The misidentification syndromes as mindreading disorders

Incidence and lesions causative of delusional misidentification syndrome after stroke

OBJECTIVE

To better elucidate the symptomatology and pathophysiological mechanisms underlying delusional misidentification syndrome (DMS), we investigated the incidence rate and symptomatic features of DMS following stroke and relationships among DMS, other neuropsychological symptoms, and lesion locations.

METHODS

The present study included 874 consecutive patients (371 women; mean age ± standard deviation = 72.2 ± 11.7 years) who were admitted to the rehabilitation wards at two hospitals within 2 months of their first stroke. We examined the clinical features and lesion sites of patients with DMS and compared them with those of a control group of patients with hemi-spatial neglect without DMS using voxel-based lesion-symptom mapping (VLSM).

RESULTS

Among the 874 patients who experienced a stroke, we observed 10 cases of Fregoli syndrome. No other DMS subtypes were observed; however, eight patients exhibited somatoparaphrenia (five of them also had Fregoli syndrome) and one also exhibited reduplicative paramnesia. Right hemispheric lesions were found in all 10 cases. VLSM revealed statistically significant overlapping lesion sites specifically related to Fregoli syndrome when compared with the control group. The sites included the insula, inferior frontal lobe, anterior temporal lobe, and subcortical limbic system in the right hemisphere (i.e., areas connected by the uncinate fasciculus).

CONCLUSION

The DMS incidence was 1.1% among patients after stroke. All patients had Fregoli syndrome and half had somatoparaphrenia, suggesting that the two syndromes share an underlying pathology. Lesions found with Fregoli syndrome were concentrated around the right uncinate fasciculus; this has not been reported in previous research.

Looking into a Deluded Brain through a Neuroimaging Lens

Delusions are irrational, tenacious, and incorrigible false beliefs that are the most common symptom of a range of brain disorders including schizophrenia, Alzheimer's, and Parkinson's disease. In the case of schizophrenia and other primary delusional disorders, their appearance is often how the disorder is first detected and can be sufficient for diagnosis. At this time, not much is known about the brain dysfunctions leading to delusions, and hindering our understanding is that the complexity of the nature of delusions, and their very unique relevance to the human experience has hampered elucidation of their underlying neurobiology using either patients or animal models. Advances in neuroimaging along with improved psychiatric and cognitive modeling offers us a new opportunity to look with more investigative power into the deluded brain. In this article, based on data obtained from neuroimaging studies, we have attempted to draw a picture of the neural networks involved when delusion is present and evaluate whether different manifestations of delusions engage different regions of the brain.

The role of the IPL in person identification

We investigate the brain activations when identifying a newly encountered individual as being the same as a person previously perceived, a fundamental but seldom acknowledged process. In an identity condition, two faces had to be identified as the same person in contrast to a control condition, in which two faces had to be recognised as belonging to similar looking twins. Our results demonstrate an increase of neural activation in frontal as well as in parietal areas including the left inferior parietal lobe and the precuneus during identification. We introduce mental files theory to model this process as a linking of co-referential files and identify important connections to other domains in neurological and cognitive science (e.g., delusional misidentification syndromes, theory of mind).

Windows into the Visual Brain: New Discoveries about the Visual System, Its Functions, and Implications for Practitioners

Introduction

In recent years, major progress has been made in understanding the human visual system because of new investigative techniques. These developments often contradict older concepts about visual function.

Methods

A detailed literature search and interprofessional discussions.

Results

Recent innovative neurological tests are described that are able to show much more accurately the visual pathways, the process of vision, and the close relationships among sensory modalities. These tests also reveal the remarkable neuroplasticity of the human brain and disorders of connectivity that frequently involve visual function.

Discussion

How these recent neurological advances may benefit service providers is discussed.

Implications for practitioners

It is important that from time to time new neurological and ophthalmic developments are summarized for professionals who are involved in the clinical management of individuals with visual disorders and how the newly acquired knowledge affects the diagnosis and intervention strategies. Visual rehabilitation must be based on up-to-date science, which continually changes and grows with research.

