Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Emmanouil Rizos is active.

Publication


Featured researches published by Emmanouil Rizos.


World Journal of Biological Psychiatry | 2008

Reduced serum BDNF levels in patients with chronic schizophrenic disorder in relapse, who were treated with typical or atypical antipsychotics.

Emmanouil Rizos; Athanasia Papadopoulou; Efstathios Laskos; Panagiota G. Michalopoulou; Anastasia N. Kastania; Dimitrios Vasilopoulos; Konstantinos Katsafouros; Lefteris Lykouras

Brain-derived neurotrophic factor signals and dopaminergic function in the brain are strongly associated, and research on BDNF in schizophrenia may enhance our insights on the pathophysiological mechanisms of this disease. In the present study we aimed to investigate the possible association between serum BDNF levels and schizophrenic relapses and the possible differential effects of treatment with typical and atypical antipsychotics on serum BDNF levels in the same group of patients. We measured serum BDNF levels in 47 patients with schizophrenia during a relapse and again 6 weeks after administration of antipsychotic treatment (14 on risperidone, 18 on haloperidol, 10 on olanzapine and five on amisulpride) and in 44 healthy volunteers. Patients with schizophrenia showed reduced serum BDNF levels in relation to healthy volunteers at study entry. No significant differences were revealed in BDNF serum levels after 6 weeks of antipsychotic treatment in the patients compared to their own levels at study entry. However, serum BDNF was significantly increased in the subgroup receiving olanzapine compared to the other antipsychotics. Our findings may indicate a differential effect of olanzapine on BDNF levels compared to haloperidol, risperidone, and amisulpride.


Progress in Neuro-psychopharmacology & Biological Psychiatry | 2008

Investigation of serum BDNF levels in drug-naive patients with schizophrenia

Emmanouil Rizos; Ioannis Rontos; Efstathios Laskos; G. Arsenis; Panagiota G. Michalopoulou; D. Vasilopoulos; Rossetos Gournellis; Lefteris Lykouras

The role of brain-derived neurotrophic factor (BDNF) is to promote and modulate the neuronal responses across neurotransmitter systems in the brain. Therefore, abnormal BDNF signaling may be associated with the pathophysiology of schizophrenia. Decreased BDNF levels in the brain and the serum of patients with psychotic disorders have been reported. In the present study, we assessed serum BDNF levels in a group of 14 drug-naive first-episode patients with schizophrenia (FEP), compared to 15 healthy controls. The serum BDNF levels in the sample of FEP patients was significantly reduced compared to normal controls (23.92+/-5.99 ng/ml vs. 30.0+/-8.43 ng/ml, F=5.01, df=1, p=.034). Negative correlations were shown between serum BDNF levels of the patients and the PANSS Positive and Negative subscale scores. Our findings indicate that BDNF levels at the onset of schizophrenia may reflect associated pathophysiological processes as well as the severity of positive and negative psychotic symptoms.


Schizophrenia Research | 2011

Association of serum BDNF levels with hippocampal volumes in first psychotic episode drug-naive schizophrenic patients

Emmanouil Rizos; Matilda Papathanasiou; Panagiota Michalopoulou; A. Mazioti; A. Douzenis; Anastasia N. Kastania; Paraskevi Nikolaidou; Efstathios Laskos; Konstantina Vasilopoulou; Lefteris Lykouras

Evidence suggests that hippocampal volumetric abnormalities are present in first-episode schizophrenia. The hippocampus contains the highest brain levels of neurotrophic factors, which are major determinants of neuronal plasticity. Brain-derived neurotrophic factor (BDNF) influences neuronal survival, differentiation, synaptogenesis, and maintenance and is also correlated with neuronal activation in the hippocampus. BDNF is also involved in the development and modulation of dopaminergic-related systems. Alterations of serum BDNF levels have been shown in a number of studies with first episode patients with schizophrenia, probably reflecting an association between BDNF and the pathogenesis of the disorder. In the present study we investigated the correlation between serum BDNF levels and hippocampal volumes in a sample of first episode drug-naïve patients with schizophrenia (FEP) and healthy control subjects. We found that hippocampal volume (HV) was decreased in FEP patients. Corrected right HV of FEP patients were significantly smaller compared to corrected right HVs of healthy subjects. The serum BDNF levels in the sample of FEP patients was significantly reduced compared to the healthy subjects. A significant positive association was found between serum BDNF and the corrected right HV in the group of patients such that the smaller the HV, the more reduced the serum BDNF levels. (Pearson r=0.452, p=0.045). Our findings indicate that low serum BDNF levels are associated with reduction in HV at the onset of schizophrenia and may further support the theory of a neuroprogressive-neurotoxic reaction associated with the onset of psychosis.


