Multiple fregoli delusions after traumatic brain injury

Transforming Social Perspectives with Cognitive Maps

Growing evidence suggests that cognitive maps represent relations between social knowledge similar to how spatial locations are represented in an environment. Notably, the extant human medial temporal lobe literature assumes associations between social stimuli follow a linear associative mapping from an egocentric viewpoint to a cognitive map. Yet, this form of associative social memory doesn't account for a core phenomenon of social interactions in which social knowledge learned via comparisons to the self, other individuals, or social networks are assimilated within a single frame of reference. We argue that hippocampal-entorhinal coordinate transformations, known to integrate egocentric and allocentric spatial cues, inform social perspective switching between the self and others. We present evidence that the hippocampal formation helps inform social interactions by relating self versus other social attribute comparisons to society in general, which can afford rapid and flexible assimilation of knowledge about the relationship between the self and social networks of varying proximities. We conclude by discussing the ramifications of cognitive maps in aiding this social perspective transformation process in states of health and disease.

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.

Using hypnosis to model Fregoli delusion and the impact of challenges on belief revision

Fregoli delusion involves the belief that strangers are known people in disguise. We aimed to model aspects of this delusion for the first time using hypnosis. We informed hypnotised subjects that someone would enter the room (a confederate) and they would believe this person was someone they knew in disguise. After testing their reaction to the confederate, we challenged their delusion by directly contradicting their belief and then asking them to focus on the confederate's voice and gait. Finally, we indexed whether they could identify photographs of the confederate. We found that just over half of our high hypnotisable subjects identified the confederate as someone they knew in disguise. Although many highs abandoned their belief in response to challenges, some maintained strong, unwavering conviction that the confederate was a known person. We discuss these findings in terms of how evidence might be evaluated during both hypnotic and clinical delusions.

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.

Delusional misidentification syndromes and dementia: a border zone between neurology and psychiatry

The delusional misidentification syndromes (DMSs) are psychopathologic phenomena in which a patient consistently misidentifies persons, places, objects, or events. Although often described in relation to psychotic states including schzofrenia, it is, nevertheless, widely considered that these syndromes have an anatomical basis because of their frequent association with organic brain disease; studies have pointed to the presence of identifiable lesions, especially in the right frontal lobe and adjacent regions, in a considerable proportion of patients. The purpose of this article is to examine the phenomenon in people with dementia. We searched the electronic databases for original research and review articles on DMS in patients with dementia using the search terms "Delusional Misidentification Syndrome, Capgras syndrome, Fregoli syndrome, reduplicative paramnesia, and dementia." The DMSs are a frequent problem in dementia. The violence and dangerousness in patients with dementia having these syndromes are well documented, and forensic aspects are highlighted. Pathogenetic viewpoint and management are considered.

Psychosis Following Traumatic Brain Injury

Psychosis following traumatic brain injury (PFTBI) has received modest empirical investigation, and is subsequently poorly understood, identified and treated. The current article reports on consistencies in PFTBI phenomenology according to the existing peer-reviewed literature. The potential for psychotic symptoms post TBI, aetiological propositions, prevalence, significance of onset latency and injury severity, clinical and cognitive neuropsychological presentation and injury localisation/neuroimaging data are reviewed. Substantial methodological limitations associated with the majority of publications informing this work are also discussed. Despite controversies in the literature, psychosis following TBI appears to be three times more prevalent than psychotic disorders in the general population, and comparable in presentation to other idiopathic psychotic spectrum disorders, including schizophrenia.

Relationship between cognition and awareness of deficit in mild cognitive impairment

OBJECTIVE

Although anosognosia is common in Alzheimer's disease (AD), limited research has investigated awareness among patients with mild cognitive impairment (MCI). The current study examined cognitive performance differences between MCI patients who were aware or unaware of their deficits.

