Structural and functional brain changes in delusional disorder

Structural and functional alterations in different types of delusions across schizophrenia spectrum: A systematic review

BACKGROUND

Despite the high clinical role of delusions as a transnosological psychopathological phenomenon, the number of experimental studies on the different types of delusions across schizophrenia spectrum is still relatively small, and their results are somehow inconsistent. We aimed to understand the current state of knowledge regarding the structural and functional brain alterations in delusions to determine whether particular types of delusions are associated with specific brain changes and to identify common alterations underlying the formation and persistence of delusions regardless of their content.

METHODS

For this systematic review, we followed PRISMA guidelines to search in PubMed for English papers published between 1953 and September 30, 2023. The initial inclusion criteria for screening purposes were articles that investigated delusions or subclinical delusional beliefs in schizophrenia spectrum disorders, high clinical or genetic risk for schizophrenia using fMRI, sMRI or/and dwMRI methods. Exclusion criteria during the screening phase were articles that investigated lesion-induced or substance-induced delusions, delusions in Alzheimer's disease and other neurocognitive disorders, single case studies and non-human studies. The publication metadata were uploaded to the web-tool for working on systematic reviews, Rayyan. For each of the studies, a table was filled out with detailed information.

RESULTS

We found 1752 records, of which 95 full-text documents were reviewed and included in the current paper. Both nonspecific and particular types of delusions were associated with widespread structural and functional alterations. The most prominent areas affected across all types of delusions were the superior temporal cortex (predominantly left language processing areas), anterior cingulate/medial prefrontal cortex and insula. The most reproducible findings in paranoia may be alterations in the functioning of the amygdala and its interactions with other regions. Somatic delusions and delusional infestation were mostly characterized by alterations in the insula and thalamus.

DISCUSSION

The data are ambiguous; however, in general the predictive processing framework seems to be the most widely accepted approach to explaining different types of delusions. Aberrant prediction errors signaling during processing of social, self-generated and sensory information may lead to inaccuracies in assessing the intentions of others, self-relevancy of ambiguous stimuli, misattribution of self-generated actions and unusual sensations, which could provoke delusional ideation with persecutory, reference, control and somatic content correspondingly. However, currently available data are still insufficient to draw conclusions about the specific biological mechanisms of predictive coding account of delusions. Thus, further studies exploring more homogeneous groups and interaction of diagnoses by types of delusions are needed. There are also some limitations in this review. Studies that investigate delusions induced by lesions, substance abuse or neurodegeneration and studies using modalities other than fMRI, sMRI or dwMRI were not included in the review. Due to the relatively small number of publications, we systematized them based on a certain type of delusions, while the results could also be affected by the diagnosis of patients, the presence and type of therapy, illness duration etc.

A working model of neural activity and phenomenal experience in psychosis

According to classical phenomenology, phenomenal experience is composed of perceptions (related to environmental stimuli) and imagery/ideas (unrelated to environmental stimuli). Intensity/vividness is supposed to represent the key phenomenal difference between perceptions and ideas, higher in perceptions than ideas, and thus the core subjective criterion to distinguish reality from imagination. At a neural level, phenomenal experience is related to brain activity in the sensory areas, driven by receptor stimulation (underlying perception) or associative areas (underlying imagery/ideas). An alteration of the phenomenal experience that leads to a loss of contact with reality characterizes psychosis, which mainly consists of hallucinations (false perceptions) and delusions (fixed ideas). According to the current data on their neural correlates across subclinical conditions and different neuropsychiatric disorders (such as schizophrenia), hallucinations are mainly associated with: transient (modality-specific) activations of sensory cortices (primarily superior temporal gyrus, occipito-temporal cortex, postcentral gyrus, and insula) during the hallucinatory experience; increased intrinsic activity/connectivity of associative/default-mode network (DMN) areas (primarily temporoparietal junction, posterior cingulate cortex, and medial prefrontal cortex); and deficits in the sensory systems. Analogously, delusions are mainly associated with increased intrinsic activity/connectivity of associative/DMN areas (primarily medial prefrontal cortex). Integrating these data into our three-dimensional model of neural activity and phenomenal-behavioral patterns, we propose the following model of psychosis. A functional/structural deficit in the sensory systems complemented by a functional reconfiguration of intrinsic brain activity favoring hyperactivity of associative/DMN areas may drive neuronal activations in the sensory (auditory/visual/somatosensory) areas and insular (interoceptive) areas with spatiotemporal configurations maximally independent from environmental stimuli and predominantly related to associative processing. This manifests in perception deficit and imagery/ideas composed of exteroceptive-like and interoceptive/affective-like elements that show a phenomenal intensity indistinguishable from perceptions, impairing the reality monitoring, along with minimal changeability by environmental stimuli, ultimately resulting in dissociation of the phenomenal experience from the environment, i.e., psychosis.