Finding the imposter: brain connectivity of lesions causing delusional misidentifications

SEE MCKAY AND FURL DOI101093/AWW323 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Focal brain injury can sometimes lead to bizarre symptoms, such as the delusion that a family member has been replaced by an imposter (Capgras syndrome). How a single brain lesion could cause such a complex disorder is unclear, leading many to speculate that concurrent delirium, psychiatric disease, dementia, or a second lesion is required. Here we instead propose that Capgras and other delusional misidentification syndromes arise from single lesions at unique locations within the human brain connectome. This hypothesis is motivated by evidence that symptoms emerge from sites functionally connected to a lesion location, not just the lesion location itself. First, 17 cases of lesion-induced delusional misidentifications were identified and lesion locations were mapped to a common brain atlas. Second, lesion network mapping was used to identify brain regions functionally connected to the lesion locations. Third, regions involved in familiarity perception and belief evaluation, two processes thought to be abnormal in delusional misidentifications, were identified using meta-analyses of previous functional magnetic resonance imaging studies. We found that all 17 lesion locations were functionally connected to the left retrosplenial cortex, the region most activated in functional magnetic resonance imaging studies of familiarity. Similarly, 16 of 17 lesion locations were functionally connected to the right frontal cortex, the region most activated in functional magnetic resonance imaging studies of expectation violation, a component of belief evaluation. This connectivity pattern was highly specific for delusional misidentifications compared to four other lesion-induced neurological syndromes (P < 0.0001). Finally, 15 lesions causing other types of delusions were connected to expectation violation (P < 0.0001) but not familiarity regions, demonstrating specificity for delusion content. Our results provide potential neuroanatomical correlates for impaired familiarity perception and belief evaluation in patients with delusional misidentifications. More generally, we demonstrate a mechanism by which a single lesion can cause a complex neuropsychiatric syndrome based on that lesion's unique pattern of functional connectivity, without the need for pre-existing or hidden pathology.

Implicit Recognition of Familiar and Unfamiliar Faces in Schizophrenia: A Study of the Skin Conductance Response in Familiarity Disorders

OBJECTIVE

Familiarity is a subjective sensation that contributes to person recognition. This process is described as an emotion-based memory-trace of previous meetings and could be disrupted in schizophrenia. Consequently, familiarity disorders could be involved in the impaired social interactions observed in patients with schizophrenia. Previous studies have primarily focused on famous people recognition. Our aim was to identify underlying features, such as emotional disturbances, that may contribute to familiarity disorders in schizophrenia. We hypothesize that patients with familiarity disorders will exhibit a lack of familiarity that could be detected by a flattened skin conductance response (SCR).

METHOD

The SCR was recorded to test the hypothesis that emotional reactivity disturbances occur in patients with schizophrenia during the categorization of specific familiar, famous and unknown faces as male or female. Forty-eight subjects were divided into the following 3 matched groups with 16 subjects per group: control subjects, schizophrenic people with familiarity disorder, and schizophrenic people without familiarity disorders.

RESULTS

Emotional arousal is reflected by the skin conductance measures. The control subjects and the patients without familiarity disorders experienced a differential emotional response to the specific familiar faces compared with that to the unknown faces. Nevertheless, overall, the schizophrenic patients without familiarity disorders showed a weaker response across conditions compared with the control subjects. In contrast, the patients with familiarity disorders did not show any significant differences in their emotional response to the faces, regardless of the condition.

CONCLUSION

Only patients with familiarity disorders fail to exhibit a difference in emotional response between familiar and non-familiar faces. These patients likely emotionally process familiar faces similarly to unknown faces. Hence, the lower feelings of familiarity in schizophrenia may be a premise enabling the emergence of familiarity disorders.

A Mental Files Approach to Delusional Misidentification

I suggest that we can think of delusional misidentification in terms of systematic errors in the management of mental files. I begin by sketching the orthodox “bottom-up” aetiology of delusional misidentification. I suggest that the orthodox aetiology can be given a descriptivist or a singularist interpretation. I present three cases that a descriptivist interpretation needs to account for. I then introduce a singularist approach, one that is based on mental files, and show how it opens the way for different and potentially more plausible accounts of these three cases. I reflect on how this mental files approach can be viewed either as a supplement to the orthodox aetiology, or as suggesting an altogether different aetiology. I end by addressing a concern surrounding the explanatory power of mental files.

