Neuropsychological research in delusional disorder: a comprehensive review

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.

Climate change, vaccines, GMO: The N400 effect as a marker of attitudes toward scientific issues

While the psychological predictors of antiscience beliefs have been extensively studied, neural underpinnings of the antiscience beliefs have received relatively little interest. The aim of the current study is to investigate whether attitudes towards the scientific issues are reflected in the N400 potential. Thirty-one individuals were asked to judge whether six different issues presented as primes (vaccines, medicines, nuclear energy, solar energy, genetically-modified organisms (GMO), natural farming) are well-described by ten positive and ten negative target words. EEG was recorded during the task. Furthermore, participants were asked to rate their own expertise in each of the six topics. Both positive and negative target words related to GMO elicited larger N400, than targets associated with vaccines and natural farming. The results of the current study show that N400 may be an indicator of the ambiguous attitude toward scientific issues.

Psychotic symptoms associate inversely with social support, social autonomy and psychosocial functioning: A community-based study

BACKGROUND

Population-based studies exploring psychotic symptoms (PS) show that their prevalence in the community is higher than previously thought. Psychosocial functioning and social support are poorer among people presenting clinical and subclinical PS.

AIMS

We aimed to estimate the prevalence rate of PS in Andalusia and to explore the association between PS and psychosocial functioning, social support and social autonomy in a Southern European population.

MATERIAL AND METHODS

This is a cross-sectional study. We undertook multi-stage sampling using different standard stratification techniques. Out of 5496 households approached, we interviewed 4507 (83.7%) randomly selected participants living in the autonomous region of Andalusia (Southern Spain). The Spanish version of the MINI International Neuropsychiatric Interview was used to elicit PS. We also gathered information on socio-demographic factors, suicidality risk, psychosocial functioning, social support and social autonomy.

RESULTS

The overall prevalence of PS was 6.7% (95% CI: 5.99-6.45). PS were associated with lower age (OR 0.975; 95% CI (0.967-0.983); p < .0001), female gender (OR = 1.346; 95% CI (1.05-1.07) p = .018), not living in a rural area (OR = 0.677; 95% CI (0.50-0.90) p = 0.009), lower social support (OR = 0.898; 95% CI (0.85-0.94) p < .0001), lower scores on social autonomy (OR = 0.889; 95% CI (0.79-1.00) p = .050), having an increased suicidality risk score (OR = 1.038; 95% CI (1.005-1.07); p = .023) and having lower scores on psychosocial functioning (OR = 0.956; 95% CI (0.95-0.96); p < 0.0001).

CONCLUSIONS

Social outcomes seem to be strongly inversely associated with PS in spite of presumed higher levels of social support among Southern European cultures.

A population-based cross-sectional study of cognitive deficits in paranoia

This study sought to investigate the association between paranoia and performance in a range of neurocognitive domains using a large community sample. We conducted a cross-sectional survey of 4507 individuals within the PISMA-ep Study. We used a large community sample selected after multistage sampling using standard stratification techniques. Socio-demographic variables such as age, gender, educational level, urbanicity, and geographical region were recorded. The Spanish version of the Green Paranoid Thought Scale (S-GPTS) was used to assess paranoid thoughts. The Screening for Cognitive Impairment in Psychiatry (SCIP) was used to assess neurocognitive performance both globally and by domains (i.e., immediate and delayed verbal learning, working memory, verbal fluency and processing speed). Individuals with high S-GPTS paranoia scores showed significantly lower performance on global cognitive function and also on immediate (but not delayed) verbal learning, working memory, verbal fluency and processing speed. These results held statistical significance even after controlling for the effects of education and estimated IQ. We propose that cognitive deficits may be mediators of paranoid thinking formation and need to be considered when assessing patients with high levels of paranoia.

