Delusion formation and insight in the context of affective disturbance

Aberrant modulation of brain activation by emotional valence during self-referential processing among patients with delusions of reference

BACKGROUND AND OBJECTIVES

Delusions of reference are thought to reflect abnormally heightened attributions of salience to mundane events or stimuli that lead to convictions that they are personally significant or directed at the observer. Recent findings highlight abnormal recruitment of brain regions associated with self-referential processes among patients with referential delusions. Given the inherent overlap of emotion, incentive salience, and self-relevance, as well as with aberrant thought processes in psychosis, this study investigated the implicit relations between participants' perception of the emotional valence of stimuli on neural correlates of self-referent judgments among schizophrenia-spectrum patients with referential delusions.

METHODS

During fMRI scanning, participants indicated whether sentences describing personal characteristics seemed to refer specifically to them. Subsequently, participants rated their perceived emotional valence of each statement.

RESULTS

Regression analyses revealed differential relations between groups across regions associated with self-referential processing, including prefrontal regions, anterior cingulate, insula, precuneus, and dorsal striatum. Within these regions, greater activation related to sentences rated as more positive among healthy comparison participants and more negative among patients.

LIMITATIONS

The current results warrant replication and extension with larger and longitudinal samples to assess potential moderating relations of clinical and demographic individual differences.

CONCLUSIONS

These findings support aberrant brain activation associated with emotional and salience brain networks in schizophrenia and highlight the importance of considering specific emotional attributes (valence) in discrete domains of delusional thought (self-referential communication).

Explaining Delusions: Reducing Uncertainty Through Basic and Computational Neuroscience

Delusions, the fixed false beliefs characteristic of psychotic illness, have long defied understanding despite their response to pharmacological treatments (e.g., D2 receptor antagonists). However, it can be challenging to discern what makes beliefs delusional compared with other unusual or erroneous beliefs. We suggest mapping the putative biology to clinical phenomenology with a cognitive psychology of belief, culminating in a teleological approach to beliefs and brain function supported by animal and computational models. We argue that organisms strive to minimize uncertainty about their future states by forming and maintaining a set of beliefs (about the organism and the world) that are robust, but flexible. If uncertainty is generated endogenously, beliefs begin to depart from consensual reality and can manifest into delusions. Central to this scheme is the notion that formal associative learning theory can provide an explanation for the development and persistence of delusions. Beliefs, in animals and humans, may be associations between representations (e.g., of cause and effect) that are formed by minimizing uncertainty via new learning and attentional allocation. Animal research has equipped us with a deep mechanistic basis of these processes, which is now being applied to delusions. This work offers the exciting possibility of completing revolutions of translation, from the bedside to the bench and back again. The more we learn about animal beliefs, the more we may be able to apply to human beliefs and their aberrations, enabling a deeper mechanistic understanding.

Memories reactivated under ketamine are subsequently stronger: A potential pre-clinical behavioral model of psychosis

BACKGROUND

Sub-anesthetic doses of the NMDA antagonist ketamine have been shown to model the formation and stability of delusion in human subjects. The latter has been predicted to be due to aberrant prediction error resulting in enhanced destabilization of beliefs. To extend the scope of this model, we investigated the effect of administration of low dose systemic ketamine on memory in a rodent model of memory reconsolidation.

METHODS

Systemic ketamine was administered either prior to or immediately following auditory fear memory reactivation in rats. Memory strength was assessed by measuring freezing behavior 24h later. Follow up experiments were designed to investigate an effect of pre-reactivation ketamine on short-term memory (STM), closely related memories, and basolateral amygdala (BLA) specific destabilization mechanisms.

RESULTS

Rats given pre-reactivation, but not post-reactivation, ketamine showed larger freezing responses 24h later compared to vehicle. This enhancement was not observed 3h after the memory reactivation, nor was it seen in a closely related contextual memory. Prior inhibition of a known destabilization mechanism in the BLA blocked the effect of pre-reactivation ketamine.

CONCLUSIONS

Pre- but not post-reactivation ketamine enhances fear memory. These data together with recent data in human subjects supports a model of delusion fixity that proposes that aberrant prediction errors result in enhanced destabilization and strengthening of delusional belief.

An investigation of a novel transdiagnostic model of delusions in a group with positive schizotypal symptoms

INTRODUCTION

Although several theories of delusions have been put forward, most do not offer a comprehensive diagnosis-independent explanation of delusion aetiology. This study used a non-clinical sample to provide empirical support for a novel transdiagnostic model of delusions that implicates aberrant semantic memory and emotion perception processes as key factors in delusion formation and maintenance. It was hypothesised that among a non-clinical sample, people high in schizotypy would demonstrate differences in semantic memory and emotion perception, relative to people low in schizotypy.

