Kathryn Greenwood

A modified fuzzy clustering algorithm for operator independent brain tissue classification of dual echo MR images

Methods for brain tissue classification or segmentation of structural magnetic resonance imaging (MRI) data should ideally be independent of human operators for reasons of reliability and tractability. An algorithm is described for fully automated segmentation of dual echo, fast spin-echo MRI data. The method is used to assign fuzzy-membership values for each of four tissue classes (gray matter, white matter, cerebrospinal fluid and dura) to each voxel based on partition of a two dimensional feature space. Fuzzy clustering is modified for this application in two ways. First, a two component normal mixture model is initially fitted to the thresholded feature space to identify exemplary gray and white matter voxels. These exemplary data protect subsequently estimated cluster means against the tendency of unmodified fuzzy clustering to equalize the number of voxels in each class. Second, fuzzy clustering is implemented in a moving window scheme that accommodates reduced image contrast at the axial extremes of the transmitting/receiving coil. MRI data acquired from 5 normal volunteers were used to identify stable values for three arbitrary parameters of the algorithm: feature space threshold, relative weight of exemplary gray and white matter voxels, and moving window size. The modified algorithm incorporating these parameter values was then used to classify data from simulated images of the brain, validating the use of fuzzy-membership values as estimates of partial volume. Gray:white matter ratios were estimated from 20 twenty normal volunteers (mean age 32.8 years). Processing time for each three-dimensional image was approximately 30 min on a 170 MHz workstation. Mean cerebral gray and white matter volumes estimated from these automatically segmented images were very similar to comparable results previously obtained by operator dependent methods, but without their inherent unreliability.

Domains of Awareness in Schizophrenia

Patients with schizophrenia are often characterized as lacking insight or awareness into their illness and symptoms, yet despite considerable research, we still lack a full understanding of the factors involved in causing poor awareness. Within schizophrenia, there has been shown to be a fractionation across dimensions of awareness into mental illness: of being ill, of symptoms, and of treatment compliance. Recently, attention has turned to evidence of a fractionation between awareness of illness and of cognitive impairments and functioning. The current study investigated the degree of fractionation across a broad range of domains of function in schizophrenia and how each domain may be associated with neuropsychological functioning, clinical, mood, and demographic variables. Thirty-one mostly chronic stable patients with schizophrenia completed a battery of neuropsychological tests and measures of psychopathology, including mood. Cognitive insight and awareness of illness, symptoms, memory, and behavioral functioning were also measured. Insight and awareness were assessed using a combination of semistructured interview, observer-rated, self-rated, and objective measures, and included measures of the discrepancy between carer and self-ratings of impairment. Results revealed that awareness of functioning in each domain was largely independent and that awareness in each domain was predicted by different factors. Insight into symptoms was relatively poor while insight into cognitive deficits was preserved. Relative to neuropsychological variables, cognitive insight, comprising self-certainty and self-reflexivity, was a greater predictor of awareness. In conclusion, awareness is multiply fractionated and multiply determined. Therapeutic interventions could, therefore, produce beneficial changes within specific domains of awareness.

CHoice of Outcome In Cbt for psychosEs (CHOICE): The Development of a New Service User–Led Outcome Measure of CBT for Psychosis

Outcome measures for cognitive behavior therapy for psychosis (CBTp) have been derived from pharmacological studies, focusing on symptom change rather than outcomes such as distress or fulfillment. This study presents the development and psychometric properties of a new outcome measure (CHoice of Outcome In Cbt for psychosEs [CHOICE]), which reflects more strongly the aims of CBTp and the priorities of service users. Service users who had received CBTp participated in focus groups to discuss their outcome priorities, using a topic guide generated by a panel of experts in CBTp. A qualitative thematic analysis was undertaken to reach consensus on themes and generate items. Response scales were constructed for 3 dimensions: severity, satisfaction, and importance. The resulting questionnaire was piloted with service users who had not received CBTp, stratified by service type, ethnicity, and first language to ensure that it was user friendly and applicable prior to CBTp. The psychometric properties of the measure were then examined in a sample of 152 service users. Twenty-four items, and 2 of the dimensions (severity and satisfaction), were retained in the final measure. A factor analysis revealed a single psychological recovery factor interspersed throughout with both CBTp and recovery items. Test-retest reliability, construct validity, and sensitivity to change following CBTp were confirmed. The CHOICE measure is unique in being the first psychometrically adequate service user-led outcome measure of CBTp. It provides the opportunity to examine the evidence base for CBTp with an assessment approach that prioritizes service user definitions of recovery and CBT aims.

