Delusions

A large and growing body of research in computational psychiatry draws on Bayesian modelling to illuminate the dysfunctions and aberrations that underlie psychiatric disorders. After identifying the chief attractions of this research programme, we argue that its typical focus on abstract, domain-general inferential processes is likely to obscure many of the distinctive ways in which the human mind can break down and malfunction. We illustrate this by appeal to psychosis and the social phenomenology of delusions.

Introduction: Cotard delusion—the delusional belief “I am dead”—is named after the French psychiatrist who first described it: Jules Cotard (1880, 1882). Ramachandran and Blakeslee (1998) proposed that the idea “I am dead” comes to mind when a neuropathological condition has resulted in complete abolition of emotional responsivity to the world. The idea would arise as a putative explanation: if “I am dead” were true, there would be no emotional responsivity to the world. Methods: We scrutinised the literature on people who (...) expressed the delusional belief “I am dead”, looking for data on whether such patients are reported as entirely lacking in emotional responsivity. Results: In numerous cases, patients with Cotard delusion are described as experiencing emotions including anxiety, fear, guilt, distress, euphoria and worry. Conclusions: We conclude that complete absence of emotional responsivity cannot be what prompts the delusional idea that one is dead. We propose that, in at least some cases, the idea “I am dead” comes to mind in response to symptoms of depersonalisation or derealisation, often present in cases of Cotard delusion, and give examples of Cotard patients with abnormalities in various neural areas that could be responsible for the presence of such symptoms. (shrink)

Current frameworks propose that delusions result from aberrant belief updating due to altered prediction error (PE) signaling and misestimation of environmental volatility. We aimed to investigate whether behavioral and neural signatures of belief updating are specifically related to the presence of delusions or generally associated with manifest schizophrenia.Our cross-sectional design includes human participants (nfemale/male=6625/41), stratified into four groups: healthy participants with minimal (n=22) or strong delusional-like ideation (n=18), and participants with diagnosed schizophrenia with minimal (n=13) or strong delusions (n=13), resulting (...) in a 2x2 design, which allows to test for the effects of delusion and diagnosis. Participants performed a reversal learning task with stable and volatile task contingencies during fMRI scanning. We formalized learning with a hierarchical Gaussian filter model and conducted model-based fMRI analysis regarding beliefs of outcome uncertainty and volatility, precision-weighted PEs of the outcome- and the volatility-belief.Patients with schizophrenia as compared to healthy controls showed lower accuracy and heightened choice switching, while delusional ideation did not affect these measures. Participants with delusions showed increased precision-weighted PE-related neural activation in fronto-striatal regions. People with diagnosed schizophrenia overestimated environmental volatility and showed an attenuated neural representation of volatility in the anterior insula, medial frontal and angular gyrus.Delusional beliefs are associated with altered striatal PE-signals. Juxtaposing, the potentially unsettling belief that the environment is constantly changing and weaker neural encoding of this subjective volatility seems to be associated with manifest schizophrenia, but not with the presence of delusional ideation. (shrink)

How shall we distinguish religious delusion from sane religious belief? Making this determination is not usually found to be difficult in clinical practice – but what shall be our theoretical rationale? Attempts to answer this question often try to provide differentiating principles by which the religious “sheep” may be separated from the delusional “goats.” As we shall see, none of these attempts work. We may, however, ask whether the assumption underlying the search for a differentiating principle – that religious beliefs (...) and religious delusions can usefully be considered species of a common genus – is a good one. In this paper, we outline an alternative, “disjunctive,” understanding of religious belief and religious delusion. By reminding ourselves both of what is central to any delusion and of what distinguishes bona fide religious claims from their pretenders, we show how to resolve our reflective puzzlement about religious delusion without recourse to differentiating principles. (shrink)

In this paper, I argue (1) that the contents of some delusions are believed with sufficient confidence; (2) that a delusional subject could have a conscious belief in the content of his delusion (p), and concurrently judge a contradictory content (not-p) – his delusion could be transparent (Krstić 2020), and (3) that the existence of even one such case reveals a problem with pretty much all existing accounts of lying, since it suggests that one can lie by asserting what one (...) consciously and confidently believes is true, and (4) sincerity, since it suggests that asserting a proposition you believe is true is neither sufficient nor necessary for sincerity. If I am right about (1) and (2), then (3) and (4) follow easily. Therefore, the paper is mainly devoted to an analysis of transparent delusion and defending (1) and (2). (shrink)

