Leading to Suicide, a Selective Review

Many questions pertaining to delusional disorder (DD) remain unanswered. It is unclear what syndromes to include under this category of psychotic illness and when to treat with antidepressants, cognitive therapy, or antipsychotic medication. DD is associated with psychiatric comorbidity, especially depression, and rates of suicidal behavior are high when the two conditions co-exist. In this selective review, we present two instances of suicide in the context of DD, one illustrating risks for the somatic subtype and the second, risks for the persecutory subtype. The frequency of suicidal behaviour in these two subtypes of DD is estimated at 8-21%. The literature suggests a prominent role for social emotions (shame, humiliation) in the pathway leading to suicide. In addition, risk factors found in our two patients point to factors such as poverty, living alone, vulnerable risk periods, stigma, and lack of trust in mental health services. Building trust may be the most effective preventive measure.

A longitudinal description of incompetent to stand trial admissions to a state hospital

OBJECTIVE

Evidence is clear that the nation is experiencing an increasing number of incompetent to stand trial (IST) admissions to state hospitals. As a result, defendants in need of treatment can wait in jail for weeks for admission for restoration. This study was conducted to better understand this growing population and to inform hospital administration about the characteristics of IST admissions.

METHODS

The study was conducted at the Department of State Hospitals (DSH) facility in Napa (DSH-Napa), a 1200-bed primarily forensic inpatient psychiatric facility located in northern California. The records of patients found IST and admitted to DSH-Napa for restoration of competence between the dates of 1/1/2009 and 12/31/2016 were eligible for inclusion in the study.

RESULTS

There were a total of 3158 unduplicated IST admissions available during the specified time period. Our data indicate that the number of admissions with more than 15 prior arrests increased significantly, from 17.7% in 2009 to 46.4% in 2016. In contrast, the percent of patients reporting prior inpatient psychiatric hospitalization evidenced a consistent decrease over time from over 76% in 2009 to less than 50% in 2016.

CONCLUSION

Our data add to the body of literature on the potential causes of the nationwide increase in competency referrals. The literature is clear that jails and prisons are now the primary provider of the nation's mental health care. Our data suggest that another system has assumed this role: state hospitals and other providers charged with restoring individuals to competence.

Short-term outcome of first episode delusional disorder in an early intervention population

BACKGROUND

Previous evidence suggests that delusional disorder has a later onset and better functional outcomes compared to schizophrenia. However, studies have not examined longitudinal outcomes in a first episode population, where confounding factors may be adjusted for.

METHODS

A nested case control study was designed within the National EDEN study; a cohort of 1027 first episode psychosis patients. Patients with a baseline diagnosis of delusional disorder (n = 48) were compared with schizophrenia (n = 262) at 6 and 12 months with respect to symptomatic and functional outcomes. Regression analysis was used to adjust for possible confounders.

RESULTS

Delusional disorder patients had a shorter duration of untreated psychosis compared to schizophrenia but were similar in other baseline characteristics. At baseline, delusional disorder patients had lower symptom scores but higher function scores compared to those with schizophrenia. At 12 months the differences persisted for symptoms scores but not overall function scores. After adjusting for baseline score, age and duration of untreated psychosis, differences between the groups remained significant only for Positive and Negative Syndrome Scale (PANNS) negative, general and total scores and recovery rates. There were no differences in changes in outcomes scores.

CONCLUSIONS

Delusional disorder in a first episode psychosis population presents with less severe symptoms, higher recovery rates and better functioning than schizophrenia, but at 12 months differences are ameliorated when adjusting for baseline differences.

A Psychopathological Comparison between Delusional Disorder and Schizophrenia

OBJECTIVE

To contribute to a better differential clinical categorisation of delusional disorder (DD) versus schizophrenia (SZ) and to add and complete evidence from previous clinical studies of DD compared to schizophrenia.

METHODS

A cross-sectional study using a clinical sample of 275 patients (132 patients with DD) was studied. Patients were consecutively attending public clinics located in urban and rural areas in both Andalusia and Catalonia (Spain). All participants met DSM-IV diagnostic criteria for either DD or SZ. Data were gathered on sociodemographics, illness duration, Barona-Index estimation of intelligence quotient (IQ), and global functioning, along with a thorough psychopathological assessment using the Positive and Negative Syndrome Scale (PANSS). Comparisons between both groups were calculated using χ², Student t, and multivariate analysis of covariance tests.

