Shift toward prior knowledge confers a perceptual advantage in early psychosis and psychosis-prone healthy individuals
- Proceedings of the National Academy of Sciences of the United States of America
- Published over 2 years ago
Many neuropsychiatric illnesses are associated with psychosis, i.e., hallucinations (perceptions in the absence of causative stimuli) and delusions (irrational, often bizarre beliefs). Current models of brain function view perception as a combination of two distinct sources of information: bottom-up sensory input and top-down influences from prior knowledge. This framework may explain hallucinations and delusions. Here, we characterized the balance between visual bottom-up and top-down processing in people with early psychosis (study 1) and in psychosis-prone, healthy individuals (study 2) to elucidate the mechanisms that might contribute to the emergence of psychotic experiences. Through a specialized mental-health service, we identified unmedicated individuals who experience early psychotic symptoms but fall below the threshold for a categorical diagnosis. We observed that, in early psychosis, there was a shift in information processing favoring prior knowledge over incoming sensory evidence. In the complementary study, we capitalized on subtle variations in perception and belief in the general population that exhibit graded similarity with psychotic experiences (schizotypy). We observed that the degree of psychosis proneness in healthy individuals, and, specifically, the presence of subtle perceptual alterations, is also associated with stronger reliance on prior knowledge. Although, in the current experimental studies, this shift conferred a performance benefit, under most natural viewing situations, it may provoke anomalous perceptual experiences. Overall, we show that early psychosis and psychosis proneness both entail a basic shift in visual information processing, favoring prior knowledge over incoming sensory evidence. The studies provide complementary insights to a mechanism by which psychotic symptoms may emerge.
The present study examined the validity of psychometrically assessed positive and negative schizotypy in a study of 214 Spanish young adults using interview and questionnaire measures of impairment and psychopathology. Schizotypy provides a useful construct for understanding the etiology and development of schizophrenia and related disorders. Recent interview, laboratory, and experience sampling studies have supported the validity of psychometrically assessed positive and negative symptom dimensions. The present study expands on previous findings by examining the validity of these dimensions in a Spanish sample and employing a widely used interview measure of the schizophrenia prodrome. As hypothesized, the positive schizotypy dimension predicted CAARMS ultra high-risk or psychosis threshold status, and both dimensions uniquely predicted the presence of schizophrenia-spectrum personality disorders. Furthermore, positive schizotypy was associated with psychotic-like, paranoid, schizotypal, and mood symptoms, whereas negative schizotypy was associated with interview ratings of negative and schizoid symptoms. The schizotypy dimensions were also distinguished by their associations with self and other schemas. Positive schizotypy was associated with increased negative self and other schemas, whereas negative schizotypy was associated with decreased positive self and other schemas. The findings provide further construct validation of positive and negative schizotypy and support these dimensions as universal constructs.
Virtual reality in the treatment of persecutory delusions: randomised controlled experimental study testing how to reduce delusional conviction
- The British journal of psychiatry : the journal of mental science
- Published over 1 year ago
Persecutory delusions may be unfounded threat beliefs maintained by safety-seeking behaviours that prevent disconfirmatory evidence being successfully processed. Use of virtual reality could facilitate new learning.
Fregoli delusion is the mistaken belief that some person currently present in the deluded person’s environment (typically a stranger) is a familiar person in disguise. The stranger is believed to be psychologically identical to this known person (who is not present) even though the deluded person perceives the physical appearance of the stranger as being different from the known person’s typical appearance. To gain a deeper understanding of this contradictory error in the normal system for tracking and identifying known persons, we conducted a detailed survey of all the Fregoli cases reported in the literature since the seminal Courbon and Fail (1927) paper. Our preliminary reading of these cases revealed a notable lack of definitional clarity. So, we first formulated a classification scheme of different person misidentification delusions so as to identify those cases that qualified as instances of Fregoli according to the above characterization: the mistaken belief that a known person is present in the environment in a different guise to his or her typical appearance. We identified 38 clear cases of this type and set out to answer a series of questions motivated by current hypotheses about the origin of the Fregoli delusion. We asked whether the patients misidentified particular strangers, made reference to the misidentified known persons using wigs or plastic surgery (or other techniques to disguise their appearance), misidentified many different strangers or only one, showed other symptoms (in particular, other misidentification delusions), and made inferences about the motives of the known persons in disguise. We conclude by discussing the implications of our findings for current hypotheses concerning the origin of the Fregoli delusion.
