The Fregoli Delusion: A Disorder of Person Identification and Tracking

Delusions in postpartum Psychosis: Implications for cognitive theories

Postpartum psychosis is a rare but serious condition that can affect women after childbirth. We present a case study of an individual with no comorbidities or psychiatric history who developed postpartum psychosis characterised by prominent misidentification delusions whilst admitted to hospital. The woman recovered quickly with medication and showed no evidence of relapse over the following three years. Whilst still symptomatic and after recovery, the patient was able to provide a detailed description of her experiences. Contemporaneous interviews and observations during her hospital admission and a subsequent detailed retrospective account provide a unique, comprehensive window into her experience of these time-limited delusions. Her case reveals important insights including the triggers for her misidentification delusions, the role of social and contextual influences on delusional beliefs, and her recall of active involvement in evaluating and discarding delusional hypotheses. These insights highlight the complexity of delusional beliefs, challenge existing theories of delusions, and help inform broader theories of belief formation.

Anton, Balint, Charles Bonnet, and the Others: The ABC of Cerebral Visual Syndromes (A Historical Guide and an Update)

Cerebral visual impairments have been of great interest to neurologists, ophthalmologists, and neuroscientists. Complicated or partial varieties related to cortical blindness are discussed in this review. They are a fascinating alphabet of eponymic clinical syndromes, bordering neurology, ophthalmology, and even psychiatry. Recent functional imaging and experimental studies have contributed further knowledge of cognitive visual organization in addition to the classical lesion evidence.

Oh it's me again: Déjà vu, the brain, and self-awareness

Déjà vu and involuntary autobiographical memories (IAMs) are differentiated by a number of factors including metacognition. In contrast to IAMs, déjà vu activates regions associated with self-awareness including the right dorsolateral prefrontal cortex.

Neuropsychiatric Features of Fregoli Syndrome: An Individual Patient Meta-Analysis

OBJECTIVE

Fregoli syndrome is a rare delusion characterized by the belief that familiar people are presenting themselves disguised as others to the affected person. Theories of delusional misidentification have suggested secondary ("organic") underlying mechanisms; however, the pathoetiology of Fregoli syndrome has not been systematically evaluated. The investigators aimed to compare the neuropsychiatric features of Fregoli syndrome in primary and secondary psychoses.

METHODS

A systematic review and patient-level meta-analysis were conducted. Five databases were searched, ultimately yielding 83 studies that met selection criteria. Demographic characteristics, diagnosis, delusional content, neuropsychiatric features, investigations, and treatment information were extracted. Random-effects models were calculated, and odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.

RESULTS

A total of 119 patients with Fregoli syndrome were identified: 62 patients (52%) with primary psychosis, 50 (42%) with secondary psychosis, and seven (6%) with an unclear etiology. Patients with secondary psychosis were less likely than patients with primary psychosis to experience persecutory features (OR=0.26, 95% CI=0.10, 0.67; p=0.0057). Moreover, patients with secondary psychosis were more likely to experience Fregoli syndrome during a first episode of psychosis (OR=11.00, 95% CI=2.45, 49.39; p=0.0017). Right-sided brain lesions were more prominent than left-sided brain lesions in the total sample (χ²=5.0, df=1, p=0.025) and in the secondary psychosis subgroup (χ²=4.26, df=1, p=0.039).

CONCLUSIONS

This is the first meta-analysis to investigate Fregoli syndrome. An estimated 42% of the reported cases involved a secondary etiology. These findings provide clinicians with a better understanding of the symptomatology of Fregoli syndrome and have potential to be applied in future research and clinical practice.

Failure of hypothesis evaluation as a factor in delusional belief

INTRODUCTION

In accounts of the two-factor theory of delusional belief, the second factor in this theory has been referred to only in the most general terms, as a failure in the processes of hypothesis evaluation, with no attempt to characterise those processes in any detail. Coltheart and Davies ([2021]. How unexpected observations lead to new beliefs: A Peircean pathway. Consciousness and Cognition, 87, 103037. https://doi.org/10.1016/j.concog.2020.103037) attempted such a characterisation, proposing a detailed eight-step model of how unexpected observations lead to new beliefs based on the concept of abductive inference as introduced by Charles Sanders Peirce.

METHODS

In this paper, we apply that model to the explanation of various forms of delusional belief.

RESULTS

We provide evidence that in cases of delusion there is a specific failure of the seventh step in our model: the step at which predictions from (delusional) hypotheses are considered in the light of relevant evidence.

CONCLUSIONS

In the two-factor theory of delusional belief, the second factor consists of a failure to reject hypotheses in the face of disconfirmatory evidence.

Putting your money where your self is: Connecting dimensions of closeness and theories of personal identity

Studying personal identity, the continuity and sameness of persons across lifetimes, is notoriously difficult and competing conceptualizations exist within philosophy and psychology. Personal reidentification, linking persons between points in time is a fundamental step in allocating merit and blame and assigning rights and privileges. Based on Nozick's (1981) closest continuer theory we develop a theoretical framework that explicitly invites a meaningful empirical approach and offers a constructive, integrative solution to current disputes about appropriate experiments. Following Nozick, reidentification involves judging continuers on a metric of continuity and choosing the continuer with the highest acceptable value on this metric. We explore both the metric and its implications for personal identity. Since James (1890), academic theories have variously attributed personal identity to the continuity of memories, psychology, bodies, social networks, and possessions. In our experiments, we measure how participants (N = 1, 525) weighted the relative contributions of these five dimensions in hypothetical fission accidents, in which a person was split into two continuers. Participants allocated compensation money (Study 1) or adjudicated inheritance claims (Study 2) and reidentified the original person. Most decided based on the continuity of memory, personality, and psychology, with some consideration given to the body and social relations. Importantly, many participants identified the original with both continuers simultaneously, violating the transitivity of identity relations. We discuss the findings and their relevance for philosophy and psychology and place our approach within the current theoretical and empirical landscape.