RESULTS

Patients with DD were older (mean [SD], 50.3 [14.6] years vs. 36.6 [11.1] years; t = 8.597; P ≤ 0.0001), were more frequently married (45.4% vs. 10.8%; χ² = 38.569; P ≤ 0.0001), and had a higher mean estimated premorbid IQ (111.4 vs. 105.4; t = 2.609; P ≤ 0.01). On the other hand, SZ patients were predominantly male (71.4% vs. 48.9%; χ² = 14.433; P ≤ 0.0001) and had greater work-related disability than DD patients (20.5% vs. 50.3%; χ² = 19.564; P ≤ 0.001). Overall, the DD group showed a less severe PANSS psychopathology than SZ group. Thus, total mean (SD) PANSS scores for schizophrenia and delusional disorder, respectively, were 76.2 (22.4) versus 54.1 (18.4) ( t = -8.762; P ≤ 0.0001). Moreover, patients with DD showed a better global functioning than those with SZ (62.7 [13.2] vs. 51.9 [16.9]; F = 44.114; P ≤ 0.0001).

CONCLUSIONS

DD is a milder and distinct disorder compared to SZ in terms of psychopathology and global functionality.

Transdiagnostic Extension of Delusions: Schizophrenia and Beyond

Delusion is central to the conceptualization, definition, and identification of schizophrenia. However, in current classifications, the presence of delusions is neither necessary nor sufficient for the diagnosis of schizophrenia, nor is it sufficient to exclude the diagnosis of some other psychiatric conditions. Partly as a consequence of these classification rules, it is possible for delusions to exist transdiagnostically. In this article, we evaluate the extent to which this happens, and in what ways the characteristics of delusions vary according to diagnostic context. We were able to examine their presence and form in delusional disorder, affective disorder, obsessive-compulsive disorder, borderline personality disorder, and dementia, in all of which they have an appreciable presence. There is some evidence that the mechanisms of delusion formation are, at least to an extent, shared across these disorders. This transdiagnostic extension of delusions is an argument for targeting them therapeutically in their own right. However there is a dearth of research to enable the rational transdiagnostic deployment of either pharmacological or psychological treatments.

The Clinical Features of Paranoia in the 20th Century and Their Representation in Diagnostic Criteria From DSM-III Through DSM-5

This review traces, through psychiatric textbooks, the history of the Kraepelinian concept of paranoia in the 20th century and then relates the common reported symptoms and signs to the diagnostic criteria for paranoia/delusional disorder in DSM-III through DSM-5. Clinical descriptions of paranoia appearing in 10 textbooks, published 1899 to 1970, revealed 11 prominent symptoms and signs reported by 5 or more authors. Three symptoms (systematized delusions, minimal hallucinations, and prominent ideas of reference) and 2 signs (chronic course and minimal affective deterioration) were reported by 8 or 9 of the authors. Four textbook authors rejected the Kraepelinian concept of paranoia. A weak relationship was seen between the frequency with which the clinical features were reported and the likelihood of their inclusion in modern DSM manuals. Indeed, the diagnostic criteria for paranoia/delusional disorder shifted substantially from DSM-III to DSM-5. The modern operationalized criteria for paranoia/delusional disorder do not well reflect the symptoms and signs frequently reported by historical experts. In contrast to results of similar reviews for depression, schizophrenia and mania, the clinical construct of paranoia/delusional disorder has been somewhat unstable in Western Psychiatry since the turn of the 20th century as reflected in both textbooks and the DSM editions.

Delusional disorder and schizophrenia: a comparative study across multiple domains

BACKGROUND

Delusional disorder (DD) is an under-researched condition and its relationship to schizophrenia (SZ) controversial. This study aimed to further characterize DD and to examine multi-domain evidence for the distinction between DD and SZ.

METHOD

Using univariate analyses we examined 146 subjects with DD, 114 subjects with paranoid SZ and 244 subjects with non-paranoid SZ on 52 characteristics from several domains including demographics, risk factors, premorbid features, illness characteristics, index episode features, delusional-related features, response to treatment and outcome. In a further step, we searched for independent associations of the examined characteristics with DD v. SZ.

RESULTS

Univariate analyses showed that DD differed from either form of SZ in 40 characteristics, the pattern of findings indicated that paranoid SZ was much more similar to non-paranoid SZ than DD. Relative to subjects with SZ, those with DD were more likely to have drug abuse before illness onset, better premorbid sexual adjustment, later age at illness onset, higher levels of affective symptoms and lack of insight, poorer response to antipsychotic medication, better functioning in the domains of personal care, paid work and social functioning; last, subjects with DD had fewer but more severe delusions and higher ratings of conviction of delusional experience than those with SZ. Predominance of jealousy and somatic delusions was confined to subjects with DD.

CONCLUSIONS

DD and SZ represent two distinct classes of disorders, the differential features of DD being of nosological, aetiological and therapeutic relevance.