The role of dopamine dysregulation and evidence for the transdiagnostic nature of elevated dopamine synthesis in psychosis: a positron emission tomography (PET) study comparing schizophrenia, delusional disorder, and other psychotic disorders

There have been few studies performed to examine the pathophysiological differences between different types of psychosis, such as between delusional disorder (DD) and schizophrenia (SZ). Notably, despite the different clinical characteristics of DD and schizophrenia (SZ), antipsychotics are deemed equally effective pharmaceutical treatments for both conditions. In this context, dopamine dysregulation may be transdiagnostic of the pathophysiology of psychotic disorders such as DD and SZ. In this study, an examination is made of the dopamine synthesis capacity (DSC) of patients with SZ, DD, other psychotic disorders, and the DSC of healthy subjects. Fifty-four subjects were recruited to the study, comprising 35 subjects with first-episode psychosis (11 DD, 12 SZ, 12 other psychotic disorders) and 19 healthy controls. All received an ¹⁸F-DOPA positron emission tomography (PET)/magnetic resonance (MR) scan to measure DSC (K^occ;30-60 value) within 1 month of starting antipsychotic treatment. Clinical assessments were also made, which included Positive and Negative Syndrome Scale (PANSS) measurements. The mean K^occ;30-60 was significantly greater in the caudate region of subjects in the DD group (ES = 0.83, corrected p = 0.048), the SZ group (ES = 1.40, corrected p = 0.003) and the other psychotic disorder group (ES = 1.34, corrected p = 0.0045), compared to that of the control group. These data indicate that DD, SZ, and other psychotic disorders have similar dysregulated mechanisms of dopamine synthesis, which supports the utility of abnormal dopamine synthesis in transdiagnoses of these psychotic conditions.

Moderators and mediators of antipsychotic response in delusional disorder: Further steps are needed

Delusional disorder (DD) has been traditionally considered a relatively rare and treatment-resistant psychotic disorder. In the last decade, increasing attention has focused on therapeutic outcomes of individuals affected by this disorder. The aim of this paper is to provide a synthesis of the literature addressing two very important questions arising from DD research: (1) For which patients with DD do antipsychotic medications work best (the moderators of response); and (2) What variables best explain the relationship between such treatments and their effectiveness (the mediators of response). We searched PubMed and Google Scholar databases for English, German, French and Spanish language papers published since 2000. We also included a few classic earlier papers addressing this topic. Variables potentially moderating antipsychotic response in DD are gender, reproductive status, age, duration of illness, the presence of comorbidity (especially psychiatric comorbidity) and its treatment, brain structure, and genetics of neurochemical receptors and drug metabolizing enzymes. Antipsychotic and hormonal blood levels during treatment, as well as functional brain changes, are potential mediating variables. Some, but not all, patients with DD benefit from antipsychotic treatment. Understanding the circumstances under which treatment works best can serve to guide optimal management.

An Australian study of delusional disorder in late life

OBJECTIVES

There is a paucity of available research to guide clinical practice in delusional disorder (DD), particularly in late life. This study aimed to evaluate antipsychotic use and treatment outcomes in patients with DD aged 65 years and older. Secondarily, we sought to examine associated clinical features and socio-demographic variables.

DESIGN AND SETTING

This descriptive study reviewed all consecutive cases of DD referred to an Australian old age psychiatry service over a 12-year period. Fifty-five patients were assessed in the inpatient and/or community setting, with data verified from a review of all individual medical records.

MEASUREMENTS

Data were collected with respect to antipsychotic use, outcomes, and clinical features. Socio-demographic variables of DD cases were compared to a non-matched comparison group (n=278) and an age and gender matched comparison group with a 1:1 ratio (n=55).

RESULTS

The predominant type of DD was persecutory (87%). Non-prominent hallucinations were experienced by 18%, and depressive symptoms occurred in 22%. There was a statistically significant association between having DD and social isolation (χ2= 11.04 (DF=1) p<0.001; McNemar's test p<0.001). Atypical antipsychotic medication was prescribed in 32 cases, with follow-up permitted in 51 of the 55 cases (mean duration 36.6 months). Sustained recovery occurred in 20%, and improvement in an additional 35% of the study sample. Four patients subsequently developed dementia, and two developed mild cognitive impairment.