Delusions are usually depicted in one of two contrasting ways. They are either characterized as harmful and dysfunctional beliefs or as fostering engagement with the environment and sometimes even psychological wellbeing in the face of psychological or biological difficulties – something which, according to some accounts, would make them biologically adaptive. It is this “adaptive hypothesis” that I focus on in this paper, by empirically investigating the adaptiveness of delusions in a sample of people suffering from OCD. The paper shows (...) that delusions in OCD entertain complex and heterogeneous relationships with psychological wellbeing and engagement with the environment, highlighting some future directions that clinical and philosophical research on the topic should take. (shrink)

ABSTRACT 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. (shrink)

We all have experiences in which it “seems clear” to us that something is true. This kind of clear experience can play significant roles in determining whether we believe something to be true. But what are the significant roles? So far, the literature has focused on optimal cases where a person's clear experience might provide prima facie justification for their belief. This article will develop the hypothesis that, in less optimal cases, these clear experiences can be epistemically damaging. Specifically, it (...) will argue that, in certain cases, such experiences may causally compel belief even in the face of counterevidence. (shrink)

How does it come about that a person akratically believes that P, while at the same time believing that the available evidence speaks against that P? Among the current accounts, Scanlon offers an intuitive suggestion that one’s seeming experience that P may play an important role in the aetiology of their akratic belief that P. However, it turns out to be quite challenging to articulate what the role of seeming experience is. This paper will offer a novel development of Scanlon’s (...) intuitive suggestion, with a focus on clear-eyed epistemic akrasia. I will argue that the primary role of seeming experience is unlikely to act as the subject’s reason or to provide the subject with prima facie justification; instead, based on the recent work in dogmatism and Cartesian clarity, I will propose a causal account, according to which, when it seems clear to the subject that P, the seeming experience may exert a brute causal force to persistently compel the subject to believe that P. This causal account also has the advantage of helping some existing accounts to explain clear-eyed epistemic akrasia. (shrink)

Delusional perception designates a sudden, idiosyncratic, and often self-referential delusion triggered by a neutral perceptual content. In classical psychopathology, delusional perception was considered almost pathognomonic for schizophrenia. Since delusional perception has been erased from ICD-11 and always been absent in DSM, it risks slipping out of clinical awareness. In this article, we explore the clinical roots of delusional perception, elucidate the psychopathological phenomenon, and discuss its two predominant conceptualizations, i.e., Schneider’s well-known two-link model and Matussek’s lesser known one-link model. The (...) two-link model posits that delusional perception amounts to an abnormal interpretation of an intact perception, whereas the one-link model posits that the delusional meaning is contained within a changed perception. Despite their differences, both models stress that delusional perception is a primary delusion that takes place within an altered experiential framework that is characteristic of the psychopathological Gestalt of schizophrenia. We discuss the role of delusional perception in future psychopathological and diagnostic assessment and argue that such assessments must be conducted in comprehensive manner, eliciting the psychopathological context within which symptoms and signs are embedded. Finally, we discuss the compatibility of the two models of delusional perception with contemporary cognitive models on delusion and cognitive psychotherapeutic approaches. (shrink)

Philosophy is witnessing an “Agential Turn,” characterised by the thought that explaining certain distinctive features of human mentality requires conceiving of many mental phenomena as acts, and of subjects as their agents. We raise a challenge for three central explanatory appeals to mental agency––agentialism about doxastic responsibility, agentialism about doxastic self‐knowledge, and an agentialist explanation of the delusion of thought insertion: agentialists either commit themselves to implausibly strong claims about the kind of agency involved in the relevant phenomena, or make (...) appeals to agency which seem explanatorily redundant. The agentialist literature does not contain a clear answer to this Agentialist Dilemma, and we put it forward here as a core challenge for the Agential Turn. But we also accept the fundamental motivation behind the Agential Turn, its critique and rejection of a purely passivist and spectatorial conception of the human mind. We close by urging the recognition of a broader category of rational subjectivity, a category which includes states which are neither active nor passive, but nevertheless form part of a subject's rational point of view on the world. (shrink)

This commentary on Adam Pautz's excellent book, Perception, explores the consequences of “spatial illusionism,” the view that the spatial properties presented in experience aren't instantiated in the extra-mental world. First, I consider whether spatial illusionism entails that our ordinary beliefs about the physical world are mostly false. I then argue that spatial illusionism threatens to undermine two arguments Pautz's defends in Perception: his argument that sense data theory is incompatible with physicalism, and his central argument against the internal physical state (...) view of perception. (shrink)

