Persecutory delusions: a cybernetic model.

The authors propose a cybernetic model for the formation and maintenance of persecutory delusions. During the formation of persecutory ideation, the threat of loss of control over the self or others interacts with predictions of control from others. This interaction may result in feelings of alien control followed by persecutory explanations. Since the persecutory explanations provide the individual with a new goal of resisting others' influence in order to prevent being controlled, they reduce the threat of loss of self-control. This is how persecutory delusions are maintained.     

Persecutory delusions in dementia.

BACKGROUND: Persecutory delusions are common in dementia. This study was undertaken to investigate the prevalence, associated factors, and characteristics of persecutory delusions in demented patients. METHOD: The sample population included 167 demented patients (DSM-III-R criteria) admitted to a geropsychiatric ward. Patients were assessed for the occurrence of any persecutory delusions since the onset of dementia. The content of persecutory delusions, the patients' response to the delusions, and any concomitant psychiatric symptoms were also explored. RESULTS: Of the 167 demented patients, 45 (26.9%) showed symptoms of persecutory delusions. Patients with persecutory delusions had a higher prevalence of other delusions, hallucinations, and physically aggressive behaviors. The deluded patients often thought that their caregivers were their persecutors and had a wide range of responses to their delusions. After they were hospitalized, many of these patients attacked medical staff and were uncooperative with treatment. CONCLUSION: Persecutory delusions are common in dementia of various types. Deluded patients often have vigorous responses to their delusions including physically aggressive behaviors and suicide attempts. Careful evaluation is needed to assess the potential for violent and suicidal behaviors in these patients. Medical staff should be alert to clinical strategies for handling the treatment of such patients when they become violent or uncooperative.     

Persecutory delusions and psychological well-being

Social Psychiatry and Psychiatric Epidemiology - Persecutory delusions are one of the key problems seen in psychotic conditions. The aim of the study was to assess for the first time the levels of...     

Persecutory delusions and the self: An investigation of implicit and explicit self-esteem

Persecutory delusions are proposed to be a defence against low self-esteem reaching conscious awareness (Bentall, Corcoran, Howard, Blackwood, & Kinderman, 2001). Key predictions of this proposal are that individuals with persecutory delusions will have lower implicit self-esteem and equivalent levels of explicit self-esteem compared to healthy controls. This study aims to test the predictions regarding implicit and explicit self-esteem in people with persecutory delusions. Of 22 people screened for persecutory delusions, 16 were recruited to the study. 20 healthy control participants were recruited. The Implicit Association Test was used to measure implicit self-esteem and the Rosenberg self-esteem scale was used to assess explicit self-esteem. Positive and negative self and other schemas were also assessed using the Brief Core Schema Scales. People with persecutory delusions had positive implicit self-esteem, comparable to that of the control group. Explicit self-esteem was lower for the persecutory delusion group, but was associated with increased depression and anxiety. Negative self and other schemas were higher in the clinical group. The results do not support the contention that persecutory delusions defend against negative self-representations and low self-esteem reaching conscious awareness. Non-defensive cognitive models are discussed as an alternative way of understanding persecutory delusions.     

Selective temporal attention enhances the temporal resolution of visual perception: Evidence from a temporal order judgment task

We investigated whether attending to a particular point in time affects temporal resolution in a task in which participants judged which of two visual stimuli had been presented first. The results showed that temporal resolution can be improved by attending to the relevant moment as indicated by the temporal cue. This novel finding is discussed in terms of the differential effects of spatial and temporal attention on temporal resolution.     

Response bias and aging on a recognition memory task.

Response bias reflects the decision rule an individual uses when faced with uncertainty on recognition memory tasks. Recent studies indicate frontal regions may mediate response bias performance. One theory of aging also implicates frontal lobe contributions in age-related cognitive changes. This suggests that frontal lobe changes may mediate response bias in older adults. Consistent with this frontal aging hypothesis, we predicted that response bias would become more liberal with age. Methods: Participants were 181 younger (30-49) and 112 older normal adults (75+) that were part of the California Verbal Learning Test-second edition (CVLT-2) normative sample (total n = 1078). We used parametric measures of discriminability and response bias provided by the CVLT-2 scoring program. Groups were similar in IQ and education. Multi-level regression models were created to examine the effects of moderating variables. The interaction between age and age group significantly predicted response bias. Post hoc analysis indicated that increasing age was associated with more liberal bias in the older but not in the younger group. In the light of reported relationships between frontal regions and both aging and response bias, we hypothesize that frontal changes may be the underlying mechanism explaining the increase in liberal response bias with age.     