Changes in hoarding-related beliefs and associated neural changes during a simulated discarding task after cognitive-behavioral treatment for hoarding disorder

Hoarding disorder (HD) is maintained by maladaptive beliefs about possessions, and recent research has demonstrated that changes in these beliefs partially mediate improvement in cognitive-behavioral therapy (CBT) for hoarding. It is not yet known whether changes in neural activity, particularly when discarding possessions, are associated with cognitive change during CBT for HD. Adults who completed group CBT for HD (N = 58) participated in a simulated discarding task before and after CBT. Neural activity was measured using functional magnetic resonance imaging (fMRI) as participants made simulated discarding decisions. At baseline, activity in the left middle insula and left anterior cingulate cortex was significantly associated with hoarding-related beliefs. After receiving CBT for HD, decreases in maladaptive hoarding-related beliefs were significantly associated with increased activity compared to baseline in the right anterior ventral insula, along the left middle frontal gyrus and bilateral inferior temporal lobe, and in visuospatial areas. These results demonstrate that maladaptive beliefs in HD are associated with activation of specific neural regions during discarding decisions and that reduction in beliefs over a course of CBT for HD is associated with specific changes in neural activity.

Disentangling the role of gray matter volume and concentration in autism spectrum disorder: A meta-analytic investigation of 25 years of voxel-based morphometry research

Despite over two decades of neuroimaging research, a unanimous definition of the pattern of structural variation associated with autism spectrum disorder (ASD) has yet to be found. One potential impeding issue could be the sometimes ambiguous use of measurements of variations in gray matter volume (GMV) or gray matter concentration (GMC). In fact, while both can be calculated using voxel-based morphometry analysis, these may reflect different underlying pathological mechanisms. We conducted a coordinate-based meta-analysis, keeping apart GMV and GMC studies of subjects with ASD. Results showed distinct and non-overlapping patterns for the two measures. GMV decreases were evident in the cerebellum, while GMC decreases were mainly found in the temporal and frontal regions. GMV increases were found in the parietal, temporal, and frontal brain regions, while GMC increases were observed in the anterior cingulate cortex and middle frontal gyrus. Age-stratified analyses suggested that such variations are dynamic across the ASD lifespan. The present findings emphasize the importance of considering GMV and GMC as distinct yet synergistic indices in autism research.

Statistical shape analysis of corpus callosum in delusional disorder

Neurobiological foundations of delusional disorder (DD) have been studied less with neuroimaging techniques when compared to other psychotic disorders. The present study aimed to delineate the neural substrates of DD by investigating neuroanatomical characteristics of the corpus callosum (CC) with statistical shape analysis (SSA) conducted on magnetic resonance images (MRI). Twenty (female:male=1:1) DSM-5 DD patients and 20 age- and gender-matched healthy individuals were included. High-resolution 3D T1 Turbo Field Echo MRI images were scanned with a 1.5 T MR device. The landmarks that were selected to determine the shape differences in CC were identified based on previous studies. Furthermore, constructed landmarks were determined and employed to better assess regional shape differences. There was no significant difference in the CC area in the mid-sagittal images between the DD patients and controls. However, DD patients exhibited a pattern of structural CC changes in various regions. The study findings emphasizes the variable subregional nature of CC in DD patients. Future SSA studies with larger samples could shed further light on DD etiology, diagnosis, classification and treatment options.