A growing number of studies in both the scientific and the philosophical literature have drawn on a Bayesian predictive processing framework to account for the formation of delusions. The key here is that delusions form because of disrupted prediction error signalling. Parrott’s recent critique argues that the framework is incomplete in two respects: it leaves unclear why delusional hypotheses are selected over none at all or over more plausible alternatives; it leaves unclear how exactly it is that delusional hypotheses are (...) generated in the first place. In this paper, we defend the framework’s explanatory power by way of showing how it can go a long way in helping disentangle these concerns. We take up each of them in turn. As for the first, our argument turns on two claims: a) believing nothing, although possible in principle, may not be a viable procedure in the circumstances; b) alternative hypotheses may be rendered unavailable for selection, due to aberrant prediction errors. As for the second concern, we distinguish three ways in which delusional hypotheses may be initially acquired, all of which are based on experience broadly construed. (shrink)

Delusions are standardly defined as attitudes that are not amenable to change in light of conflicting evidence. But what evidence do people with delusion have for and against it? Do delusions really go against their total evidence? How are the answers affected by different conceptions of evidence? -/- This chapter focuses on how delusions relate to evidence. I consider what delusions-relevant evidence people with delusions have. I give some reasons to think that people typically have evidence for their delusions, and (...) that the evidence they have against them is often overstated. I draw on this discussion to consider whether delusions are evidentially supported and epistemically rational. Finally, I discuss implications for the nature of delusion, responsibility, and treatment and suggest directions for future research. Throughout, the discussion is sensitive to different conceptions of evidence and rationality in epistemology. -/- A central upshot is that what we should say about the epistemic standing of delusions depends substantively on our positions in epistemology, in particular, on the debate between internalists and externalists about evidence. If we want clarity on the epistemic standing of delusions, we need to incorporate more sophisticated tools from epistemology. (shrink)

Anorexia nervosa involves seemingly irrational beliefs about body size and the value of thinness. Historically, researchers and clinicians have avoided referring to such beliefs as delusions, instead opting for the label ‘overvalued ideas’. I discuss the relationship between the beliefs associated with anorexia nervosa and the distinction between delusions and overvalued ideas, as it is conceived in both European and American psychiatric traditions. In doing so, I question the benefit of applying the concepts of delusion and overvalued idea to anorexia (...) nervosa and raise some issues with contemporary use of the Brown Assessment of Beliefs scale for assessing the level of delusionality associated with the disorder. (shrink)

I would like to thank Sullivan-Bissett and Noordhof for their stimulating comments on my 2023 paper in Neuroethics. In this reply, I will (1) articulate some deeper disagreements that may underpin our disagreement on the nature of delusion, (2) clarify their misrepresentation of my previous arguments as a defence of the two-factor theory in particular, and (3) finally conduct a comparison between the Maherian one-factor theory and the two-factor theory, showing that the two-factor theory is better supported by evidence.

This chapter introduces the rationalist model of delusions. It begins by presenting John Campbell’s seminal proposal that delusions are caused top-down by pathological Wittgensteinian framework or hinge beliefs. After presenting Campbell’s rationalist account of delusions, the chapter raises and examines prominent objections by Tim Bayne & Elisabeth Pacherie as well as by Tim Thornton. The former make an important distinction between the aetiological top-down cognitive part and the epistemological rationalist framework part of Campbell’s account. The thesis that delusions are caused (...) top-down by pathological beliefs is not equivalent to the thesis that delusions are Wittgensteinian framework certainties. This chapter endorses this distinction. While the arguments against the top-down aspect are found to be more convincing – which motivates popular two-factor theories – the rationalist framework model of delusions is defended as an epistemologically promising account of delusion. Finally, this chapter examines a range of developments that have been made taking Campbell’s rationalism as a starting point. Most prominently the section examines Eilan’s early development of rationalism and Rhodes and Gipps’ proposal that delusions are not framework propositions but a product of their absence. (shrink)