METHODS

Participants were 65 patients who underwent a comprehensive neuropsychological evaluation and diagnosed with MCI according to Petersen's criteria. Participants were divided into groups based on clinician rating of awareness (aware n=30 or unaware n=35), which was determined following interview with the patient and family member. Neuropsychological measures were converted into z-scores based on sample mean and standard deviation and averaged across cognitive domains. Frontal behavioral ratings were also collected.

RESULTS

No significant differences were found between awareness groups for age, education, gender, or MMSE score. Individuals rated as unaware performed significantly worse in the learning domain and a trend for worse performance on the Dementia Rating Scale-II total score than those rated as aware. None of the other cognitive or behavioral domains differed between the groups. Clinician and informant ratings of anosognosia were only modestly correlated, and we found an unexpected pattern of relationships between informant ratings and cognitive performance.

CONCLUSIONS

Awareness deficits are common in MCI patients. Our results argue against the most common etiologic hypotheses in AD (i.e., executive and right hemisphere) and suggest that severity of encoding deficits underlie anosognosia in MCI.

Impaired semantic memory in the formation and maintenance of delusions post-traumatic brain injury: a new cognitive model of delusions

This paper proposes a new cognitive model to explain the aetiology of delusions irrespective of diagnosis and/or phenomenology. The model hypothesises the influence of two processes in the formation and maintenance of delusions; (i) impaired perceptual abilities, particularly affect perception, which fosters the encoding of (ii) idiosyncratic semantic memories, especially those with an affective/self-referential valence. Previous research has established that schizophrenia patients with delusions have impaired semantic memory function. In the current paper we sought to provide evidence for (ii) abnormal semantic processing in persons with delusions with an alternative aetiology. Performance of four cases with a significant delusion post a traumatic brain injury was examined on a broad range of semantic memory tests. Overall semantic processing was impaired in the four cases relative to a normative healthy control sample. Cases performed better on tasks which required categorical identification, relative to the novel production of semantic information, which was poor in all four of the cases. These data offer preliminary evidence for our hypothesis of impaired semantic processing in persons with delusions. Findings will need to be empirically verified in larger sample groups and in those with alternative aetiologies.

The misidentification syndromes as mindreading disorders

The patient with Capgras' syndrome claims that people very familiar to him have been replaced by impostors. I argue that this disorder is due to the destruction of a representation that the patient has of the mind of the familiar person. This creates the appearance of a familiar body and face, but without the familiar personality, beliefs, and thoughts. The posterior site of damage in Capgras' is often reported to be the temporoparietal junction, an area that has a role in the mindreading system, a connected system of cortical areas that allow us to attribute mental states to others. Just as the Capgras' patient claims that that man is not his father, the patient with asomatognosia claims that his arm is not really his. A similar account applies here, in that a nearby brain area, the supramarginal gyrus, is damaged. This area works in concert with the temporoparietal junction and other areas to produce a large representation of a mind inside a body situated in an environment. Damage to the mind-representing part of this system (coupled with damage to executive processes in the prefrontal lobes) causes Capgras' syndrome, whereas damage to the body-representing part of this system (also coupled with executive damage) causes asomatognosia.

Prominent and persistent loss of past awareness in amnesia: delusion, impaired consciousness or coping strategy?

Profound loss of awareness for the past in amnesia has implications for our understanding of memory and belief systems, and how they may become disrupted in neurological conditions. We report the case of CW, a professional musician who became severely amnesic in 1985 following herpes simplex viral encephalitis (HSVE) at the age of 46 years. For many years CW stated several times a day that he had just woken up. He frequently wrote this in his diary too. When shown examples of his diary entries or videos of himself playing or conducting music, he recognised both his handwriting and himself on the video screen but stated vehemently that he "was not conscious then". In a previous paper (Wilson, Baddeley, & Kapur 1995), it was suggested that this lack of awareness for the past was a delusion, defined as a strongly held belief in the face of contradictory evidence (rather than implying any kind of psychiatric disorder per se). As a contribution to the academic debate regarding theories of "self", in the present paper we will review this explanation of CW's state as it had been in those early years, and we will also consider two other possibilities - namely, that CW had suffered from a loss of "autobiographical self" or "extended consciousness" (see Damasio, 2000, pp. 198-199), and that his verbal reports simply reflected a form of coping strategy to help him deal with the limited evidence he had available in "declarative" memory.