CONCLUSIONS

Clinical improvement, including sustained recovery, occurred in more than half of those with late life DD. The majority of those who improved (96%) received atypical antipsychotics.

Cognition and functionality in delusional disorder

Background:

Even if neurocognition is known to affect functional outcomes in schizophrenia, no previous study has explored the impact of cognition on functionality in delusional disorder (DD). We aimed to assess the effect of clinical characteristics, symptom dimensions and neuropsychological performance on psychosocial functioning and self-perceived functional impairment in DD.

Methods:

Seventy-five patients with a SCID-I confirmed diagnosis of DD underwent neurocognitive testing using a neuropsychological battery examining verbal memory, attention, working memory and executive functions. We assessed psychotic symptoms with the Positive and Negative Syndrome Scale, and calculated factor scores for four clinical dimensions: Paranoid, Cognitive, Affective and Schizoid. We conducted hierarchical linear regression models to identify predictors of psychosocial functioning, as measured with the Global Assessment of Functioning scale, and self-perceived functional impairment, as measured with the Sheehan’s Disability Inventory.

Results:

In the final linear regression models, higher scores in the Paranoid (β= 0.471, p <.001, r2 = 0.273) and Cognitive (β = 0.325, p <.001, r2 = 0.180) symptomatic dimensions and lower scores in verbal memory (β = −0.273, p <.05, r2 = 0.075) were significantly associated with poorer psychosocial functioning in patients with DD. Lower scores in verbal memory (β= −0.337, p <.01, r2 = 0.158) and executive functions (β= −0.323, p <.01, r2 = 0.094) were significantly associated with higher self-perceived disability.

Conclusions:

Impaired verbal memory and cognitive symptoms seem to affect functionality in DD, above and beyond the severity of the paranoid idea. This suggests a potential role for cognitive interventions in the management of DD.

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.

Poststroke psychosis: a systematic review

A preregistered systematic review of poststroke psychosis examining clinical characteristics, prevalence, diagnostic procedures, lesion location, treatments, risk factors and outcome. Neuropsychiatric outcomes following stroke are common and severely impact quality of life. No previous reviews have focused on poststroke psychosis despite clear clinical need. CINAHL, MEDLINE and PsychINFO were searched for studies on poststroke psychosis published between 1975 and 2016. Reviewers independently selected studies for inclusion, extracted data and rated study quality. Out of 2442 references, 76 met inclusion criteria. Average age for poststroke psychosis was 66.6 years with slightly more males than females affected. Delayed onset was common. Neurological presentation was typical for stroke, but a significant minority had otherwise 'silent strokes'. The most common psychosis was delusional disorder, followed by schizophrenia-like psychosis and mood disorder with psychotic features. Estimated delusion prevalence was 4.67% (95% CI 2.30% to 7.79%) and hallucinations 5.05% (95% CI 1.84% to 9.65%). Twelve-year incidence was 6.7%. No systematic treatment studies were found. Case studies frequently report symptom remission after antipsychotics, but serious concerns about under-representation of poor outcome remain. Lesions were typically right hemisphere, particularly frontal, temporal and parietal regions, and the right caudate nucleus. In general, poststroke psychosis was associated with poor functional outcomes and high mortality. Poor methodological quality of studies was a significant limitation. Psychosis considerably adds to illness burden of stroke. Delayed onset suggests a window for early intervention. Studies on the safety and efficacy of antipsychotics in this population are urgently needed.

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.

A dimensional comparison between delusional disorder, schizophrenia and schizoaffective disorder

INTRODUCTION

Since the early description of paranoia, the nosology of delusional disorder has always been controversial. The old idea of unitary psychosis has now gained some renewed value from the dimensional continuum model of psychotic symptoms.

AIMS

1. To study the psychopathological dimensions of the psychosis spectrum; 2. to explore the association between psychotic dimensions and categorical diagnoses; 3. to compare the different psychotic disorders from a psychopathological and functional point of view.