This chapter connects the phenomenon of double bookkeeping to two critical debates in the philosophy of delusion: one from the analytic tradition and one from the phenomenological tradition. First, I will show how the failure of action guidance on the part of some delusions suggests an argument to the standard view that delusions are beliefs (doxasticism about delusion) and how its proponents have countered it by ascribing behavioral inertia to avolition, emotional disturbances, or a failure of the surrounding environment in (...) supporting the agent’s motivation to act. Second, I will show how the mismatch between the experience of double bookkeeping and that of having the usual propositional attitudes of folk psychology suggests another, more recalcitrant argument not only against doxasticism but against the very attempt to fit delusion into folk psychology. Third, I will show how phenomenologically inspired theories of delusion, such as the multiple realities hypothesis, bypass the debates above and focus on describing and understanding the disturbances in the structure of experience undergone by patients. I conclude that the philosophical discussions ensuing from an appreciation of double bookkeeping show some of the limitations of the analytic philosophical approach to delusion. (shrink)

It is argued that in order to properly engage with the debate regarding the ethics of belief one first needs to determine the nature of the propositional attitude in question. This point is illustrated by discussing a related topic from social philosophy, broadly conceived, concerning the nature of, and inter-relationship between, delusions and the Wittgensteinian notion of a hinge commitment. Are we to understand either or both of these notions as beliefs? Are delusions a kind of hinge commitment? In answering (...) these questions we will appeal to a distinction between folk belief and knowledge-apt belief. It is argued that while both delusions and hinge commitments count as beliefs in the former sense, neither is a belief in the latter sense. Moreover, once we understand what is involved in the notion of a hinge commitment, it will also become clear why delusions are not hinge commitments. It is claimed that by gaining an understanding of delusions and hinge commitments, and thereby of two fundamental ways of thinking about belief, we will be in a better position to determine what is at issue in the ethics of belief debate. (shrink)

Monothematic delusions are bizarre beliefs which are often accompanied by highly anomalous experiences. For philosophers and psychologists attracted to the exploration of mental phenomena in an evolutionary framework, these beliefs represent—notwithstanding their rarity—a puzzle. A natural idea concerning the biology of belief is that our beliefs, in concert with relevant desires, help us to navigate our environments, and so, in broad terms, an evolutionary story of human belief formation will likely insist on a function of truth (true beliefs tend to (...) lead to successful action). Monothematic delusions are systematically false and often harmful to the proper functioning of the agent and the navigation of their environment. So what are we to say? A compelling thought is that delusions are _malfunctioning_ beliefs. Compelling though it may be, I argue against this view on the grounds that it does not pay due attention to the circumstances in which monothematic delusions are formed, and fails to establish _doxastic_ malfunction. I argue instead that monothematic delusions are _misfunctioning_ beliefs, that is, the result of mechanisms of belief formation operating in historically abnormal conditions. Monothematic delusions may take their place alongside a host of other strange beliefs formed in difficult epistemic conditions, but for which no underlying doxastic malfunction is in play. (shrink)

Chenwei Nie ([22]) argues against a Maherian one-factor approach to explaining delusion. We argue that his objections fail. They are largely based on a mistaken understanding of the approach (as committed to the claim that anomalous experience is sufficient for delusion). Where they are not so based, they instead rest on misinterpretation of recent defences of the position, and an underestimation of the resources available to the one-factor theory.

In this paper I argue that in her new book, Why Delusions Matter, Lisa Bortolotti offers us a new way to dispel a major objection to psychedelic assisted psychoterapy, the Comforting Delusions Objection.

INTRODUCTION: A number of prescribed medicines have been reported in cases of drug-induced delusion, such as dopaminergic agents or psychostimulants. But to this day, most studies are based on a limited number of cases and focus on a few drug classes, so a clear overview of this topic remains difficult. To address this issue, we provide in this article a comprehensive analysis of drug-induced delusion, based on the World Health Organization (WHO) pharmacovigilance database. METHODS: We performed a disproportionality analysis of (...) this database using the information component (IC). The IC compares observed and expected values to find associations between drugs and delusion, using disproportionate Bayesian reporting. An IC0.25 (lower end of the IC 95 credibility interval) \textgreater 0 is considered statistically significant. RESULTS: Here we present an analysis of 4559 suspected drug-induced delusion reports in the WHO pharmacovigilance database. These results identified 66 molecules statistically associated with delusion and an extensive analysis of confounding factors and coprescriptions was performed, using full database as background with an IC0.25 \textgreater 0. The main drug classes involved were antidepressants, antiepileptics, dopaminergic agents, opioids, antiinfective agents, benzodiazepines, anti-dementia drugs and psychostimulants. CONCLUSION: These results will help clinicians identify potential suspected drugs associated with delusion and decide which drug to discontinue and eventually lead to a re-evaluation of drug labels for some molecules. (shrink)