Attentional and memory bias in persecutory delusions and depression

BACKGROUND: Previous research has indicated that persecutory delusions and depression may share similar cognitive biases at implicit levels of processing, but differentiate at explicit levels, supporting the theory that paranoia may have a protective function against underlying negative schemata. The study aimed to investigate attentional bias and both implicit and explicit memory biases for personally salient and standardised emotional stimuli in persecutory delusions and depression. SAMPLING: 36 participants, with 12 in each group, were interviewed in order to generate personally salient stimuli to be employed within the cognitive tests. Standardised emotional stimuli were additionally employed as a control. Participants completed two probe detection tasks, one including personally salient stimuli and one including standard emotional stimuli. Memory for the stimuli presented in this task was assessed by a free recall task (explicit memory) followed by a word completion task (implicit memory). RESULTS: On an implicit memory task, both the deluded and depressed groups displayed comparable retrieval of positive and negative words. However, on the explicit memory task, the depressed group demonstrated a bias for negative stimuli, whereas the deluded group demonstrated a bias for positive stimuli. The groups did not demonstrate an attentional bias for personally salient information. However, an attentional bias for standardised emotional stimuli was found in the depressed group, although this was not specific to either negative or positive stimuli. CONCLUSION: The results indicate that depression and persecutory delusions may share similar patterns of processing at an implicit level but differentiate at the explicit level, which may be indicative of cognitive avoidance of threatening stimuli in psychosis. However, this does not seem to be a feature of automatic attentional processes in people with persecutory delusions. Implications for further research are discussed.     

Focal transcranial magnetic stimulation and response bias in a forced-choice task.

The effects of transcranial magnetic stimulation were studied on the performance of a warned, forced-choice response time task by normal adults. The task consisted of extension of the index finger in response to the click produced by the discharge of the magnetic coil (go-signal). The subjects were asked to choose the right or left finger only after the go-signal was delivered. Single magnetic stimuli were delivered to the prefrontal or motor area, and in the control situation, away from the head. Magnetic stimulation affected hand preference only when it was delivered to the motor area. With stimulation of this area, subjects more often chose the hand contralateral to the site stimulated with response times that were mainly less than 200 ms. With longer response times (between 200 and 1100 ms), magnetic stimulation had no effect on hand preference regardless of the site stimulated. Stimulation of prefrontal areas yielded results similar to the control situation. These results suggest that response bias in this paradigm is caused by an effect of magnetic stimulation on neural structures within, or closely related to, the motor areas of the brain. Although the response bias was clear and predictable, the subjects were unaware of its existence. It is possible to influence endogenous processes of movement preparation externally without disrupting the conscious perception of volition.     

Functional topography during a visuoverbal judgment task studied with event-related desynchronization mapping.

Event-related desynchronization (ERD) of alpha components was studied in 10 subjects in a visuoverbal judgment task. EEG was recorded from 29 electrodes; ERD, measured by percentage of alpha power decrease, was calculated in 125-ms intervals and displayed in a time course over 7-s intervals and in the form of topographical ERD maps. ERD, interpreted as a measure of activated cortical areas, was studied in the upper and lower alpha bands. It was found that upper alpha band ERD was short-lasting (less than 1 s), localized to the posterior region and not found before stimulation; in contrast to this, lower alpha band ERD was longer-lasting (greater than 1 s), more widespread, with a left hemisphere dominance, and was already present before stimulation. ANOVA revealed significant interactions among alpha frequency bands, scalp location, and pre-/poststimulus intervals. The self-organizing topological Kohonen network was used to analyze the stability of consecutive ERD maps. There is evidence that topographical ERD patterns can be stable for about 300-400 ms.     

The neural basis of perceptual bias and response bias in the Landmark task

Spatial neglect as a multifaceted syndrome may consist of perceptual/attentional as well as motor/intentional components. The present study investigated the lesion anatomy underlying perceptual and response bias using a manual response Landmark task (Bisiach, Ricci, Lualdi, & Colombo, 1998) in 68 patients with right-hemispheric stroke. The two differential aspects of the neglect syndrome were assessed by measuring response tendencies resulting from underestimations of the length of left line segments and from hypometric movement execution towards contralesional space, respectively. Perceptual and response bias were orthogonal components of task performance in the Landmark task. Perceptual as well as response bias both explained variance in the performance of standard paper-and-pencil neglect tests. While lesions within middle frontal, inferior parietal and parieto-occipital brain regions were related to perceptual bias, subcortical lesions within the caudate were related to response bias in the Landmark task. Our data suggest that perceptual/attentional and motor/intentional aspects of neglect are independent components of the syndrome with differential neural underpinnings in fronto-parietal and subcortical brain regions.     