Frégoli syndrome accompanied with prosopagnosia in a woman with a 40-year history of schizophrenia

A 68-year-old woman with schizophrenia after a cerebrovascular accident resulting in right medial temporal and occipital damage developed Frégoli syndrome. Neuropsychological testing revealed that she had impairment in facial recognition compatible with prosopagnosia. The Frégoli syndrome disappeared in three month when, remarkably, her prosopagnosia also disappeared. Our findings are consistent with the hypothesis that combination of hyperactivations of temporo-limbic connection and frontal dysfunction may account for the development of Frégoli syndrome.

Neuroanatomical correlates of neuropsychiatric symptoms in Alzheimer's disease

Alzheimer's disease research has largely concentrated on the study of cognitive decline, but the associated behavioural and neuropsychiatric symptoms are of equal importance in the clinical profile of the disease. There is emerging evidence that regional differences in brain atrophy may align with variant disease presentations. The objective of this study was to identify the regions of decreased grey matter (GM) volume which were associated with specific neuropsychiatric behaviours in patients with mild Alzheimer's disease. Voxel-based morphometry was used to correlate GM derived from T(1)-weighted MRI images of 31 patients with mild Alzheimer's disease and specific neuropsychiatric symptoms and behaviours measured by the Neuropsychiatric Inventory. Delusions were associated with decreased GM density in the left frontal lobe, in the right frontoparietal cortex and in the left claustrum. Apathy was associated with GM density loss in the anterior cingulate and frontal cortex bilaterally, the head of the left caudate nucleus and in bilateral putamen. Agitation was associated with decreased GM values in the left insula, and in anterior cingulate cortex bilaterally. Neuropsychiatric symptoms of Alzheimer's disease seem to associate with neurodegeneration of specific neural networks supporting personal memory, reality monitoring, processing of reward, interoceptive sensations and subjective emotional experience. The study of neurodegenerative disorders such as Alzheimer's disease using voxel-based morphometry and other imaging modalities may further the understanding of the neural structures that mediate the genesis of abnormal behaviours.

An odd manifestation of the Capgras syndrome: loss of familiarity even with the sexual partner

We report the case of a patient who presented visual hallucinations and identification disorders associated with a Capgras syndrome. During the Capgras periods, there was not only a misidentification of his wife's face, but also a more global perceptive and emotional sexual identification disorder. Thus, he had sexual intercourse with his wife's "double" without having the slightest recollection feeling of familiarity towards his "wife" and even changed his sexual habits. To the best of our knowledge, he is the only neurological patient who made his wife a mistress. Starting from this global familiarity loss, we discuss the mechanism of Capgras delusion with reference to the role of the implicit system of face recognition. Such behavior of familiarity loss not only with face but also with all intimacy aspects argues for a specific disconnection between the ventral visual pathway of face identification and the limbic system involved in emotional and episodic memory contents.

Objective metamemory testing captures awareness of deficit in Alzheimer's disease