Cardiovascular risk factors and metabolic syndrome in people with established psychotic illnesses: baseline data from the IMPaCT randomized controlled trial.

Background The aims of the study were to determine the prevalence of cardiometabolic risk factors and establish the proportion of people with psychosis meeting criteria for the metabolic syndrome (MetS). The study also aimed to identify the key lifestyle behaviours associated with increased risk of the MetS and to investigate whether the MetS is associated with illness severity and degree of functional impairment. Method Baseline data were collected as part of a large randomized controlled trial (IMPaCT RCT). The study took place within community mental health teams in five Mental Health NHS Trusts in urban and rural locations across England. A total of 450 randomly selected out-patients, aged 18–65 years, with an established psychotic illness were recruited. We ascertained the prevalence rates of cardiometabolic risk factors, illness severity and functional impairment and calculated rates of the MetS, using International Diabetes Federation (IDF) and National Cholesterol Education Program Third Adult Treatment Panel criteria. Results High rates of cardiometabolic risk factors were found. Nearly all women and most men had waist circumference exceeding the IDF threshold for central obesity. Half the sample was obese (body mass index ≥ 30 kg/m2) and a fifth met the criteria for type 2 diabetes mellitus. Females were more likely to be obese than males (61% v. 42%, p < 0.001). Of the 308 patients with complete laboratory measures, 57% (n = 175) met the IDF criteria for the MetS. Conclusions In the UK, the prevalence of cardiometabolic risk factors in individuals with psychotic illnesses is much higher than that observed in national general population studies as well as in most international studies of patients with psychosis.

Cardiovascular risk factors and metabolic syndrome in people with established psychotic illnesses

Background The aims of the study were to determine the prevalence of cardiometabolic risk factors and establish the proportion of people with psychosis meeting criteria for the metabolic syndrome (MetS). The study also aimed to identify the key lifestyle behaviours associated with increased risk of the MetS and to investigate whether the MetS is associated with illness severity and degree of functional impairment. Method Baseline data were collected as part of a large randomized controlled trial (IMPaCT RCT). The study took place within community mental health teams in five Mental Health NHS Trusts in urban and rural locations across England. A total of 450 randomly selected out-patients, aged 18–65 years, with an established psychotic illness were recruited. We ascertained the prevalence rates of cardiometabolic risk factors, illness severity and functional impairment and calculated rates of the MetS, using International Diabetes Federation (IDF) and National Cholesterol Education Program Third Adult Treatment Panel criteria. Results High rates of cardiometabolic risk factors were found. Nearly all women and most men had waist circumference exceeding the IDF threshold for central obesity. Half the sample was obese (body mass index ≥ 30 kg/m2) and a fifth met the criteria for type 2 diabetes mellitus. Females were more likely to be obese than males (61% v. 42%, p < 0.001). Of the 308 patients with complete laboratory measures, 57% (n = 175) met the IDF criteria for the MetS. Conclusions In the UK, the prevalence of cardiometabolic risk factors in individuals with psychotic illnesses is much higher than that observed in national general population studies as well as in most international studies of patients with psychosis.

Hearing the voices of service user researchers in collaborative qualitative data analysis: the case for multiple coding.

Health research is frequently conducted in multi‐disciplinary teams, with these teams increasingly including service user researchers. Whilst it is common for service user researchers to be involved in data collection – most typically interviewing other service users – it is less common for service user researchers to be involved in data analysis and interpretation. This means that a unique and significant perspective on the data is absent.