Persecutory beliefs, attributions and theory of mind: comparison of patients with paranoid delusions, Asperger's syndrome and healthy controls

Schizophrenia patients with persecutory delusions and patients with Asperger's syndrome were compared using two measures of theory of mind (ToM; the ability to infer mental states in other people), the Hints task, and the Reading the Mind in the Eyes task, and a new measure of attributional style (style of inferring the causes of important events), the Attributional Style Structured Interview (ASSI). Paranoid beliefs were measured using Fenigstien and Vanable's Paranoia Scale (PS). The deluded group had the highest scores on the Paranoia Scale but the scores of the Asperger's group's were higher than those of the controls. Paranoid patients made more external-personal attributions for negative events than the Asperger's and control groups. Both the paranoid and Asperger's groups performed poorly on the ToM tasks compared to the controls. The findings support the hypothesis that both ToM and attributional abnormalities contribute to paranoid delusions. The lack of attributional abnormalities in the Asperger's group suggests that their low-level paranoid symptoms arise as a consequence of different mechanisms than those involved in psychotic delusions.     

Context-dependent reasoning in a cognitive bias task Part II. SPECT activation study

A cognitive bias task (CBT) delineates two different cognitive selection mechanisms in the prefrontal cortex. To identify functional anatomy of context-dependent reasoning, we used technetium-99mhexamethyl- propyleneamine oxime (99mTc HM-PAO) single photon emission computed tomography (SPECT) and statistical parametric mapping. Twelve right-handed men 20-24 years old were instructed to look at a target card and then select the choice card (among two) that they preferred (modified CBT; mCBT). They also selected a choice card 2 weeks later without prior presentation of a target card (control task). In both tasks, 99mTc HM-PAO was injected intravenously about 15 s after initiation of the mCBT or control task. Brain images were obtained using a gamma camera and reconstructed by a UNIX-based workstation. Statistical analysis compared all activated images to control images. Results associated with P values of less than 0.01 (Z score > 2.36) were depicted on T1-weighted magnetic resonance images. All subjects preferred choices more similar to the target. SPECT activation occurred bilaterally in the dorsolateral prefrontal cortices and middle temporal gyri during performance of the CBT. Additionally, the left inferior prefrontal cortex and left fusiform gyrus showed significant activation compared with the control task. A neural network linking the temporal and prefrontal cortices prominently seen in the left hemisphere participates in context-dependent reasoning. Knowledge of such neural systems is essential for understanding prefrontal lobe function and dysfunction.     

Interstimulus contingency facilitates saccadic responses in a bimodal go/no-go task

The saccadic response to a suddenly appearing visual target stimulus is faster when an accessory auditory stimulus is presented in its spatiotemporal proximity. This multisensory facilitation of reaction time is usually considered a mandatory bottom-up process. Here, we report that it can be modulated by the predictability of the target location provided by an accessory stimulus, thereby indicating a form of top-down processing. Subjects were asked to make a saccade in the direction of a visual target randomly appearing left or right from fixation. An accessory auditory stimulus was presented either at the same location or opposite to the target, with the probability varying over blocks of presentation. Thus, the auditory stimulus contained probabilistic information about the target location (interstimulus contingency). A certain percentage of the trials were catch trials in which the auditory accompanying stimulus (Experiment 1) or the visual target (Experiment 2) was presented alone and the subjects were asked to withhold their response. In particular with visual catch trials, varying the predictability of target location resulted in reaction time facilitation in the bimodal trials, with both high (80%) and low predictability (20%), but only when both stimuli were presented within a small time window (40 ms). As subjects could not possibly follow the task instructions in this short period explicitly, we conclude that they utilized the interstimulus contingency information implicitly, thus revealing an extremely fast involuntary top-down control on saccadic eye movements.     

Impaired cardiac modulation in patients with functional seizures: Results from a face intensity judgment task

Objective

Although interoceptive abnormality in patients with functional seizure (FSs) has been demonstrated using explicit tasks, implicit measurements of interoception such as the effect of interoception on perceptual brain processes have not been investigated. It has been shown that perception is normally modulated by interoceptive signals related to the different phases (systole vs diastole) of the cardiac cycle (cardiac modulation effect). Given our previous findings using explicit measures of interoception, we hypothesized that cardiac modulation would be impaired in FSs.

Methods

Thirty-two patients with FSs and 30 age- and sex-matched non-clinical individuals conducted a face intensity judgment task, in which their intensity rating when fearful or neutral faces was presented was compared between systolic and diastolic phases. They also conducted the heartbeat discrimination task as a measure of their capacity to integrate both interoceptive and exteroceptive information.

Results

Patients with FSs had impaired cardiac modulation of the perception of neutral faces (corrected p = .044). Individual differences in the heartbeat discrimination task predicted the degree to which cardiac modulation occurred across the whole group (p = .028). This cardiac modulation effect was significantly associated with seizure severity (p = .021). Regardless of cardiac phase, patients rated fearful facial expressions as less intense compared to control participants (p = .006).