Connectome-based predictive modeling predicts paranoid ideation in young men with paranoid personality disorder: a resting-state functional magnetic resonance imaging study

Paranoid personality disorder (PPD), a mental disorder that affects interpersonal relationships and work, is frequently neglected during diagnosis and evaluation at the individual-level. This preliminary study aimed to investigate whether connectome-based predictive modeling (CPM) can predict paranoia scores of young men with PPD using whole-brain resting-state functional connectivity (rs-FC). College students with paranoid tendencies were screened using paranoia scores ≥60 derived from the Minnesota Multiphasic Personality Inventory; 18 participants were ultimately diagnosed with PPD according to the Diagnostic and Statistical Manual of Mental Disorders and subsequently underwent resting-state functional magnetic resonance imaging. Whole-brain rs-FC was constructed, and the ability of this rs-FC to predict paranoia scores was evaluated using CPM. The significance of the models was assessed using permutation tests. The model constructed based on the negative prediction network involving the limbic system-temporal lobe was observed to have significant predictive ability for paranoia scores, whereas the model constructed using the positive and combined prediction network had no significant predictive ability. In conclusion, using CPM, whole-brain rs-FC predicted the paranoia score of patients with PPD. The limbic system-temporal lobe FC pattern is expected to become an important neurological marker for evaluating paranoid ideation.

Differences between delusional disorder and schizophrenia: A mini narrative review

Psychotic syndromes are divided into affective and non-affective forms. Even among the non-affective forms, substantial differences exist. The aim of this relatively brief review is to synthesize what is known about the differences between two non-affective psychoses, schizophrenia and delusional disorder (DD), with respect to clinical, epidemiological, sociodemographic, and treatment response characteristics. A PubMed literature search revealed the following: in schizophrenia, hallucinations, negative symptoms and cognitive symptoms are prominent. They are rare in DD. Compared to schizophrenia patients, individuals with DD maintain relatively good function, and their delusions are believable; many are beliefs that are widely held in the general population. Treatments are generally similar in these two forms of psychosis, with the exception that antidepressants are used more frequently in DD and, for acute treatment, effective antipsychotic doses are lower in DD than in schizophrenia. It is with the hope that the contrasts between these two conditions will aid in the provision of safe and effective treatment for both that this review has been conducted.

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.

Care for Women with Delusional Disorder: Towards a Specialized Approach

Delusional disorder is a difficult-to-treat clinical condition with health needs that are often undertreated. Although individuals with delusional disorder may be high functioning in daily life, they suffer from serious health complaints that may be sex-specific. The main aim of this narrative review is to address these sex-specific health needs and to find ways of integrating their management into service programs. Age is an important issue. Delusional disorder most often first occurs in middle to late adult life, a time that corresponds to menopause in women, and menopausal age correlates with increased development of both somatic and psychological health problems in women. It is associated with a rise in the prevalence of depression and a worsening of prior psychotic symptoms. Importantly, women with delusional disorder show low compliance rates with both psychiatric treatment and with medical/surgical referrals. Intervention at the patient, provider, and systems levels are needed to address these ongoing problems.

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.

An overlapping pattern of cerebral cortical thinning is associated with both positive symptoms and aggression in schizophrenia via the ENIGMA consortium

BACKGROUND

Positive symptoms are a useful predictor of aggression in schizophrenia. Although a similar pattern of abnormal brain structures related to both positive symptoms and aggression has been reported, this observation has not yet been confirmed in a single sample.

METHOD

To study the association between positive symptoms and aggression in schizophrenia on a neurobiological level, a prospective meta-analytic approach was employed to analyze harmonized structural neuroimaging data from 10 research centers worldwide. We analyzed brain MRI scans from 902 individuals with a primary diagnosis of schizophrenia and 952 healthy controls.

RESULTS

The result identified a widespread cortical thickness reduction in schizophrenia compared to their controls. Two separate meta-regression analyses revealed that a common pattern of reduced cortical gray matter thickness within the left lateral temporal lobe and right midcingulate cortex was significantly associated with both positive symptoms and aggression.

CONCLUSION

These findings suggested that positive symptoms such as formal thought disorder and auditory misperception, combined with cognitive impairments reflecting difficulties in deploying an adaptive control toward perceived threats, could escalate the likelihood of aggression in schizophrenia.