An Examination of Polygenic Score Risk Prediction in Individuals With First-Episode Psychosis

BACKGROUND Polygenic risk scores (PRSs) have successfully summarized genome-wide effects of genetic variants in schizophrenia with significant predictive power. In a clinical sample of first-episode psychosis (FEP) patients, we estimated the ability of PRSs to discriminate case-control status and to predict the development of schizophrenia as opposed to other psychoses. METHODS The sample (445 case and 265 control subjects) was genotyped on the Illumina HumanCore Exome BeadChip with an additional 828 control subjects of African ancestry genotyped on the Illumina Multi-Ethnic Genotyping Array. To calculate PRSs, we used the results from the latest Psychiatric Genomics Consortium schizophrenia meta-analysis. We examined the association of PRSs with case-control status and with schizophrenia versus other psychoses in European and African ancestry FEP patients and in a second sample of 248 case subjects with chronic psychosis. RESULTS PRS had good discriminative ability of case-control status in FEP European ancestry individuals (9.4% of the variance explained, p < 10-6), but lower in individuals of African ancestry (R2 = 1.1%, p = .004). Furthermore, PRS distinguished European ancestry case subjects who went on to acquire a schizophrenia diagnosis from those who developed other psychotic disorders (R2 = 9.2%, p = .002). CONCLUSIONS PRS was a powerful predictor of case-control status in a European sample of patients with FEP, even though a large proportion did not have an established diagnosis of schizophrenia at the time of assessment. PRS was significantly different between those case subjects who developed schizophrenia from those who did not, although the discriminative accuracy may not yet be sufficient for clinical utility in FEP.

Sedentary behaviour is associated with elevated C-reactive protein levels in people with psychosis

Psychosis is associated with elevated inflammatory markers including C-reactive protein (CRP), a marker of cardiovascular disease (CVD) risk. Using a cross sectional design, 250 participants with established psychosis (48.2years (SD 10.2), 39.2% female) were classified as having normal (<5.0mg/μl, N=159) or high CRP levels (>5.0mg/μl, N=91). Regression analysis demonstrated that higher sedentary behaviour was associated with elevated CRP levels (β=.155, p=.01) after adjustment for confounding variables. Female gender (β=.229, p=.001), waist circumference (β=.205, p=.003) and non-white ethnicity (β=.181, p=.005) were also associated with elevated CRP. Sedentary behaviour is modifiable and increasing physical activity may reduce CRP levels.

Executive functioning in schizophrenia and the relationship with symptom profile and chronicity

This study reports the executive function profile in people with schizophrenia, with a simultaneous comparison of chronicity and of those with predominately disorganization versus psychomotor poverty symptoms. The patients were split into one set defined according to symptoms (29 with disorganization, 29 with negative symptoms) and the other representing chronicity (22 first-episode, 35 chronic) and compared with 28 healthy controls on a broad range of executive process measures. Differences were investigated in both the severity and profile of impairments. Impairment patterns interacted with symptom groups, with disorganization and psychomotor poverty symptom groups showing different profiles of executive impairment. In contrast, across these same executive processes, impairment profiles were similar between first episode and chronic schizophrenia and became more similar, particularly for working memory, when controlling for disorganization symptoms. The executive profile, therefore, is related to symptom type rather than chronicity.

No association between the Catechol-O-Methyltransferase (COMT) val158met polymorphism and cognitive improvement following cognitive remediation therapy (CRT) in schizophrenia

Cognitive deficits are rate limiters on recovery in schizophrenia that respond poorly to pharmacotherapy. Cognitive remediation therapy (CRT), a novel psychological therapy, has produced promising outcomes for cognition. However, little is known about the biological mechanisms that might underlie individual differences in CRT response. Catechol-O-Methyltransferase (COMT) is associated specifically with prefrontal cognition. The COMT Val158Met polymorphism is known to have a functional effect on the rate of dopamine degradation, which may be related to cognitive treatment response. This study aimed to determine whether COMT genotype influences cognitive improvement following CRT in schizophrenia. Participants with schizophrenia were recruited from three randomised controlled trials of CRT compared to treatment as usual, and one CRT treatment only trial, each providing 40 CRT sessions. Eighty-seven participants (40%) agreed to participate in the genetic study, and provided DNA for COMT genotyping. Cognitive function and psychopathology were assessed at baseline, post-treatment and 3-6-month follow-up. People with the COMT Val/Met genotype performed more poorly on categories achieved at baseline on the Wisconsin Card Sorting Test (WCST) than those homozygous for the Val or Met allele. Cognitive function improved with CRT but there was no association between this cognitive improvement and COMT genotype, either in the CRT group or in the total sample. The COMT val158Met polymorphism does not appear to be a clinically useful biomarker of cognitive improvement following CRT in schizophrenia. A complex set of factors may influence cognitive change, however, such that the COMT genotype might still have a subtle effect on response to CRT or similar interventions.