Significance

These findings highlight impaired implicit cardiac modulation effects in patients with FSs. This reflects interoceptive dysfunction in patients with FSs, and an inability of the brain to integrate interoceptive signaling with perceptual processing. This may have implications for our understanding of the pathophysiology in FSs and inform novel diagnostic approaches.     

A negative emotional and economic judgment bias in major depression

Although major depression is projected to be among the top three causes of disability-adjusted life years lost in 2030, relatively little is known concerning the extent to which depressed mood states can bias social–economic decision making away from optimal outcomes. One experimental framework to study the interaction between negative emotion and social–economic decisions is the ultimatum game (UG), where the fair, cooperative player altruistically punishes the unfair, non-cooperative player. To assess a potential susceptibility of altruistic punishment to depressed mood, we repeatedly administered the UG task to a cohort of 20 currently depressed patients with a diagnosis of recurrent major depressive disorder and 20 healthy controls. Furthermore, valence and arousal ratings of emotionally laden pictures were obtained from all participants in order to assess a depressed mood-related distortion of emotion judgments. Compared to healthy controls, depressed patients over-sanctioned unfair proposals in the UG and judged emotional stimuli too negatively. Thus, major depression is associated with a negative emotional bias that hampers social–economic decision making and produces large personal costs.     

Electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task.

OBJECTIVE: The aim was to verify the occurrence of proposed electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task and to support their functional interpretation by using a manipulation intended to enhance subjects' response bias. METHODS: Electroencephalographic activity was recorded during administration of a transformed version of the AX continuous performance task in which cues signaled response alternatives. RESULTS: The previously reported parietal P3, NoGo-N2, NoGo-P3 and contingent negative variation were replicated. Besides, the frontal selection positivity and the lateralized readiness potential were demonstrated. With increasing Go-probability, the parietal P3 to the cue increased without changes in other cue-related correlates. In addition, reaction times decreased, non-parametric measures of sensitivity and bias decreased, the NoGo-N2 increased, and the parietal Go-P3 decreased. CONCLUSIONS: The proposed electrophysiological correlates were identified. Sub-threshold LRPs suggested a central inhibition mechanism. Cue-related correlates revealed that anticipation of a high-probability Go-stimulus involves attention rather than bias. This implies that the increased NoGo-N2 reflected an increase in conflict rather than an increase in inhibition. SIGNIFICANCE: Electrophysiological measures can greatly enhance our understanding of normal and abnormal information processing during continuous performance and related tasks.     

The contribution of a cognitive bias against disconfirmatory evidence (BADE) to delusions in schizophrenia

A neuropsychological paradigm is introduced that provides a measure of a bias against disconfirmatory evidence (BADE), and its correspondence with delusions in people with schizophrenia and schizoaffective disorder was investigated. Fifty-two patients diagnosed with schizophrenia or schizoaffective disorder (36 were acutely delusional) and 24 healthy control participants were presented with delusion-neutral pictures in each trial, and were asked to rate the plausibility of four written interpretations of the scenario depicted by that picture. Subsequently, new pictures that provided background information about the depicted scenario were successively presented, and participants were requested to adjust their ratings, taking into account this new information. Two of the interpretations appeared tenable initially but ultimately proved to be implausible, one appeared untenable initially but eventually proved to be plausible, and one appeared untenable at all stages. A BADE was observed for delusional compared to non-delusional patients, as well as for all patients compared to controls. In addition, regardless of symptom profile, patients were more accepting of implausible interpretations than controls. The present work suggests that deficits in reasoning may contribute to the maintenance of delusions via an impairment in the processing of disconfirmatory evidence.     

Age shifts frontal cortical control in a cognitive bias task from right to left: part I. Neuropsychological study

Two functionally and neurally distinct cognitive selection mechanisms involve the prefrontal lobes: those based on internal representations (context dependent) and those involving exploratory processing of novel situations (context independent). We used a cognitive bias task (CBT) representing contextual reasoning to correlate lateralization with age in the frontal lobes. Subjects included 37 healthy right-handed male children and adolescents (age range, 5–18 years). Controls were 19 right-handed men from 20 to 30 years old. A computer-presented version of the original card-choice task simplified, modified for children was used (modified CBT; mCBT). Simple visual stimuli differed dichotomously in shape, color, number, and shading. A target object presented alone was followed by two choices from which subjects selected according to preference. Considering all four characteristics, similarity between target and subject choice was scored for 30 trials. A high score implied a context-dependent response selection bias and a low score, a context-independent bias. Similarity increased significantly with age. The youngest children (5–7 years) scored lower than ages from 11 years to adulthood. Between 7 and 9 years, scores began to increase with age to reach an adult level by age 13–16. Young children showed context-independent responses representing right frontal lobe function, while adolescents and adults showed context-dependent responses implicating left frontal lobe function. The locus of frontal cortical control in right-handed male subjects thus shifts from right to left as cognitive contextual reasoning develops.