Measles, magic and misidentifications: a defence of the two-factor theory of delusions

Corlett (Corlett, P. (this issue). Factor one, familiarity and frontal cortex: A challenge to the two-factor theory of delusions. Cognitive Neuropsychiatry) provides a robust critique of the two-factor theory of delusions. The heart of his critique is two challenges he derives from a paper by Tranel and Damasio (Tranel, D., & Damasio, H. (1994). Neuroanatomical correlates of electrodermal skin conductance responses. Psychophysiology, 31(5), 427-438), who illuminate the autonomic responses and brain damage of four patients often cited in support of the two-factor theory of Capgras delusion. I defend the two-factor theory against Corlett's two key challenges, arguing that his first challenge has been previously addressed, and that his second challenge is overstated. In my view, these challenges do not negate the two-factor account. Nevertheless, two-factor theorists - and computational psychiatrists - should continue to devise and test falsifiable predictions of their respective theories.

Understanding misidentification syndromes using the integrative memory model

Misidentification syndromes occur commonly in neuropsychiatric practice and can be explained through aberrant integration of recollection and familiarity, in keeping with a dysfunction at the level of the attributional system in the new integrative memory model. We examine neuroimaging findings associated with Fregoli and Capgras syndromes and compare these with the proposed neural substrate of the integrative memory model supporting the core and attribution functions.

Uncovering Capgras delusion using a large-scale medical records database

BACKGROUND

Capgras delusion is scientifically important but most commonly reported as single case studies. Studies analysing large clinical records databases focus on common disorders but none have investigated rare syndromes.

AIMS

Identify cases of Capgras delusion and associated psychopathology, demographics, cognitive function and neuropathology in light of existing models.

METHOD

Combined computational data extraction and qualitative classification using 250 000 case records from South London and Maudsley Clinical Record Interactive Search (CRIS) database.

RESULTS

We identified 84 individuals and extracted diagnosis-matched comparison groups. Capgras was not 'monothematic' in the majority of cases. Most cases involved misidentified family members or close partners but others were misidentified in 25% of cases, contrary to dual-route face recognition models. Neuroimaging provided no evidence for predominantly right hemisphere damage. Individuals were ethnically diverse with a range of psychosis spectrum diagnoses.

CONCLUSIONS

Capgras is more diverse than current models assume. Identification of rare syndromes complements existing 'big data' approaches in psychiatry.

DECLARATION OF INTERESTS

V.B. is supported by a Wellcome Trust Seed Award in Science (200589/Z/16/Z) and the UCLH NIHR Biomedical Research Centre. S.W. is supported by a Wellcome Trust Strategic Award (WT098455MA). Q.D. has received a grant from King's Health Partners.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

A Case of Reduplicative Paramnesia for Home

We present the case of a high-functioning 88-year-old woman who suddenly developed the persistent and disturbing belief that her home of 40 years was not genuine, but rather an accurate replica. Her episode was probably caused by a small stroke that left her with this single extremely specific deficit. We describe the patient in detail and link to a video interview of her 3 months after the onset of the delusion, eloquently describing her experience. We summarize some of the many reports and discussions of our patient's delusion, reduplicative paramnesia, as well as other delusional misidentification syndromes.

Psychotic symptoms in frontotemporal dementia

Although psychotic features have long been recognized in association with frontotemporal dementia (FTD), recent genetic discoveries enabling further subtyping of FTD have revealed that psychotic symptoms are frequent in some forms of FTD. Hallucinations and delusions can even precede onset of other cognitive or behavioural symptoms in patients with FTD. In this review, we explore the frequency and types of psychotic symptoms reported in patients with FTD, as well as in other neuropsychiatric disorders, to aid practitioners' consideration of these features in the diagnosis of FTD and related disorders.

Explaining person identification: an inquiry into the tracking of human agents

To introduce the issue of the tracking and identification of human agents, I examine the ability of an agent ("a tracker") to track a human person ("a target") and distinguish this target from other individuals: The ability to perform person identification. First, I discuss influential mechanistic models of the perceptual recognition of human faces and people (the face-recognition program). Such models propose detailed hypotheses about the parts and activities of the mental mechanisms that control the perceptual recognition of persons. However, models based on perceptual recognition are incomplete theories of person identification because they do not explain several identification behaviors that are fundamental to human social interactions (e.g., identifying unobservable persons and imposters). Furthermore, recognition-based models tend to appeal to the controversial concept of the "identity" of a person without explaining what determines personal identity and persistence. To overcome these limitations, I propose to integrate the face-recognition program into a broader causal-historical theory of identification. The causal-historical theory of identification complements models focused on perceptual recognition because it can account for the types of non-perceptual identification overlooked by the face-recognition program. Moreover, it can decompose the identification behaviors into tracking processes that succeed or fail to be sensitive to causal characteristics of a target. I illustrate these advantages with a discussion of the difference between the tracking of a person understood as either a causally continuous biological organism (organism-based tracking) or a psychologically continuous mind (psychological tracking). Finally, I argue that the causal-historical theory provides a theoretical framework for investigating the tracking of relations between a target and its contextual and historical attributes, such as a target's possessions.