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Background: Prevalence estimates for body-focused repetitive behaviors (BFRBs) such as trichotillomania differ greatly across studies owing to several confounding factors (e.g. different criteria). For the present study, we recruited a diverse online sample to provide estimates for nine subtypes of BFRBs and body-focused repetitive disorders (BFRDs). Methods: The final sample comprised 1481 individuals from the general population. Several precautions were taken to recruit a diverse sample and to exclude participants with low reliability. We matched participants on gender, race, education and age range to allow unbiased interpretation. Results: While almost all participants acknowledged at least one BFRB in their lifetime (97.1%), the rate for BFRDs was 24%. Nail biting (11.4%), dermatophagia (8.7%), skin picking (8.2%), and lip-cheek biting (7.9%) were the most frequent BFRDs. Whereas men showed more lifetime BFRBs, the rate of BFRDs was higher in women than in men. Rates of BFRDs were low in older participants, especially after the age of 40. Overall, BFRBs and BFRDs were more prevalent in White than in non-White individuals. Education did not show a strong association with BFRB/BFRDs. Discussion: BFRBs are ubiquitous. More severe forms, BFRDs, manifest in approximately one out of four people. In view of the often-irreversible somatic sequelae (e.g. scars) BFRBs/BFRDs deserve greater diagnostic and therapeutic attention by clinicians working in both psychology/psychiatry and somatic medicine (especially dermatology and dentistry). [ABSTRACT FROM AUTHOR]

Kurt Schneider has played a leading role in shaping our current view of schizophrenia, placing certain manifestations of delusions and hallucinations at the center of the disorder, especially ideas of persecution and voice-hearing. The first part of this review summarizes Schneider's original ideas and then traces how the different editions of the DSM merged aspects of Kraepelin's, Bleuler's, and Schneider's historical concepts. Special attention is given to the transition from the DSM-IV to the DSM-5, which eliminated much of Schneider's original concept. In the second part of the article, we contrast the current definition of hallucination in the DSM-5 with that of Schneider. We present empirically derived arguments that favor a redefinition of hallucinations, much in accordance with Schneider's original ideas. We plea for a two-dimensional model of hallucinations that represents the degree of insight and perceptuality, ranging from thoughts with full "mineness" via perception-laden thoughts and intrusions (including "as if" experiences") to hallucinations. While we concur with the DSM-5 that cognitions that are indistinguishable from perceptions should be labeled as hallucinations, we suggest expanding the definition to internally generated sensory phenomena, including those with only partial resemblance to external perceptions, that the individual considers real and that may lie at the heart of a subsequent delusional superstructure. [ABSTRACT FROM AUTHOR]

Background: Various neurocognitive models explore perceptual distortions and hallucinations in schizophrenia and the general population. A variant of predictive coding account suggests that strong priors, like cognitive expectancy, may influence perception. This study examines if stronger cognitive expectancies result in more auditory false percepts in clinical and healthy control groups, investigates group differences, and explores the association between false percepts and hallucinations., Study Design: Patients diagnosed with schizophrenia with current auditory hallucinations (n = 51) and without hallucinations (n = 66) and healthy controls (n = 51) underwent the False Perception Task under various expectancy conditions. All groups were examined for the presence and severity of hallucinations or hallucinatory-like experiences., Study Results: We observed a main effect of condition across all groups, ie, the stronger the cognitive expectancy, the greater the ratio of auditory false percepts. However, there was no group effect for the ratio of auditory false percepts. Despite modest pairwise correlations in the hallucinating group, the ratio of auditory false percepts was not predicted by levels of hallucinations and hallucinatory-like experiences in a linear mixed model., Conclusions: The current study demonstrates that strong priors in the form of cognitive expectancies affect perception and play a role in perceptual disturbances. There is also a tentative possibility that overreliance on strong priors may be associated with hallucinations in currently hallucinating subjects. Possible, avoidable confounding factors are discussed in detail., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)