METHODS

Using the Cognitive Disorganisation subscale of the Oxford-Liverpool Inventory of Feelings and Experiences, 41 healthy participants were separated into high and low schizotypy groups and completed facial emotion perception and semantic priming tasks.

RESULTS

As expected, participants in the high schizotypy group demonstrated different performance on the semantic priming task and reduced facial affect accuracy for the emotion anger, and reaction time differences to fearful faces.

CONCLUSION

These findings suggest that such processes may be involved in the development of the sorts of unusual beliefs which underlie delusions. Investigation of how emotion perception and semantic memory may interrelate in the aetiology of delusions would be of value in furthering our understanding of their role in delusion formation.

Influence of COMT val158met and ADRA2B deletion polymorphisms on recollection and familiarity components of human emotional memory

Emotional enhancement of memory is a widely accepted phenomenon that, in addition to its adaptive role, may play a role in the evolution of psychiatric disorders. Hence a comprehensive understanding of its neurobiological basis is imperative. Whilst the pharmacological and neural mechanisms are well known, the contribution of genetic variation is not. Research suggests that two qualitatively different processes (recollection and familiarity) contribute to recognition memory. In this study, we examined the relative contribution of two common genetic polymorphisms, the deletion variant of the ADRA2B gene that codes the α2b adrenergic receptor and the val158met polymorphism of the COMT gene that codes the catechol-O-methyltransferase enzyme, to emotional enhancement of these two memory processes in 97 healthy male volunteers. There was a significant interaction between COMT genotype and emotional arousal in relation to recollection, but not familiarity, with the former being significantly elevated for emotionally arousing versus neutral pictures in carriers of the val158 allele compared with met158 carriers. There were no main effects or interactions in relation to ADRA2B genotype.

Toward a model of cognitive insight in first-episode psychosis: verbal memory and hippocampal structure

Our previous work has linked verbal learning and memory with cognitive insight, but not clinical insight, in individuals with a first-episode psychosis (FEP). The current study reassessed the neurocognitive basis of cognitive and clinical insight and explored their neural basis in 61 FEP patients. Cognitive insight was measured with the Beck Cognitive Insight Scale (BCIS) and clinical insight with the Scale to assess Unawareness of Mental Disorder (SUMD). Global measures for 7 domains of cognition were examined. Hippocampi were manually segmented in to 3 parts: the body, head, and tail. Verbal learning and memory significantly correlated with the BCIS composite index. Composite index scores were significantly associated with total left hippocampal (HC) volume; partial correlations, however, revealed that this relationship was attributable largely to verbal memory performance. The BCIS self-certainty subscale significantly and inversely correlated with bilateral HC volumes, and these associations were independent of verbal learning and memory performance. The BCIS self-reflectiveness subscale significantly correlated with verbal learning and memory but not with HC volume. No significant correlations emerged between the SUMD and verbal memory or HC volume. These results strengthen our previous assertion that in individuals with an FEP cognitive insight may rely on memory whereby current experiences are appraised based on previous ones. The HC may be a viable location among others for the brain system that underlies aspects of cognitive insight in individuals with an FEP.

The affective neuropsychology of confabulation and delusion

The paper reviews the history of the scientific understanding of the role of emotion in confabulation and delusion. I argue that the significance of emotion in the pathogenesis of these symptoms was obscured by academic polarisation between psychodynamic and neurocognitive traditions and was also often obfuscated by rigid distinctions between psychogenic and neurogenic explanations. This tradition of epistemic dualism was implicitly maintained in the fields of cognitive neuropsychology and cognitive neuropsychiatry. This paper focuses on memory-related confabulation following ventromedial frontal lobe lesions, awareness-related confabulation following right perisylvian lesions, and delusions of various aetiologies. Ambiguity regarding the definition and taxonomy of symptoms renders direct comparison difficult, but certain overriding principles are becoming discernible. Recent findings suggest that emotion and motivation influence both confabulation and delusion. These influences may be instigated directly by neural dysfunction or indirectly by life changes and altered social circumstances, or by a combination of these. Importantly, the rejection of epistemic dualism in the conceptualisation of both symptoms can allow us to study them in parallel and draw conclusions about the relation between cognition and emotion. Specifically, confabulation and delusion can be described as faulty attempts to balance the conflicting demands of accurate and self-serving reality representation.