MATERIAL AND METHODS

This is an observational study utilizing a sample of some 550 patients with a psychotic disorder. 373 participants had a diagnosis of schizophrenia, 137 had delusional disorder and 40 with a diagnosis of schizoaffective disorder. The PANSS was used to elicit psychopathology and global functioning was ascertained using the GAF measure. Both exploratory and confirmatory factor analyses of the PANSS items were performed to extract psychopathological dimensions. Associations between diagnostic categories and dimensions were subsequently studied using ANOVA tests.

RESULTS

5 dimensions - manic, negative symptoms, depression, positive symptoms and cognitive - emerged. The model explained 57.27% of the total variance. The dimensional model was useful to explained differences and similarities between all three psychosis spectrum categories. The potential clinical usefulness of this dimensional model within and between clinical psychosis spectrum categories is discussed.

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

BACKGROUND

Delusional disorder (DD) is thought to be distinct from schizophrenia (SZ). However, few systematic investigations have been conducted on DD because of the difficulty in ascertaining a representative sample size. Existing knowledge has been mostly generated from inpatient cohorts, which may be biased towards a more severe sample.

METHOD

We compared the demographic, clinical and cognitive differences between 71 patients with first-episode DD and 71 age-matched patients with first-episode SZ. Participants were consecutively recruited from a population-based territory-wide study of early psychosis in Hong Kong targeting first-episode psychosis. Basic demographic information, premorbid functioning, duration of untreated psychosis, pathways to care, symptomatology, social, occupational, and cognitive functioning were comprehensively assessed using standardized measurements.

RESULTS

Patients with DD had less premorbid schizoid and schizotypal traits compared to patients with SZ. More patients with DD were married compared to patients with SZ. However, at first episode, there were no significant differences between the two groups in regards to the duration of untreated psychosis, pathways to care, symptom severity, neurocognitive performance, treatment, and functioning.

CONCLUSIONS

Our findings challenge previous thinking that patients with DD had better functioning than patients with SZ. This study not only provides an updated perspective into conceptualizing the clinical differences between DD and SZ, but also expands the descriptive account of the two disorders to include the neurocognitive dimension.

The development of delusion revisited: a transdiagnostic framework

This study proposes a transdiagnostic framework for delusion development, analysing psychiatric (schizophrenia, bipolar disorder, major depressive disorder) and neurological disorders (stroke, and neurodegenerative diseases) in which delusions are predominant. Our aim is to identify a transdiagnostic core of neural and cognitive alterations associated with delusions across distinct clinical disorders. Reviewed empirical evidence suggests delusions are associated: on the neural level with changes in the ventromedial prefrontal cortex (vmPFC) networks, and on the neuropsychological level with dysfunction in the processes (generation of affective value, the construction of internal models of the world, and the reflection about Self and/or Other's mental states) that these network mediate. The concurrent aberration of all these processes could be critical for the clinical transition to a psychotic delusional state. In particular, delusions could become clinically manifest when (1) stimuli are attributed an aberrant affective salience, that (2) is explained by the patient within distorted explanatory internal models that (3) are poorly inhibited by cognitive control systems. This framework extends the two-factor account of delusion model and suggests that common neural mechanisms for the delusions in psychiatric and in neurological disorders.

Delusional disorder and oncology: review of the literature and case report

OBJECTIVE

Delusional disorder is an infrequent diagnosis in outpatient clinical practice. While delusional thought processes are a fairly common part of symptom clusters in chronic psychiatric disorders such as schizophrenia and bipolar disorders, true delusional disorders are believed to be fairly rare.

METHOD

In this article, we review scientific data on incidence, diagnosis, and treatment of delusional disorders. This was done by PubMed search utilizing the search terms "delusional disorder," "oncology," "diagnosis," and "treatment." Relevant articles were excluded if they dealt predominantly with schizophrenia instead of primary delusional disorder.

RESULTS

We present a case of a patient diagnosed with follicular lymphoma and an apparent longstanding history of persecutory delusions. The patient's symptoms eventually led to intervention in the oncology practice involving the medical center faculty and staff, as well as local police and the court system.

CONCLUSIONS

Delusional disorder is an under-researched condition, and limited information is known regarding the treatment of this condition when it impacts upon medical care. Future research directions are proposed.