Sustained antipsychotic effect of metacognitive training in psychosis: A randomized-controlled study
- European psychiatry : the journal of the Association of European Psychiatrists
- Published about 4 years ago
Persistent psychotic symptoms represent a major challenge for psychiatric care. Basic research has shown that psychotic symptoms are associated with cognitive biases. Metacognitive training (MCT) aims at helping patients to become aware of these biases and to improve problem-solving. Fifty-two participants fulfilling diagnostic criteria of schizophrenia or schizoaffective disorders and persistent delusions and stabilized antipsychotic medication were enrolled in this study. Following baseline assessment patients were randomized either to treatment as usual (TAU) conditions or TAU+MCT. The intervention consisted of eight weekly 1-hour sessions (maximum: 8hours). Participants were assessed at 8weeks and 6-months later by blind assessors. Participants were assessed with the Psychotic Symptoms Rating Scales (PSYRATS) and the positive subscale of the PANSS. Between-group differences in post- and pre-test values were significant at a medium effect size in favor of the MCT for the PSYRATS delusion scale and the positive scale of the PANSS both at post and follow-up. The results of this study indicate that MCT training has a surplus antipsychotic effect for patients suffering from schizophrenia-related disorders who demonstrate only a partial response to antipsychotic treatment and that the effect of the intervention persists for at least 6months after the intervention.
- American journal of Alzheimer's disease and other dementias
- Published about 4 years ago
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.
Background: Synthetic cannabinoid (SC) or “spice” refers to a variety of herbal/chemical mixtures, which mimic the effects of marijuana. They are generally marked as “herbal incense” and best known by the brand names of “K2”, “spice”, “aroma”, “Mr. nice guy” and “dream”. Little data is available on the psychopathological and physical effects of SC.Case description: We reported on a 23-year-old man without prior psychiatric history, who developed acute psychosis and severe rhabdomyolysis (CPK: 44,300 UI/L) associated with “Mr. nice guy” consumption. To our knowledge, this is the first case report of severe rhabdomyolysis associated with SC use in the U.S.Conclusion: Physicians should be aware to the possibility of new-onset psychotic symptoms and rhabdomyolysis in patients that use SC.
While the concept of disorders of basic self-experience as the clinical core of schizophrenia spectrum disorders has gained increasing significance and empirical support, several questions remain still unresolved. One major problem is to understand how the basic and prodromal self-disturbances are related to Schneider’s first rank symptoms, in particular to the so-called ‘ego disorders’ found in acute psychotic episodes. The study of the transition from prodromal to first rank symptoms, for example from alienated thoughts to thoughts aloud or thought insertions, is of particular importance for understanding the nature and course of schizophrenia. The paper analyses the emergence of ego disorders from basic self-disorders in phenomenological terms, taking the examples of motor passivity experiences and thought insertion. It is argued that full-blown delusions of alien control are ultimately based on a disturbance of the intentionality of thinking, feeling and acting. This disturbance, for its part, may be traced back to anomalies of self-experience in prodromal stages of schizophrenia.
Measures of social cognition are increasingly being applied to psychopathology, including studies of schizophrenia and other psychotic disorders. Tests of social cognition present unique challenges for international adaptations. The Mayer-Salovey-Caruso Emotional Intelligence Test, Managing Emotions Branch (MSCEIT-ME) is a commonly-used social cognition test that involves the evaluation of social scenarios presented in vignettes.
Patients with psychosis frequently report difficulties getting or staying asleep (insomnia). Dissatisfaction with sleep is high. Insomnia should be treated in this group, but typically it is not even assessed. Importantly, recent evidence indicates that insomnia triggers and exacerbates delusions and hallucinations. The clinical implication is that if the insomnia is treated then the psychotic symptoms will significantly lessen. In a case series with 15 patients with persecutory delusions resistant to previous treatment this is exactly what we found: cognitive behavioural therapy for insomnia (CBT-I) led to large reductions in both the insomnia and delusions. The clear next step is a pilot randomized controlled test. The clinical aim is to test whether CBT-I can reduce both insomnia and psychotic symptoms. The trial will inform decisions for a definitive large-scale evaluation.Methods/designWe will carry out a randomized controlled trial (the Better Sleep Trial, or the BEST study) with 60 patients with distressing delusions or hallucinations in the context of a schizophrenia spectrum diagnosis. Half of the participants will be randomized to receive CBT-I, in addition to their standard treatment, for up to eight sessions over 12 weeks. The other half will continue with treatment as usual. Blind assessments will take place at 0 weeks, 12 weeks (post-treatment) and 24 weeks (follow-up). The primary outcome hypotheses are that CBT-I added to treatment as usual will improve sleep, delusions and hallucinations compared with only treatment as usual. All main analyses will be carried out at the end of the last follow-up assessments and will be based on the intention-to-treat principle. The trial is funded by the NHS National Institute for Health Research (NIHR) Research for Patient Benefit Programme. Data collection will be complete by the end of 2014.