Genetics and delusional disorder

Delusional Disorder in Old Age: A Hypothesis-Driven Review of Recent Work Focusing on Epidemiology, Clinical Aspects, and Outcomes

The theme, strength, and duration of a delusion are considered important in distinguishing one psychosis of old age from another. Research results, however, are mostly based on studies conducted on one form of psychosis, namely schizophrenia. The aim of this hypothesis-driven narrative review is to gather clinically important information about the psychosis identified as delusional disorder (DD), as it affects persons of senior age. We hypothesized that DD becomes relatively prevalent in old age, especially in women; and that it is associated with demonstrable brain changes, which, in turn, are associated with cognitive defects and poor pharmacological response, thus increasing the risk of aggression and suicide. Computerized searches in PubMed and ClinicalTrials.gov were conducted using the following search terms: (delusional disorder) AND (elderly OR old OR aged OR psychogeriatrics). A total of 16 recent studies (including case reports) were reviewed. Our hypotheses could not be definitively confirmed because research evidence is lacking. In order to improve eventual outcomes, our literature search demonstrates the need for more targeted, well-designed studies.

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.

Genetic relationships between schizophrenia, bipolar disorder, and schizoaffective disorder

There is substantial evidence for partial overlap of genetic influences on schizophrenia and bipolar disorder, with family, twin, and adoption studies showing a genetic correlation between the disorders of around 0.6. Results of genome-wide association studies are consistent with commonly occurring genetic risk variants, contributing to both the shared and nonshared aspects, while studies of large, rare chromosomal structural variants, particularly copy number variants, show a stronger influence on schizophrenia than bipolar disorder to date. Schizoaffective disorder has been less investigated but shows substantial familial overlap with both schizophrenia and bipolar disorder. A twin analysis is consistent with genetic influences on schizoaffective episodes being entirely shared with genetic influences on schizophrenic and manic episodes, while association studies suggest the possibility of some relatively specific genetic influences on broadly defined schizoaffective disorder, bipolar subtype. Further insights into genetic relationships between these disorders are expected as studies continue to increase in sample size and in technical and analytical sophistication, information on phenotypes beyond clinical diagnoses are increasingly incorporated, and approaches such as next-generation sequencing identify additional types of genetic risk variant.

Delusional disorders--are they simply paranoid schizophrenia?

OBJECTIVES

This article tries to give an answer to the question of whether International Classification of Diseases (ICD-10) persistent delusional disorder (PDD) or Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) delusional disorder (DD) is simply paranoid schizophrenia (PS). Because ICD-10 PDD and DSM-IV DD are identical, we use DD as a synonym.

METHODS

A prospective and longitudinal study compared all inpatients with DD treated at the Halle-Wittenberg university hospital during a 14-year period with a previously investigated selected cohort of patients with PS. Sociodemographic data, symptomatology, course, and outcome parameters were examined using standardized instruments. The duration of the follow-up period in patients with DD was 10.8 years and for the PS patients 12.9 years.

RESULTS

Significant differences between DD and PS were found: DD patients are, in comparison to patients with PS, significantly older at onset. Less of their first-degree relatives have mental disorders. They less frequently come from a broken home situation. First-rank symptoms, relevant negative symptoms, and primary hallucinations did not occur in patients with DD. Patients with DD were less frequently hospitalized, and the duration of their hospitalization was shorter. Their outcome is much better regarding employment, early retirement due to the disorder, and psychopharmacological medication. They more often had stable heterosexual partnerships and were autarkic. They had lower scores in the Disability Assessment Scale and in Positive and Negative Syndrome Scale. The diagnosis of DD is very stable over time.

CONCLUSIONS

The findings of this study support the assumption that DDs are a separate entity and only exceptionally can be a prodrome of schizophrenia.

A general neuropsychological model of delusion

INTRODUCTION

Neurocognitive accounts of delusion have traditionally highlighted perceptual misrepresentation, as the primary trigger in addition to other cognitive deficits that maintain the delusion. Here, a general neurocognitive model of delusional disorder (DSM-IV) is proposed, not so much based on perceptual or cognitive deficits after right hemisphere damage as on cognitive propensities, specifically excessive inferencing (especially jumping to conclusions) and excessive reference to the self, due to left hemisphere overactivity.

METHOD

The functional imaging, topographic EEG, and experimental imaging literatures on delusional disorder are reviewed, and 37 previously published cases of postunilateral lesion delusion (DSM-IV type, grandeur, persecution, jealousy, erotomania, or somatic), are reviewed and analysed multivariately.

RESULTS

Functional imaging and EEG topography data were slightly more indicative of left hemisphere overactivity in delusional disorder. In addition, 73% of the postunilateral lesion cases (χ(2)=7.8, p=.005) of delusional disorder (DSM-IV type) had a right hemisphere lesion, whereas only 27% had a left hemisphere lesion.

CONCLUSION

Left hemisphere release appears to be a more primary cause of delusional disorder than right hemisphere impairment, the latter merely entailing loss of inhibition of delusional beliefs. We propose that most patients with DSM-IV diagnoses of delusional disorder could be afflicted by excessive left hemisphere activity, but further research is necessary.

Heritability estimates for psychotic symptom dimensions in twins with psychotic disorders

Factor analysis of psychotic symptoms frequently results in positive, negative, and disorganized dimensions, but heritability estimates have not yet been reported. Symptom dimensions are usually only measured in individuals with psychotic disorders. Here, it is valuable to assess influences acting via liability to psychosis and independent modifying effects. We estimated heritability for psychotic symptom dimensions, taking account of these issues. Two-hundred-and-twenty-four probandwise twin pairs (106 monozygotic, 118 same-sex dizygotic), where probands had psychoses, were ascertained from the Maudsley Twin Register in London (1948-1993). Lifetime history of DSM-III-R psychotic disorder and psychotic symptom dimensions was assessed from clinical records and research interviews and rated using the Operational Criteria Checklist. Estimates of heritability and environmental components of variance in liability were made with structural equation modeling using a causal-contingent common pathway model adapted for ascertainment from a clinical register. Significant heritability was found for DSM-III-R psychotic disorder (h² = 90%, 95%CI 68-94%) and the disorganized symptom dimension (h² = 84%, 95%CI 18-93%). The heritability for the disorganized dimension remained significant when influences acting through liability to psychosis were set to zero, suggesting that some influences on disorganization are modifying factors independent of psychosis liability. However, the relative extent of modifying factors versus influences acting through psychosis liability could not be clearly determined. To our knowledge, this study provides the first formal evidence of substantive heritability for the disorganized symptom dimension, and suggests that genetic loci influencing disorganization in individuals with psychoses are in some cases different from loci that influence risk of psychotic disorders themselves.