Deficits in executive and memory processes in delusional disorder: a case-control study

OBJECTIVE

Delusional disorder has been traditionally considered a psychotic syndrome that does not evolve to cognitive deterioration. However, to date, very little empirical research has been done to explore cognitive executive components and memory processes in Delusional Disorder patients. This study will investigate whether patients with delusional disorder are intact in both executive function components (such as flexibility, impulsivity and updating components) and memory processes (such as immediate, short term and long term recall, learning and recognition).

METHODS

A large sample of patients with delusional disorder (n = 86) and a group of healthy controls (n = 343) were compared with regard to their performance in a broad battery of neuropsychological tests including Trail Making Test, Wisconsin Card Sorting Test, Colour-Word Stroop Test, and Complutense Verbal Learning Test (TAVEC).

RESULTS

When compared to controls, cases of delusional disorder showed a significantly poorer performance in most cognitive tests. Thus, we demonstrate deficits in flexibility, impulsivity and updating components of executive functions as well as in memory processes. These findings held significant after taking into account sex, age, educational level and premorbid IQ.

CONCLUSIONS

Our results do not support the traditional notion of patients with delusional disorder being cognitively intact.

Empirical redefinition of delusional disorder and its phenomenology: the DELIREMP study

AIMS

Since Kraepelin, the controversy has persisted surrounding the nature of delusional disorder (DD) as a separate nosological entity or its clinical subtypes. Nevertheless, there has been no systematic study of its psychopathological structure based on patient interviews. Our goal was to empirically explore syndromic subentities in DD.

METHODS

A cross-sectional study was conducted in 86 outpatients with DSM-IV-confirmed DD using SCID-I. Psychopathological factors were identified by factor analysis of PANSS scores. The association between these factors and clinical variables (as per standardized instruments) was analyzed using uni- and multivariate techniques.

RESULTS

PANSS symptoms were consistent with four factors (Paranoid, Cognitive, Schizoid, and Affective dimensions), accounting for 59.4% of the total variance. The Paranoid Dimension was associated with premorbid paranoid personality disorder, more adverse childhood experiences, chronic course, legal problems, worse global functioning, and poorer treatment adherence and response. The Cognitive Dimension was associated with poorer cognitive functioning, premorbid substance abuse, comorbid somatic diseases, mainly non-prominent visual hallucinations, fewer comorbid depressive disorders, and poorer global functioning. The Schizoid Dimension was associated with being single, a family history of schizophrenia, premorbid personality disorders (largely schizoid and schizotypal), non-prominent auditory hallucinations, and dysthymia. Finally, the Affective Dimension was associated with a family history of depression, premorbid obsessive personality, somatic delusions, absence of reference delusions, tactile and olfactory hallucinations, depressive and anxiety disorders, risk of suicide, and higher perceived stress.

CONCLUSION

The identification and clinical validation of four separate psychopathological dimensions in DD provide evidence toward a more accurate conceptualization of DD and its types.

Classifying psychosis--challenges and opportunities

Within the efforts to revise ICD-10 and DSM-IV-TR, work groups on the classification of psychotic disorders appointed by the World Health Organization (WHO) and the American Psychiatric Association (APA) have proposed several changes to the corresponding classification criteria of schizophrenia and other psychotic disorders in order to increase the clinical utility, reliability and validity of these diagnoses. These proposed revisions are subject to field trials with the objective of studying whether they will lead to an improvement of the classification systems in comparison to their previous versions. Both a challenge and an opportunity, the APA and WHO have also considered harmonizing between the two classifications. The current status of both suggests that this goal can only be met in part. The main proposed revisions include changes to the number and types of symptoms of schizophrenia, the replacement of existing schizophrenia subtypes with dimensional assessments or symptom specifiers, different modifications of the criteria for schizoaffective disorder, a reorganization of the delusional disorders and the acute and transient psychotic disorders in ICD-11, as well as the revision of course and psychomotor symptoms/catatonia specifiers in both classification systems.