Validity and utility of Hierarchical Taxonomy of Psychopathology (HiTOP): I. Psychosis superspectrum

The Hierarchical Taxonomy of Psychopathology (HiTOP) is a scientific effort to address shortcomings of traditional mental disorder diagnoses, which suffer from arbitrary boundaries between psychopathology and normality, frequent disorder co-occurrence, heterogeneity within disorders, and diagnostic instability. This paper synthesizes evidence on the validity and utility of the thought disorder and detachment spectra of HiTOP. These spectra are composed of symptoms and maladaptive traits currently subsumed within schizophrenia, other psychotic disorders, and schizotypal, paranoid and schizoid personality disorders. Thought disorder ranges from normal reality testing, to maladaptive trait psychoticism, to hallucinations and delusions. Detachment ranges from introversion, to maladaptive detachment, to blunted affect and avolition. Extensive evidence supports the validity of thought disorder and detachment spectra, as each spectrum reflects common genetics, environmental risk factors, childhood antecedents, cognitive abnormalities, neural alterations, biomarkers, and treatment response. Some of these characteristics are specific to one spectrum and others are shared, suggesting the existence of an overarching psychosis superspectrum. Further research is needed to extend this model, such as clarifying whether mania and dissociation belong to thought disorder, and explicating processes that drive development of the spectra and their subdimensions. Compared to traditional diagnoses, the thought disorder and detachment spectra demonstrated substantially improved utility: greater reliability, larger explanatory and predictive power, and higher acceptability to clinicians. Validated measures are available to implement the system in practice. The more informative, reliable and valid characterization of psychosis-related psychopathology offered by HiTOP can make diagnosis more useful for research and clinical care.

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.

Abnormal cerebellar volume in somatic vs. non-somatic delusional disorders

Background

There is abundant evidence for cerebellar involvement in schizophrenia, where the cerebellum has been suggested to contribute to cognitive, affective and motor dysfunction. More recently, specific cerebellar regions have also been associated with psychotic symptoms, particularly with auditory verbal hallucinations. In contrast, little is known about cerebellar contributions to delusions, and even less is known about whether cerebellar involvement differs by delusional content.

Methods

Using structural magnetic resonance imaging at 1.0 T together with cerebellum-optimized segmentation techniques, we investigated gray matter volume (GMV) in 14 patients with somatic-type delusional disorder (S-DD), 18 patients with non-somatic delusional disorder (NS-DD) and 18 patients with schizophrenia (SZ) with persistent non-somatic delusions. A total of 32 healthy controls (HC) were included. Between-group comparisons were adjusted for age, gender, chlorpromazine equivalents and illness duration.

Results

Compared to HC, S-DD patients showed decreased GMV in left lobule VIIIa. In addition, S-DD patients showed decreased GMV in lobule V and increased GMV in bilateral lobule VIIa/crus II compared to NS-DD. Patients with SZ showed increased GMV in right lobule VI and VIIa/crus I compared to HC. Significant differences between HC and NS-DD were not found.

Conclusions

The data support the notion of cerebellar dysfunction in psychotic disorders. Distinct cerebellar deficits, predominantly linked to sensorimotor processing, may be detected in delusional disorders presenting with predominantly somatic content.

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.

Activation of the motivation-related ventral striatum during delusional experience

Delusion is the most characteristic symptom of psychosis, occurring in almost all first-episode psychosis patients. The motivational salience hypothesis suggests delusion to originate from the experience of abnormal motivational salience. Whether the motivation-related brain circuitries are activated during the actual delusional experience remains, however, unknown. We used a forced-choice answering tree at random intervals during functional magnetic resonance imaging to capture delusional and non-delusional spontaneous experiences in patients with first-episode psychosis (n = 31) or clinical high-risk state (n = 7). The motivation-related brain regions were identified by an automated meta-analysis of 149 studies. Thirteen first-episode patients reported both delusional and non-delusional spontaneous experiences. In these patients, delusional experiences were related to stronger activation of the ventral striatum in both hemispheres. This activation overlapped with the most strongly motivation-related brain regions. These findings provide an empirical link between the actual delusional experience and the motivational salience hypothesis. Further use and development of the present methods in localizing the neurobiological basis of the most characteristic symptoms may be useful in the search for etiopathogenic pathways that result in psychotic disorders.