"Cat-gras" delusion: a unique misidentification syndrome and a novel explanation

ABSRACT Capgras syndrome is a distressing delusion found in a variety of neurological and psychiatric diseases where a patient believes that a family member, friend, or loved one has been replaced by an imposter. Patients recognize the physical resemblance of a familiar acquaintance but feel that the identity of that person is no longer the same. Here we describe a 73-year-old male with right posterior frontal and bilateral anterior-medial frontal damage from prior brain trauma with a similar delusion of an imposter replacing his pet cat. Misidentification syndromes for animals, as opposed to humans, have been rarely reported. Neuropsychological testing showed deficits in executive processing and memory retrieval with prominent intrusions and false positive responses. The delusional belief content in Capgras syndrome has been hypothesized to result from loss of an emotional or autonomic response to familiar stimuli, from theory of mind deficits, or from loss of self-environment distinctions. We instead propose that Capgras delusions result from a dysfunction in linking external stimuli with retrieved internal autobiographical memories pertaining to that object. This leads to an erroneously learned identity that persists as a specific delusional belief.

Puzzling Confabulations – An Overview of Classifications and Theories

Abstract. Confabulations comprise a puzzling collection of false statements, produced without conscious intent to deceive. They have been classified according to the mode of elicitation (spontaneous vs. provoked), the content (fantastic vs. plausible), the memory domain in which they become manifest (episodic vs. semantic), their stability (stable vs. ephemeral), or their selectivity (monothematic vs. multithematic). All classifications appear to be problematic, because there are no clear-cut dichotomies, and confabulations often seem to fall into overlapping categories. There are, in fact, many theories, presumably explaining different kinds of confabulations; the best bet is to regard them as complementary rather than competing.

Cotard Syndrome without Depressive Symptoms in a Schizophrenic Patient

Introduction. Cotard syndrome is a rare condition characterized by nihilistic delusions concerning body or life that can be found in several neuropsychiatry conditions. It is typically associated with depressive symptoms. Method. We present a case of Cotard syndrome without depressive symptoms in the context of known paranoid schizophrenia. A literature review of Cotard syndrome in schizophrenia was performed. Results. Although there are few descriptions of this syndrome in schizophrenia, patients usually present depressive mood and psychomotor retardation, features not seen in our patient. Loss of the sense of the inner self, present in schizophrenia, could explain patient's symptomatology but neurobiological bases of this syndrome remain unclear. Conclusion. Despite not being considered in actual classifications, Cotard syndrome is still relevant and psychiatric evaluation is critical to diagnosing and treating this condition in psychiatric patients.

Delusional misidentification syndromes in obsessive-compulsive disorder

Delusional misidentification syndromes (DMS) have been rarely reported in patients with conditions other than schizophrenia-related disorders, diffuse brain disease (dementia) and focal neurological illness. In this report, we describe DMS (i.e. Capgras and Fregoli syndromes) in two patients with severe and treatment resistant obsessive-compulsive disorder (OCD), one with paranoid personality disorder (PPD) and the other with a pervasive developmental disorder (PDD) not otherwise specified. While our findings highlight an interesting phenomenon (the occurrence of DMS in OCD), it is presently unclear whether this association is rare or underreported. Misidentification syndromes might be the ultimate result of a combination of obsessive fears and preexisting cognitive bias/deficits, such as mistrustfulness (in PPD) or poor theory of mind (in PDD).

Memories of Art

Although the art-historical context of a work of art is important to our appreciation of it, it is our knowledge of that history that plays causal roles in producing the experience itself. This knowledge is in the form of memories, both semantic memories about the historical circumstances, but also episodic memories concerning our personal connections with an artwork. We also create representations of minds in order to understand the emotions that artworks express.

Confabulation, delusion, and anosognosia: motivational factors and false claims

False claims are a key feature of confabulation, delusion, and anosognosia. In this paper we consider the role of motivational factors in such claims. We review motivational accounts of each symptom and consider the evidence adduced in support of these accounts. In our view the evidence is strongly suggestive of a role for motivational factors in each domain. Before concluding, we widen the focus by outlining a tentative general taxonomy of false claims, including false claims that occur in clinical settings as well as more garden-variety false claims, and incorporating both motivational and nonmotivational approaches to explaining such claims.