For reasons that remain unknown, there is marked inter-person variability in awareness of episodic memory loss in patients with Alzheimer's disease (AD). Existing research designs, primarily subjective in nature, have been at a relative disadvantage for evaluating disordered metamemory and its relation to the clinical and neuropathological heterogeneity of AD, as well as its prognosis for various disease outcomes. The current study sought to establish an objective means of evaluating metamemory in AD by modifying traditional metacognitive paradigms in which participants are asked to make predictions regarding their own memory performance. Variables derived from this measure were analyzed in relation to clinically rated awareness for memory loss. As predicted, a range of awareness levels existed across patients with mild to moderate AD (n=24) and clinical ratings of awareness (CRA) were significantly associated with verbal episodic memory monitoring (r = .46, p = .03). Further, patients who were rated as aware of their memory loss remained well calibrated over the course of the task whereas those rated as relatively unaware grew over-confident in their predictions [F (1, 33) = 4.19, p = .02]. Findings suggest that over-confidence may be related to impaired online error recognition and compromised use of metamemory strategies such as the Memory for Past Test (MPT) heuristic. Importantly, clinically rated awareness did not vary as a function of demographic variables, global cognition, or verbal memory. However, participants characterized as relatively unaware were impaired on a nonverbal memory task as compared to aware participants [F (1, 20) = 6.98, p = .02]. The current study provides preliminary support for the use of a recognition-based verbal episodic memory monitoring task as a quantitative measure of awareness for memory loss in AD, and offers insight into the manner in which metamemory breaks down. Discrepancies in nonverbal memory across the two awareness groups provide preliminary support for the idea that metamemory variability in AD may be related to the neuroanatomic presentation of the disease, with disordered awareness potentially reflective of a critical level of right hemisphere involvement.

Different SPECT findings before and after Capgras' syndrome in interictal psychosis

We herein report a case of Capgras' syndrome observed in interictal psychosis in which the single-photon emission computed tomography (SPECT) findings before and after the appearance of the psychotic symptoms differed. SPECT with 99mTc-hexamethyl propyleneamine oxine (HMPAO) revealed worsening of hypoperfusion in the entire right hemisphere after onset of the psychotic symptoms. The enhanced hypoperfusion demonstrated by SPECT in the present case seems to indicate a right interhemispheric disconnection resulting in the occurrence of Capgras' syndrome.

Where in the brain is the self?

Localizing the self in the brain has been the goal of consciousness research for centuries. Recently, there has been an increase in attention to the localization of the self. Here we present data from patients suffering from a loss of self in an attempt to understand the neural correlates of consciousness. Focusing on delusional misidentification syndrome (DMS), we find that frontal regions, as well as the right hemisphere appear to play a significant role in DMS and DMS related disorders. These data are placed in the context of neuroimaging findings.

Metacognitive theory and assessment in dementia: do we recognize our areas of weakness?

Anosognosia, disordered awareness of cognitive and behavioral deficits, is a striking and common symptom of Alzheimer's disease (AD), yet its etiology, clinical correlates, and prognostic value are unclear. Historically, disordered awareness has been a conceptually challenging phenomenon, evidenced by the numerous and diverse theories that aim to explain the manner in which this syndrome arises. We review many of these theories, focusing on the neuroanatomic substrates of awareness, and highlighting the potential roles of critical regions such as the right prefrontal and parietal cortices in enabling self-awareness. We then address methodological limitations such as use of subjective measurement tools that likely contribute to the conceptual ambiguity surrounding anosognosia. We argue that metacognitive techniques used in healthy adults, such as the Feeling of Knowing task, offer models for dissecting awareness into clear and identifiable cognitive components in patients with AD. We critique several studies that have pioneered such tasks in AD, and offer guidelines for future implementation of such methods. A final goal of this review is to advocate for a multidimensional approach to studying metacognitive skills that will facilitate the objective investigation of deficit awareness as it relates to a variety of disease variables such as prognosis, neuropsychological profile, neuropathological distribution, psychiatric symptoms, and clinical course.

Delusional misidentification

The Capgras syndrome and other forms of delusional misidentification may be encountered frequently in neuropsychiatric settings. DMS can occur in the presence of idiopathic psychiatric illness, in diffuse brain illness such as dementia, and in focal neurologic disease. In patients who have focal lesions, there is evidence that right hemisphere damage is necessary for the production of DMS. Although DMS is associated with a pattern of neuropsychologic impairments in the domains of memory, perception, and executive function, these impairments alone do not account for the selectivity and delusional nature of DMS. Therefore, other factors such as premorbid psychopathology, motivation, and loss of ego functions may be important in determining which vulnerable patients develop DMS and which do not.

