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Dive into the research topics where Eugenia Kravariti is active.

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Featured researches published by Eugenia Kravariti.


Human Molecular Genetics | 2011

Disease-associated epigenetic changes in monozygotic twins discordant for schizophrenia and bipolar disorder

Emma Dempster; Ruth Pidsley; Leonard C. Schalkwyk; Sheena Owens; Anna Georgiades; Fergus Kane; Sridevi Kalidindi; Marco Picchioni; Eugenia Kravariti; Timothea Toulopoulou; Robin M. Murray; Jonathan Mill

Studies of the major psychoses, schizophrenia (SZ) and bipolar disorder (BD), have traditionally focused on genetic and environmental risk factors, although more recent work has highlighted an additional role for epigenetic processes in mediating susceptibility. Since monozygotic (MZ) twins share a common DNA sequence, their study represents an ideal design for investigating the contribution of epigenetic factors to disease etiology. We performed a genome-wide analysis of DNA methylation on peripheral blood DNA samples obtained from a unique sample of MZ twin pairs discordant for major psychosis. Numerous loci demonstrated disease-associated DNA methylation differences between twins discordant for SZ and BD individually, and together as a combined major psychosis group. Pathway analysis of our top loci highlighted a significant enrichment of epigenetic changes in biological networks and pathways directly relevant to psychiatric disorder and neurodevelopment. The top psychosis-associated, differentially methylated region, significantly hypomethylated in affected twins, was located in the promoter of ST6GALNAC1 overlapping a previously reported rare genomic duplication observed in SZ. The mean DNA methylation difference at this locus was 6%, but there was considerable heterogeneity between families, with some twin pairs showing a 20% difference in methylation. We subsequently assessed this region in an independent sample of postmortem brain tissue from affected individuals and controls, finding marked hypomethylation (>25%) in a subset of psychosis patients. Overall, our data provide further evidence to support a role for DNA methylation differences in mediating phenotypic differences between MZ twins and in the etiology of both SZ and BD.


American Journal of Psychiatry | 2010

Specific and Generalized Neuropsychological Deficits: A Comparison of Patients With Various First-Episode Psychosis Presentations

Jolanta Zanelli; Abraham Reichenberg; Kevin Morgan; Paul Fearon; Eugenia Kravariti; Paola Dazzan; Craig Morgan; Caroline Zanelli; Arsime Demjaha; Peter B. Jones; Gillian A. Doody; Shitij Kapur; Robin M. Murray

OBJECTIVE Overwhelming evidence suggests that compromised neuropsychological function is frequently observed in schizophrenia. Neurocognitive dysfunction has often been reported in other psychotic disorders, although there are inconsistencies in the literature. In the context of four distinct diagnostic groups, the authors compared neuropsychological performance among patients experiencing their first psychotic episode. METHOD Data were derived from a population-based, case-control study of patients with first-episode psychosis. A neuropsychological test battery was administered to patients with a diagnosis of schizophrenia (N=65), bipolar disorder or mania (N=37), depressive psychosis (N=39), or other psychotic disorders (N=46) following index presentation, as well as to healthy comparison subjects (N=177). The presence of specific and generalized cognitive deficits was examined. RESULTS The schizophrenia group presented widespread neuropsychological impairments and performed significantly worse than healthy comparison subjects on most neuropsychological measures. Patients with other psychotic disorders and depressive psychosis also demonstrated widespread impairments. Deficits in patients with bipolar disorder or mania were less pervasive but evident in performance scores on verbal memory and fluency tests. Differences between the four patient groups and healthy comparison subjects and among the patient groups were attenuated after controlling for differences in general cognitive ability (IQ). CONCLUSIONS Early in their course, cognitive deficits are present in all psychotic disorders but are most severe and pervasive in schizophrenia and least pervasive in bipolar disorder and mania.


Psychological Medicine | 2004

Effect of symptoms on executive function in bipolar illness

T. Dixon; Eugenia Kravariti; C. D. Frith; Robin M. Murray; Philip McGuire

Background. The relationship between cognitive function and symptomatology in bipolar disorder is unclear. This study assessed executive function during the manic, depressed and remitted stages of bipolar I disorder. Method. Tasks assessing phonological and semantic verbal fluency, the Hayling Sentence Completion Test, the Stroop Neuropsychological Screening Test and the Cognitive Estimates Test were administered to manic ( n =15), depressed ( n =15), and remitted ( n =15) bipolar I patients, and to healthy controls ( n =30). Multiple regression analyses and analyses of covariance were used to identify potential determinants of executive dysfunction in the three bipolar groups. Results. Executive function deficits were particularly associated with the manic state. In general, manic patients performed less accurately than the remitted and depressed groups, and their performance deficit was related to the severity of positive thought disorder. The depressed and remitted bipolar groups showed a less widespread pattern of impairment. Deficits in response initiation, strategic thinking and inhibitory control were evident in all the bipolar groups. Conclusions. Executive function deficits in bipolar I disorder are most evident during mania, and are particularly associated with formal thought disorder. However, deficits in response initiation, strategic thinking and inhibitory control may be more related to the underlying disorder than a particular symptom profile.