Voxel-based meta-analysis via permutation of subject images (PSI): Theory and implementation for SDM

Coordinate-based meta-analyses (CBMA) are very useful for summarizing the large number of voxel-based neuroimaging studies of normal brain functions and brain abnormalities in neuropsychiatric disorders. However, current CBMA methods do not conduct common voxelwise tests, but rather a test of convergence, which relies on some spatial assumptions that data may seldom meet, and has lower statistical power when there are multiple effects. Here we present a new algorithm that can use standard voxelwise tests and, importantly, conducts a standard permutation of subject images (PSI). Its main steps are: a) multiple imputation of study images; b) imputation of subject images; and c) subject-based permutation test to control the familywise error rate (FWER). The PSI algorithm is general and we believe that developers might implement it for several CBMA methods. We present here an implementation of PSI for seed-based d mapping (SDM) method, which additionally benefits from the use of effect sizes, random-effects models, Freedman-Lane-based permutations and threshold-free cluster enhancement (TFCE) statistics, among others. Finally, we also provide an empirical validation of the control of the FWER in SDM-PSI, which showed that it might be too conservative. We hope that the neuroimaging meta-analytic community will welcome this new algorithm and method.

Correlation Between Levels of Delusional Beliefs and Perfusion of the Hippocampus and an Associated Network in a Non-Help-Seeking Population

BACKGROUND

Delusions are a defining and common symptom of psychotic disorders. Recent evidence suggests that subclinical and clinical delusions may represent distinct stages on a phenomenological and biological continuum. However, few studies have tested whether subclinical psychotic experiences are associated with neural changes that are similar to those observed in clinical psychosis. For example, it is unclear if overactivity of the hippocampus, a replicated finding of neuroimaging studies of schizophrenia, is also present in individuals with subclinical psychotic symptoms.

METHODS

To investigate this question, structural and pulsed arterial spin labeling scans were collected in 77 adult participants with no psychiatric history. An anatomical region of interest approach was used to extract resting perfusion of the hippocampus, and 15 other regions, from each individual. A self-report measure of delusional ideation was collected on the day of scanning.

RESULTS

The level of delusional thinking (number of beliefs [r = .27, p = .02]), as well as the associated level of distress (r = .29, p = .02), was significantly correlated with hippocampal perfusion (averaged over right and left hemispheres). The correlations remained significant after controlling for age, hippocampal volume, symptoms of depression and anxiety, and image signal-to-noise ratio, and they were confirmed in a voxelwise regression analysis. The same association was observed in the thalamus and parahippocampal, lateral temporal, and cingulate cortices.

CONCLUSIONS

Similar to patients with schizophrenia, non-help-seeking individuals show elevated perfusion of a network of limbic regions in association with delusional beliefs.

Regional gray matter volume and structural network strength in somatic vs. non-somatic delusional disorders

BACKGROUND

Monothematic delusional disorders are characterized by a single tenacious belief. They provide a great opportunity to study underlying brain structures in the absence of confounding symptoms that accompany delusions in schizophrenia. Delusional beliefs include persecution, jealousy or somatic delusions including infestation. It is unclear whether specific delusional content is associated with distinct neural substrates.

METHODS

We used magnetic resonance imaging in patients presenting with somatic vs. non-somatic delusional disorders. Patients with delusional infestation (DI, n=18), and individuals with non-somatic delusional disorders (n=19) were included, together with healthy volunteers (n=20). Uni- and multivariate techniques for structural data analysis were applied to provide a comprehensive characterization of abnormal brain volume at both the regional and neural network level.

RESULTS

Patients with DI showed lower gray matter volume in thalamic, striatal (putamen), insular and medial prefrontal brain regions in contrast to non-somatic delusional disorders and healthy controls. Importantly, these differences were consistently detected at regional and network level. Compared to healthy controls, patients with delusional disorders other than DI showed lower gray matter volume in temporal cortical regions.

CONCLUSION

The data support the notion that dysfunctional somatosensory and peripersonal networks could mediate somatic delusions in patients with DI in contrast to delusional disorders without somatic content. The data also suggest putative content-specific neural signatures in delusional disorders and in delusion formation per se.

Developmental Aspects of Schizotypy and Suspiciousness: a Review

Purpose of the Review

This review identifies the early developmental processes that contribute to schizotypy and suspiciousness in adolescence and adulthood. It includes the most recent literature on these phenomena in childhood.