Hippocampal abnormalities and memory deficits: new evidence of a strong pathophysiological link in schizophrenia

The central goals of this manuscript are (1) to better characterize what appears to be the most parsimonious account of schizophrenic long-term memory impairment in the neuropsychological literature: a contextual binding deficit rooted in the medial temporal lobes; (2) to link this deficit to concrete abnormalities at the level of the hippocampus; and (3) to suggest that this deficit could lead to the functional impairment experienced by schizophrenia patients in their daily lives. As far as long-term memory is concerned in schizophrenia, there seems to be a general agreement to conclude that explicit mechanisms are disturbed compared to relatively spared implicit mechanisms. More precisely, both subsystems of explicit memory (i.e., episodic and semantic) appear to be dysfunctional in this patient population. Errors during the encoding processes could be responsible for this dysfunction even if retrieval per se is not totally spared. Recently, a number of studies have suggested that impairments in conscious recollection and contextual binding are closely linked to episodic memory deficit. Since the hippocampal formation is considered to be the central element in the neural support for contextual binding and episodic memory, we have conducted an extensive review of the literature concerning the hippocampal formation in schizophrenia. Emerging evidence from varying disciplines confirm the coherence of the different anomalies reported concurrently at the neuroanatomical, neurodevelopmental, biochemical, and genetic levels. It seems highly probable that the synaptic disorganization in the hippocampus concerns the regions crucial for encoding and contextual binding memory processes. The consequences of these deficits could result in schizophrenia patients experiencing major difficulties when facing usual events which have not been encoded with their proper context.

Theories of delusional disorders. An update and review

Delusional syndromes can occur in a number of psychiatric, neurological or other disorders. They can also be caused by neurotoxic agents (e.g., heavy metals) as well as substance addiction. There are several hypotheses on the underlying cognitive or emotional processes associated with organic factors of delusional disorders, depending on the patient groups examined and the methods used. The aim of this paper is to provide a comprehensive review and critical assessment of the various, rather heterogeneous theories in this field.

Metacognitive control over false memories: a key determinant of delusional thinking

This article reviews the current literature on false memories in schizophrenia. Increasing evidence suggests that neither memory impairment in general nor false memories in particular can reliably differentiate patients with schizophrenia or delusions from psychiatric controls. In contrast, it is proposed that a reduced metacognitive awareness of one's own fallibility, and overconfidence in errors, may predispose a person to fixed, false beliefs (ie, delusions). Congruent with this position, a number of recent investigations suggest that the memory of patients with schizophrenia, as well as healthy subjects scoring high on delusional ideation, is corrupted by an increased number of incorrect memories held with high confidence, possibly relating to a jumping-to-conclusions or liberal acceptance bias in schizophrenia spectrum disorders. A new training approach is described that is intended to sharpen patients' awareness of such errors and reduce confidence in fallible memories. Some empirical gaps and directions for further research are outlined.

The dynamics of insight in the prodrome of schizophrenia

INTRODUCTION

Schizophrenia is characterized by diminished insight, which fluctuates with disease progression. Insight deterioration in the prodrome of schizophrenia is poorly understood. Despite pharmacologic treatment, including early interventions, there is a high risk of relapse and need of acute care in schizophrenia patients.

OBJECTIVE

To study if insight deterioration occurs during the prodrome and if insight preservation early in the illness might predict a better prognosis.

METHODS

Data was collected retrospectively from the records of 24 patients initially diagnosed with schizophrenia during a 2-year period. Patients' progress was then tracked over a 3-year period. Insight was determined by a physician's subjective evaluation, patient interest and participation in treatment planning, and patient accuracy in reporting behaviors and symptoms when compared with reports from collaterals.

RESULTS

Ten patients were determined to have insight regarding the developing illness at different presentations at the hospital. Insight preservation correlated with less need for emergency visits and fewer hospitalization days (P<.005). It was also associated with more depressive and anxious mood (P<.000). Patients and family members described early, ego-dystonic perceptual disturbances followed by diminished insight. Awareness into the illness, symptoms, and attribution of symptoms to the illness fluctuated at different presentations in the insight group. In the other group, insight was nil at each presentation after the psychotic debut.

CONCLUSION

Most patients maintain insight during the perceptual disturbance phase. Insight diminishes as the early delusional phase sets in. Higher levels of preserved insight seem to correlate with less need for acute treatment. Further research in this area is warranted for determining if early insight oriented interventions in the prodromal phase can improve the prognosis of schizophrenia.