BMC Psychiatry | 2011

Pattern of neural responses to verbal fluency shows diagnostic specificity for schizophrenia and bipolar disorder

Sergi G. Costafreda; Cynthia H.Y. Fu; Marco Picchioni; Timothea Toulopoulou; Colm McDonald; Eugenia Kravariti; Muriel Walshe; Diana Prata; Robin M. Murray; Philip McGuire

BackgroundImpairments in executive function and language processing are characteristic of both schizophrenia and bipolar disorder. Their functional neuroanatomy demonstrate features that are shared as well as specific to each disorder. Determining the distinct pattern of neural responses in schizophrenia and bipolar disorder may provide biomarkers for their diagnoses.Methods104 participants underwent functional magnetic resonance imaging (fMRI) scans while performing a phonological verbal fluency task. Subjects were 32 patients with schizophrenia in remission, 32 patients with bipolar disorder in an euthymic state, and 40 healthy volunteers. Neural responses to verbal fluency were examined in each group, and the diagnostic potential of the pattern of the neural responses was assessed with machine learning analysis.ResultsDuring the verbal fluency task, both patient groups showed increased activation in the anterior cingulate, left dorsolateral prefrontal cortex and right putamen as compared to healthy controls, as well as reduced deactivation of precuneus and posterior cingulate. The magnitude of activation was greatest in patients with schizophrenia, followed by patients with bipolar disorder and then healthy individuals. Additional recruitment in the right inferior frontal and right dorsolateral prefrontal cortices was observed in schizophrenia relative to both bipolar disorder and healthy subjects. The pattern of neural responses correctly identified individual patients with schizophrenia with an accuracy of 92%, and those with bipolar disorder with an accuracy of 79% in which mis-classification was typically of bipolar subjects as healthy controls.ConclusionsIn summary, both schizophrenia and bipolar disorder are associated with altered function in prefrontal, striatal and default mode networks, but the magnitude of this dysfunction is particularly marked in schizophrenia. The pattern of response to verbal fluency is highly diagnostic for schizophrenia and distinct from bipolar disorder. Pattern classification of functional MRI measurements of language processing is a potential diagnostic marker of schizophrenia.


Research in Developmental Disabilities | 2010

Challenging behavior and co-morbid psychopathology in adults with intellectual disability and autism spectrum disorders

Jane McCarthy; Colin Hemmings; Eugenia Kravariti; Katharina Dworzynski; Geraldine Holt; Nick Bouras; Elias Tsakanikos

We investigated the relationship between challenging behavior and co-morbid psychopathology in adults with intellectual disability (ID) and autism spectrum disorders (ASDs) (N=124) as compared to adults with ID only (N=562). All participants were first time referrals to specialist mental health services and were living in community settings. Clinical diagnoses were based on ICD-10 criteria and presence of challenging behavior was assessed with the Disability Assessment Schedule (DAS-B). The analyses showed that ASD diagnosis was significantly associated with male gender, younger age and lower level of ID. Challenging behavior was about four times more likely in adults with ASD as compared to non-ASD adults. In those with challenging behavior, there were significant differences in co-morbid psychopathology between ASD and non-ASD adults. However, after controlling for level of ID, gender and age, there was no association between co-morbid psychopathology and presence of challenging behavior. Overall, the results suggest that presence of challenging behavior is independent from co-morbid psychopathology in adults with ID and ASD.


Psychiatric Services | 2012

Text Message Reminders of Appointments: A Pilot Intervention at Four Community Mental Health Clinics in London

Hannah Sims; Harpreet Sanghara; Daniel Hayes; Symon Wandiembe; Matthew Finch; Hanne Jakobsen; Elias Tsakanikos; Chike Okocha; Eugenia Kravariti