The aim of this paper is twofold. First, I want to re-examine the epistemic status of elaborated delusions. Bortolotti (2016, 2020) claims that they can be epistemically innocent. However, I will show that this type of delusions is more unique than suggested by the existing analyses of their epistemic status. They typically cause more profound harms than other kinds of delusions, and in most cases, it would be counterproductive to classify them as epistemically beneficial or innocent. I will employ predictive (...) and phenomenological models of delusions and the enactivist notion of sensus communis to explain the harms and possible benefits of elaborated delusions and why I think the existing definition does not fully grasp them. Based on this analysis, I will propose changes to the conditions for epistemic innocence. (shrink)

When we talk about delusions we may refer to symptoms of mental health problems, such as clinical delusions in schizophrenia, or simply the beliefs that people cling to which are implausible and resistant to counterevidence; these can include anything from beliefs about the benefits of homeopathy to concerns about the threat of alien abduction. Why do people adopt delusional beliefs and why are they so reluctant to part with them? In Why Delusions Matter, Lisa Bortolotti explains what delusions really are (...) and argues that, despite their negative reputation, they can also play a positive role in people's lives, imposing some meaning on adverse experiences and strengthening personal or social identities. In a clear and accessible style, Bortolotti contributes to the growing research on the philosophy of the cognitive sciences, offering a novel and nuanced view of delusions. (shrink)

Monothematic delusions are delusions whose contents pertain to a single subject matter. Examples include Capgras delusion, the delusion that a loved one has been replaced by an impostor, and Cotard delusion, the delusion that one is dead or does not exist. Two-factor accounts of such delusions hold that they are the result of both an experiential deficit, for instance flattened affect, coupled with an aberrant cognitive response to that deficit. In this paper we develop a new expressivist two-factor account of (...) delusion. In contrast to existing endorsement and explanationist accounts, which treat delusions as either explanations or endorsements of the contents of these disordered experiences, we hold that delusional beliefs have an expressive function: they characterize, in impressionistic terms, what the subject’s experience is like for them. We show how our account improves upon existing two-factor views in explaining the central features of monothematic delusions, in particular the way in which delusional subjects fall short of the ideal of rationality. (shrink)

This book presents new philosophical work on delusions and their impact on everyday human behavior. It explores a cluster of related topics at the intersection of philosophy of mind and psychiatry, while also charting the historical development of work on delusions. Within psychiatry, there are several disputes about the nature and origin of delusions. Whereas some authors see only an abnormal phenomenon that needs to be treated by psychological or pharmacological means, others hold that delusions can be psychologically adaptive and (...) even have epistemic benefits. This book brings together an interdisciplinary group of contributors to build consensus around what delusions are and how they impact the human mind. Part 1 provides readers with an informed historical discussion of delusions and carefully examines the contemporary impact of these historical perspectives. Part 2 analyzes the impact of contemporary views of delusions on the mental and emotional life of human agents. Finally, Part 3 explores the normative frameworks of delusions and analyzes the impact of some of their behavioral consequences on the daily life of subjects and their caregivers. The Philosophy and Psychology of Delusions is essential reading for researchers and graduate students working at the intersection of philosophy, psychiatry, and psychology. (shrink)

Delusions have traditionally been considered the hallmark of mental illness, and their conception, diagnosis and treatment raise many of the fundamental conceptual and practical questions of psychopathology. One of these fundamental questions is whether delusions are understandable. In this paper, we propose to consider the question of understandability of delusions from a philosophy of language perspective. For this purpose, we frame the question of how delusions can be understood as a question about the meaning of delusional utterances. Accordingly, we ask: (...) “what meaning(s) can delusional utterances possibly have?”. We argue that in the current literature, there is a standard approach to the meaning of delusional utterances, namely the descriptive account which assumes that a delusional utterance “p” means that p is the case. Drawing on Speech Act Theory, we argue that solely relying on the descriptive account disregards essential ways of how linguistic meaning is constituted. Further, we show that Speech Act Theory can prove a helpful addition to the theoretical and clinical “toolbox” used for attempting to understand delusional utterances. This, we believe, may address some of the theoretical and clinical shortcomings of using only the currently predominant descriptive account. (shrink)