Psychophysiological differences in schizophrenics with and without delusional misidentification syndromes: a P300 study

There is a debate on whether delusional misidentification syndromes (DMSs) and schizophrenia are distinct disorders. Information-processing deficits have been found in both. Since the P300 component of event-related potentials (ERPs) reflects attention and working memory (WM) mechanisms, the P300 elicited during a WM test was studied in schizophrenic patients with DMS in comparison to schizophrenic patients without DMS and controls. Nine schizophrenic patients with DMS, 11 without DMS and 11 healthy controls were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. P300 amplitude in prefrontal areas was found to be significantly reduced in schizophrenics without DMS and markedly less in DMS patients compared to controls. P300 latency in the central midline brain region was significantly prolonged in DMS patients compared to the other groups. Memory performance was significantly reduced in both patient groups as compared to healthy controls. The results may indicate abnormalities in both allocation of attentional resources and automatic orienting in schizophrenic patients with DSM. In contrast, even though schizophrenic patients without DMS exhibit partial similarities with patients suffering from DMS, they show excessive reduction of P300 amplitude located at the left frontal area. Future studies might clarify these issues.

Psychophysiological evidence for altered information processing in delusional misidentification syndromes

Recent research provides evidence that delusional misidentification syndromes (DMS) are associated with cognitive deficits. However, the underlying mechanisms of these deficits are not known. Since the P300 component of event-related potentials (ERPs) is related to fundamental aspects of working memory (WM), the present study is focused on P300 elicited during a WM test in DMS patients, as compared to those of healthy controls. Nine patients with DMS and 11 healthy controls, matched for age, sex and educational level were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. DMS patients showed significant reductions in P300 amplitude at the right frontal region compared to healthy controls. P300 latency in the central midline brain region was significantly prolonged in the DMS group. Each of these measures classified correctly 90% of the two groups. Moreover, the memory performance of the patient group was significantly lower, relatively to healthy controls. These findings provide evidence supporting the suggestion that DMS is associated with psychophysiological alterations occurring at the right frontal region, which mediates automatic processes, as well as with an irregular allocation of attentional resources, involving the interhemispheric circuitry, possibly due to gray matter degeneration. Finally, present work points to a need for further research investigating the characteristics, causes, course and treatment of severe cognitive deficits associated with DMS.

Abnormal P300 in a case of delusional misidentification with coinciding Capgras and Frégoli symptoms

The Delusional Misidentification Syndrome (DMS) is thought to be related to dissociation between recognition and identification processes. Working memory (WM) is considered responsible for the integration and online manipulation of information, so that it is available for further processing. Since the P300 component of event-related potentials (ERPs) is considered as an index of the on-line updating of WM, the present study is focused on auditory P300 elicited during a WM test in DMS, compared with that in healthy controls. ERPs, elicited during a WM test, in a case suffering from coinciding Capgras and Frégoli symptoms, were recorded. Peak amplitude and latency of the averaged P300 waveforms, as well as memory performance of this case, were compared to the patterns obtained from healthy controls. In relation to normal controls, the patient exhibited significantly attenuated amplitude of P300 at the F4, P3 and Pz abductions. The patient also showed significantly prolonged latencies of P300 at all abductions used. These findings suggest that DMS may be accompanied by WM dysfunction affecting brain regions outside the prefrontal cortex, as well as within, and by diffuse failure to allocate attention resources to a stimulus, as they are reflected by P300 amplitudes and latencies respectively. Additionally, it may be suggested that techniques designed to explore cognitive operations, such as recording of ERPs, and more specifically P300, during WM tasks, could provide further insights into the relationship between neural functioning and the cognitive deficits in DMS.