Inside the mind of poor Tom--A multidimensional approach to determine causes for redundant clothing in patients with schizophrenia

Self-monitoring in schizophrenia: Weighting exteroceptive visual signals against self-generated vestibular cues

Disturbances in self-monitoring are core symptoms of schizophrenia. Some research suggests an over-reliance on exteroceptive cues and a reduced weighting of self-generated interoceptive signals to guide perception. The vestibular sense provides important self-generated information about the body in space. Alterations of vestibular function are reported in schizophrenia, but it is unknown whether internally generated vestibular information is discounted in favour of exteroceptive input. In this study, we test for evidence of an over-reliance on exteroceptive visual cues and a reduced weighting of vestibular signals in guiding perception. In a group of individuals with schizophrenia and healthy controls, we used a well-studied visual illusion - the Tilt Illusion - to probe the respective weight given to visual and vestibular cues in judging line orientation. The Tilt Illusion reveals that perceived orientation of a vertical grating is biased by the orientation in its surround. This illusion increases when the head is tilted, due to the reduced reliability of vestibular information that would otherwise provide an internally generated reference for vertical. We predicted that an over-reliance on exteroceptive cues in schizophrenia would lead to a reduced susceptibility to the effects of head position on Tilt Illusion strength. We find no difference between patients and controls. Both groups show comparable Tilt Illusion magnitudes that increase when the head is tilted. Thus, our findings suggest that chronic patients with schizophrenia adequately combine self-generated vestibular cues and exteroceptive visual input to judge line verticality. A stronger reliance on exteroceptive information over internally generated signals in guiding perception is not evident in our data. Deficits in self-monitoring might therefore be modality specific or state dependant.

The Epigenetics of Psychosis: A Structured Review with Representative Loci

The evidence for an environmental component in chronic psychotic disorders is strong and research on the epigenetic manifestations of these environmental impacts has commenced in earnest. In reviewing this research, the focus is on three genes as models for differential methylation, MCHR1, AKT1 and TDO2, each of which have been investigated for genetic association with psychotic disorders. Environmental factors associated with psychotic disorders, and which interact with these model genes, are explored in depth. The location of transcription factor motifs relative to key methylation sites is evaluated for predicted gene expression results, and for other sites, evidence is presented for methylation directing alternative splicing. Experimental results from key studies show differential methylation: for MCHR1, in psychosis cases versus controls; for AKT1, as a pre-existing methylation pattern influencing brain activation following acute administration of a psychosis-eliciting environmental stimulus; and for TDO2, in a pattern associated with a developmental factor of risk for psychosis, in all cases the predicted expression impact being highly dependent on location. Methylation induced by smoking, a confounding variable, exhibits an intriguing pattern for all three genes. Finally, how differential methylation meshes with Darwinian principles is examined, in particular as it relates to the "flexible stem" theory of evolution.

Interoception abnormalities in schizophrenia: A review of preliminary evidence and an integration with Bayesian accounts of psychosis

Schizophrenia research has traditionally focused almost exclusively on how the brain interprets the outside world. However, our internal bodily milieu is also central to how we interpret the world and construct our reality: signals from within the body are critical for not only basic survival, but also a wide range of brain functions from basic perception, emotion, and motivation, to sense of self. In this article, we propose that interoception-the processing of bodily signals-may have implications for a wide range of clinical symptoms in schizophrenia and may thus provide key insights into illness mechanisms. We start with an overview of interoception pathways. Then we provide a review of direct and indirect findings in various interoceptive systems in schizophrenia and interpret these findings in the context of computational frameworks that model interoception as hierarchical Bayesian inference. Finally, we propose a conceptual model of how altered interoceptive inference may contribute to specific schizophrenia symptoms-negative symptoms in particular-and suggest directions for future research, including potential new avenues of treatment.

Interview and questionnaire assessment of cognitive impairment in subjects at ultra-high risk for psychosis: Associations with cognitive test performance, psychosocial functioning, and positive symptoms

Impaired cognitive test performance is well-documented in subjects at ultra-high risk (UHR) for psychosis. However, assessment of cognitive deficits as manifested in real life is a neglected area of UHR research that may add to the understanding of cognitive impairment and its relationship with psychosocial functioning and positive symptomatology. This study applied the interview-based Schizophrenia Cognition Rating Scale (SCoRS) and the questionnaire-based Behavior Rating Inventory of Executive Function - Adult Version (BRIEF-A) in a cross-sectional sample of 39 UHR subjects and 50 healthy controls. Cognitive test performance, psychosocial functioning, and positive symptoms were also assessed. The UHR subjects demonstrated significant cognitive impairment, with large effect sizes for the SCoRS and BRIEF-A composite outcome variables (rs = -0.67 to -0.80) and a neurocognitive composite score (d = -0.97). Within the UHR group, several significant associations between worse cognitive ratings and worse cognitive test performance (rs = -0.210 to -0.343), poorer psychosocial functioning (rs = -0.058 to -0.728), and worse positive symptoms (rs= 0.415 to 0.478) were found. Worse cognitive test performance showed significant associations with more pronounced positive symptoms (rs = -0.299 to -0.457). Interview and questionnaire assessment may hold promise for supplementing traditional performance-based cognitive assessment in identifying treatment targets in the UHR population.

Lipids, aggression, suicidality and impulsivity in drug-naïve/drug-free patients of schizophrenia

AIM

Present study aimed at determining lipid profiles in acutely symptomatic drug-naïve/drug-free patients of schizophrenia, comparing them with healthy controls and exploring relationships between various lipid fractions, aggression, suicidality and impulsivity in this population.

MATERIALS AND METHODS

This was a cross-sectional hospital-based study, comparing patients with schizophrenia (M=46, F=14; mean age 32.40±6.6 years; 48 drug-free for 10.50±9.2 weeks) with 60 age-sex matched healthy controls. Upon recruitment, fasting venous blood samples of all subjects were analysed for total cholesterol, HDL, LDL, VLDL and TG levels, and patients were rated on PANSS for symptom severity, Modified Overt Aggression Scale for aggression, Impulsivity Rating Scale for impulsivity and Scale for Suicide Ideation for suicidality.

RESULTS

The socio-demographic characteristics of the patients were comparable to controls. In patients, total cholesterol, HDL and LDL levels were found to be significantly lower (p<0.01) than the control group. When explored further in patients, lower total cholesterol and LDL levels showed significant negative correlations with scores on impulsivity (p<0.01) and suicidality (p<0.05); and TG level showed a negative correlation with impulsivity (p<0.05).

CONCLUSIONS

This study adds to a growing literature on a complex relationship between lipid fractions and impulsivity, suicidality and aggression in schizophrenia; providing interesting insights into the biochemical basis of human behaviour and confirming these in a developing-world population. The implications are many, including a need to review judiciously the promotion of weight loss and cholesterol reduction programmes in constitutionally vulnerable population, at least during their acutely-symptomatic states.

Identity and schizophrenia: Who do I want to be?

Many individuals with schizophrenia have occasional difficulty defining both to themselves and to others who they truly are. Perhaps for this reason they make attempts to change core aspects of themselves. These attempts may be delusional, but are too often unjustly dismissed as delusional before the potential value of the change is considered. Instead of facilitation, obstacles are placed in the way of hoped-for body modifications or changes of name or of religious faith. This paper discusses the various changes of identity sometimes undertaken by individuals with schizophrenia who may or may not be deluded. Ethical and clinical ramifications are discussed. The recommendation is made that, when clinicians respond to requests for help with identity change, safety needs to be the main consideration.