OBJECTIVE Forgetting is commonly stated as a reason for missing mental health appointments. The authors examined the effect of short message service (SMS), or text message, reminders on the attendance of appointments at four community mental health clinics in London. METHODS Attendance of outpatient appointments roughly between March and June of 2008 (N=648), 2009 (N=1,081), and 2010 (N=1,088) was examined. Reminder messages were sent seven and five days before an appointment in 2009 and seven and three days before an appointment in 2010; patients in the 2008 sample received no reminder messages. Appointment attendance during the sample periods was compared by using multiple logistic regression analysis and adjusting for sociodemographic and clinical confounders. RESULTS Missed appointments accounted for 36% of appointments in 2008, 26% of appointments in 2009, and 27% of appointments in 2010. The relative risk reduction in failed attendance was 28% between the 2008 and 2009 samples and 25% between the 2008 and 2010 samples. Attendance rates were significantly higher for the 2009 and 2010 samples than for the 2008 sample (p<.001) but did not differ between the two intervention periods. CONCLUSIONS SMS-based technology can offer a time-, labor-, and cost-efficient strategy for encouraging engagement with psychiatric outpatient services. In England alone, a reduction of 25% to 28% in missed outpatient clinic appointments would translate to national cost savings of more than £150 million, or


Schizophrenia Research | 1998

The Maudsley Early-Onset Schizophrenia Study: cognitive function in adolescent-onset schizophrenia

Eugenia Kravariti; Robin G. Morris; Sophia Rabe-Hesketh; Robin M. Murray; Sophia Frangou

245 million, per year, and likely have clinical benefits as well.


Schizophrenia Research | 2003

The Maudsley early onset schizophrenia study: cognitive function in adolescents with recent onset schizophrenia

Eugenia Kravariti; Robin G. Morris; Sophia Rabe-Hesketh; Robin M. Murray; Sophia Frangou

The neuropsychological correlates of adolescent-onset schizophrenia have been investigated very little to date. We assessed intelligence, memory and executive function in 42 patients with adolescent-onset schizophrenia and 43 healthy control subjects. Cases showed impairments in most cognitive variables. Despite the overall similarity with the quantitative and qualitative performance characteristics of later-onset patients in the literature, their cognitive profile displayed a unique feature: modification of the usual pattern of thinking latencies in the Tower of London Task. After adjusting for potential confounders, no effect of illness duration, symptoms or medication dose on patient performance emerged. However, longer exposure to medication predicted a lower level of performance in aspects of attention, psychomotor processing speed and spatial working memory. Our data are not consistent with worse cognition or progression of neuropsychological impairment in adolescent-onset schizophrenia.


Psychological Medicine | 2007

Genetic overlap between bipolar illness and event-related potentials

Mei-Hua Hall; Fruhling Rijsdijk; Sridevi Kalidindi; Katja Schulze; Eugenia Kravariti; Fergus Kane; Pak Sham; Elvira Bramon; Robin M. Murray

Neuropsychological function has been little studied early in the course of adolescent onset schizophrenia. The present study investigated cognitive function in adolescents with recent onset schizophrenia (n=20) and healthy controls (n=21), employing a comprehensive battery of intelligence, memory and executive function paradigms. Relative to the control group, the patients showed significant or near-significant deficits in more than half of the cognitive variables we examined. A substantial proportion of this broadly based neuropsychological deficit could be accounted for, at least in part, by a mild decrement in general intellectual ability. However, deficits in general and verbal memory remained highly significant after co-varying for IQ.


Biological Psychiatry | 2009

Opposite Effects of Catechol-O-Methyltransferase Val158Met on Cortical Function in Healthy Subjects and Patients with Schizophrenia

Diana Prata; Andrea Mechelli; Cynthia H.Y. Fu; Marco Picchioni; Fergus Kane; Sridevi Kalidindi; Colm McDonald; Oliver Howes; Eugenia Kravariti; Arsime Demjaha; Timothea Toulopoulou; Marta DiForti; Robin M. Murray; David A. Collier; Philip McGuire

BACKGROUND Electrophysiological endophenotypes are far less explored in bipolar disorder as compared to schizophrenia. No previous twin study of event-related potentials (ERPs) in bipolar illness has been reported. This study uses a twin design and advanced genetic model fitting analyses aiming to (1) assess and quantify the relationship of a range of ERP components with bipolar disorder with psychotic features, and (2) examine the source of the relationship (due to genetic or environmental factors). METHOD P300, P50 suppression and mismatch negativity (MMN) were recorded in 10 discordant monozygotic (MZ) bipolar twin pairs, six concordant MZ bipolar twin pairs and 78 control twin pairs. Statistical analyses were based on structural equation modelling. RESULTS Bipolar disorder was significantly associated with smaller P300 amplitude and decreased P50 suppression. Genetic correlations were the main source of the associations, estimated to be -0 x 33 for P300 amplitude and 0 x 46 for P50 ratio. Individual-specific environmental influences were not significant. MMN and P300 latency were not associated with the illness. CONCLUSIONS The results provide supporting evidence that P300 amplitude and P50 suppression ratio are ERP endophenotypes for bipolar disorder.

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Colm McDonald

National University of Ireland

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Elvira Bramon

University College London

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