Recent Findings

The early developmental processes that affect schizotypy and paranoia in later life are complex. In contrast to existing studies of psychiatric patients and clinical/nonclinical adult populations, the study of schizotypy and suspiciousness in young children and adolescents is possible due to new child-appropriate dimensional assessments. New assessments and the advancement of technology (e.g., virtual reality in mental health) as well as statistical modeling (e.g., mediation and latent-class analyses) in large data have helped identified the developmental aspects (e.g., psychosocial, neurocognitive and brain factors, nutrition, and childhood correlates) that predict schizotypy and suspiciousness in later life.

Summary

Prospective longitudinal designs in community youths can enhance our understanding of the etiology of schizophrenia-spectrum disorders and, in the future, the development of preventive interventions by extending adult theories and interventions to younger populations.

Demographic and clinical characteristics of diagnosed and non-diagnosed psychotic disorders in the community

AIM

Retrospective studies of first-episode psychosis patients have reported that psychosis often remains untreated for some time. Yet, from clinical samples, the characteristics and number of non-diagnosed untreated psychosis patients in a community can only be estimated. Thus, this short report compares socio-demographic and clinical features of diagnosed and non-diagnosed psychotic individuals assessed in the community.

METHODS

Using telephone interviews, we clinically assessed 2682 community participants (aged 16-40 years) in the Canton of Bern, Switzerland, to examine the characteristics of non-diagnosed psychosis.

RESULTS

Of the 41 detected psychosis patients (1.5% of the sample), 21 (54%) had already been diagnosed and treated. Non-diagnosed individuals experienced a delusional disorder (DD) (n = 10) more frequently than diagnosed individuals (n = 1), but did not differ in other socio-demographic characteristics.

CONCLUSION

Further study of DD should be emphasized, along with increased awareness of the condition in primary healthcare services, as individuals with DD might present themselves for other complaints.

Risperidone versus olanzapine in the acute treatment of Persistent Delusional Disorder: A retrospective analysis

There is a dearth of prospective trials studying treatment response in Persistent Delusional Disorder (PDD) to guide clinical practice. Available retrospective data indicate good response to second-generation antipsychotics (SGAs). We selected the data of patients prescribed either olanzapine or risperidone from a retrospective chart review of PDD (n=455) at our centre. We compared the two groups olanzapine (n =86) versus risperidone (n =280) on dose, drug adherence, response and adverse effects. The two groups were comparable on socio-demographic and clinical characteristics of PDD. There was no statistically significant difference between the two groups on adherence (>80%) and response to treatment (>52% good response). Olanzapine was effective at lower mean chlorpromazine equivalents than risperidone. Logistic regression analysis identified shorter mean duration of illness, good adherence and absence of substance dependence as predictors of good response to both drugs. Our study indicates that acute PDD responds well to treatment with both risperidone and olanzapine, provided adherence can be ensured. In the absence of specific treatment guidelines and randomized controlled trials for PDD, our analysis reaffirms the efficacy of SGAs.

Midline Brain Abnormalities Across Psychotic and Mood Disorders

Patients with schizophrenia are known to have increased prevalence of abnormalities in midline brain structures, such as a failure of the septum pellucidum to fuse (cavum septum pellucidum) and the absence of the adhesio interthalamica. This is the first study to investigate the prevalence of these abnormalities across a large multidiagnostic sample. Presence of cavum septum pellucidum and absence of the adhesio interthalamica was assessed in 639 patients with chronic schizophrenia, delusional disorder, schizoaffective disorder, bipolar disorder, major depressive disorder, or a first episode of psychosis, mania or unipolar depression. This was compared with 223 healthy controls using logistic-regression-derived odds ratios (OR). Patients with psychotic or mood disorders showed an increased prevalence of both abnormalities (OR of cavum septum pellucidum = 2.1, OR of absence of the adhesio interthalamica = 2.6, OR of both cavum septum pellucidum and absence of the adhesio interthalamica = 3.8, all P < .001). This increased prevalence was separately observed in nearly all disorders as well as after controlling for potential confounding factors. This study supports a general increased prevalence of midline brain abnormalities across mood and psychotic disorders. This nonspecificity may suggest that these disorders share a common neurodevelopmental etiology.