BACKGROUND: Reasoning biases have been suggested as risk factors for delusional ideation in both patients and non-clinical individuals. Still, it is unclear how these biases are longitudinally related to delusions in the general population. We hence aimed to investigate longitudinal associations between reasoning biases and delusional ideation in the general population. METHODS: We conducted an online cohort study with 1184 adults from the German and Swiss general population. Participants completed measures on reasoning biases (jumping-to-conclusion bias JTC, liberal acceptance bias LA, (...) bias against disconfirmatory evidence BADE, possibility of being mistaken PM) and delusional ideation at baseline, and delusional ideation 7 to 8 months later. RESULTS: A greater JTC bias was associated with a greater increase in delusional ideation over the following months. This association was better described by a positive quadratic relationship. Neither BADE, LA nor PM were associated with subsequent changes in delusional ideation. CONCLUSIONS: This study suggests that jumping-to-conclusions predicts delusional ideation in the general population but that this association may follow a quadratic trajectory. While no other associations turned significant, future studies with shorter temporal distances may shed further light on the role of reasoning biases as risk factors for delusional ideation in non-clinical samples. (shrink)

This work sets out to present how the notion of delusion may be understood (and extended) within the semantic framework of Robert Brandom's inferentialism. The mechanisms of reliability and community‐oriented proprieties, among others, provide inferentialists with effective tools for understanding commitments (and so beliefs) in communities. These tools may be used to describe and assess both commitments that we might consider sound and commitments that we might consider delusional, both in terms of how they arise and in terms of how (...) they may be reinforced. Delusions are accordingly rendered in perspectival and normative terms, which is elaborated through a number of examples. The picture of how a delusional commitment may be understood, how it may be reinforced, and its character as community internal or external provide some interesting perspectives on delusions in shared social contexts, as well as how they may originate intractable conflicts and disconnects between sub‐groups within a broader linguistic community. (shrink)

INTRODUCTION: Delusional misidentification syndromes (DMS) are a group of psychopathological experiences occurring in psychosis, involving the misidentification of a person or place. DMS are often accompanied by hostility towards the object of delusional misidentification. This is of a particular concern in perinatal mental illness due to the potential disruption of the mother-infant bond, and risk of neglect, violence, or infanticide towards a misidentified child. This review aimed to collate all published cases of DMS in postpartum psychosis to further understand how (...) these syndromes present in perinatal mental illness. METHODS: In August 2021, an online database search was conducted using PubMed, MEDLINE, PsycINFO, CINAHL, and Embase to identify all publications reporting DMS in the perinatal period. RESULTS: Nine papers were included in the review involving 8 case reports of Capgras syndrome and one case series involving 4 cases of Fregoli syndrome. Three cases identified organic pathology, which may have contributed to the presentation. The most common subject of misidentification was the patient’s husband (n = 7), followed by their baby (n = 6), hospital staff (n = 4), other family members (n = 3), and self (n = 1). Five cases remark on the impact of perinatal illness on the maternal-infant bond, of which four result in the mother being unwilling to care for the infant as the result of their delusional beliefs. CONCLUSION: This is the first systematic review of the literature in this field. Although small in number, these cases reveal several important learning points including that DMS can occur with or without underlying organic disease. Active exploration of the nature of delusions in postpartum psychosis is required to mitigate the risk of harm to the infant and mother-infant bond. It may also uncover that these syndromes are more common in postpartum psychosis than previously realized. (shrink)

Delusions can be many things. They can be symptoms of mental health problems, such as schizophrenia, clinical delusions, or simply the beliefs that people cling to which are unsupported by evidence. We call the latter everyday delusions and they can include anything from the benefits of homeopathy to the dangers of alien abduction. Yet, why do people adopt delusional beliefs and why can they be so reluctant to part with them? In Why Delusions Matter, Lisa Bortolotti explains what delusions really (...) are and that despite their negative reputation, that they can also play a positive role in someone's life, such as providing meaning to people’s experiences and strengthening their identities. In a clear and accessible style, she contributes to the growing study of philosophy and the cognitive sciences, providing an intelligent and nuanced view of delusions. (shrink)

The cognitive science of belief is a burgeoning field, with insights ranging from detailing the fundamental structure of the mind, to explaining the spread of fake news. Here we highlight how new insights into belief acquisition, storage, and change can transform our understanding of psychiatric disorders. Although we focus on monothematic delusions, the conclusions apply more broadly. -/- .