Neuropsychobiology | 2010

Association of Serum Brain-Derived Neurotrophic Factor and Duration of Untreated Psychosis in First-Episode Patients with Schizophrenia

Emmanouil Rizos; Panagiota Michalopoulou; N. Siafakas; N. Stefanis; A. Douzenis; Ioannis Rontos; Efstathios Laskos; A. Kastania; V. Zoumpourlis; Lefteris Lykouras

Background/Aims: The brain-derived neurotrophic factor (BDNF) levels in serum and the central nervous system are altered in patients with schizophrenia, suggesting that changes in the expression of BDNF might contribute to the disease pathophysiology. Long duration of untreated psychosis (DUP) has been associated with poorer prognosis in patients with schizophrenia. Such a relationship of untreated psychosis to outcome may indicate a neurodegenerative process and may have important implications for understanding the pathophysiology of schizophrenia. Methods: In this study, we investigated the association between serum BDNF levels and DUP in a sample of drug-naïve patients in their first episode of schizophrenia (FEP). We investigated serum BDNF levels in a sample of 37 drug-naïve FEP patients and 21 matched healthy subjects. Results: The serum BDNF level in the sample of FEP was significantly reduced compared to the healthy subjects (18.87 ± 8.23 vs. 29.2 ± 7.73 ng/ml, t = 4.76, d.f. = 57, p = 0.01). A negative correlation was found between serum BDNF levels and DUP in the group of patients (r = –0.346, p = 0.036). Conclusions: Our findings indicate that low serum BDNF levels at the onset of schizophrenia were associated with a long DUP and this could reflect an acute neurodegenerative reaction during the untreated phase of psychosis.


Journal of Affective Disorders | 2013

A magnetic resonance imaging study of hippocampal, amygdala and subgenual prefrontal cortex volumes in major depression subtypes: Melancholic versus psychotic depression

Konstantina Vassilopoulou; Matilda Papathanasiou; Ioannis Michopoulos; Fotini Boufidou; Panagiotis Oulis; Nikolaos Kelekis; Emmanouil Rizos; Chrysoula Nikolaou; Christos Pantelis; Dennis Velakoulis; Lefteris Lykouras

BACKGROUND Volumetric studies examining brain structure in depression subtypes are limited and inconclusive. The aim of the current study was to compare the volumes of brain regions previously implicated in depression among patients with melancholic major depressive disorder (MDD), patients with psychotic MDD and normal controls. METHODS Twenty two patients with melancholic MDD, 17 with psychotic MDD and 18 normal controls were included in the study. Hippocampal (HV), amygdala (AV), anterior (ASCV) and posterior (PSCV) subgenual cortex volumes were measured on magnetic resonance volumetric images. RESULTS There were no volumetric differences between patients with melancholic and psychotic subgroups. We identified larger AVs and smaller left ASCVs in both patient groups compared to controls with medium to large effect sizes. Regression analysis revealed that AVs were predicted by the presence of depression, late depression-onset, insomnia and left hippocampal tail volume in patients, but not in controls. There were no differences in HVs, right ASCVs and PSCVs across the 3 groups. LIMITATIONS Small sample size, a possible inclusion of paracingulate gyrus in ASCV and PSCV tracings, significant differences in education level and medication status are discussed as limitations. CONCLUSIONS Diagnostically delineated melancholic and psychotic MDD patients do not differ in medial temporal and cingulate volumes. However, significant volumetric differences were detected between both patient-groups and controls.


PLOS ONE | 2014

A Longitudinal Study of Alterations of Hippocampal Volumes and Serum BDNF Levels in Association to Atypical Antipsychotics in a Sample of First-Episode Patients with Schizophrenia

Emmanouil Rizos; Matilda Papathanasiou; Panagiota Michalopoulou; Efstathios Laskos; Aggeliki Mazioti; Anastasia N. Kastania; Konstantina Vasilopoulou; Paraskevi Nikolaidou; Dimitrios Margaritis; Charalabos Papageorgiou; Ioannis Liappas

Background Schizophrenia is associated with structural and functional abnormalities of the hippocampus, which have been suggested to play an important role in the formation and emergence of schizophrenia syndrome. Patients with schizophrenia exhibit significant bilateral hippocampal volume reduction and progressive hippocampal volume decrease in first-episode patients with schizophrenia has been shown in many neuroimaging studies. Dysfunction of the neurotrophic system has been implicated in the pathophysiology of schizophrenia. The initiation of antipsychotic medication alters the levels of serum Brain Derived Neurotrophic Factor (BDNF) levels. However it is unclear whether treatment with antipsychotics is associated with alterations of hippocampal volume and BDNF levels. Methods In the present longitudinal study we investigated the association between serum BDNF levels and hippocampal volumes in a sample of fourteen first-episode drug-naïve patients with schizophrenia (FEP). MRI scans, BDNF and clinical measurements were performed twice: at baseline before the initiation of antipsychotic treatment and 8 months later, while the patients were receiving monotherapy with second generation antipsychotics (SGAs). Results We found that left hippocampal volume was decreased (corrected left HV [t = 2.977, df = 13, p = .011] at follow-up; We also found that the higher the BDNF levels change the higher were the differences of corrected left hippocampus after 8 months of treatment with atypical antipsychotics (Pearson r = 0.597, p = 0.024). Conclusions The association of BDNF with hippocampal volume alterations in schizophrenia merits further investigation and replication in larger longitudinal studies.


World Journal of Biological Psychiatry | 2009

Tardive dyskinesia in a patient treated with quetiapine

Emmanouil Rizos; A. Douzenis; Rossetos Gournellis; Christos Christodoulou; Lefteris Lykouras

Quetiapine is an atypical antipsychotic that is believed to have a low D2 binding affinity in striatal and extrastriatal regions. We report the case of a female patient with the diagnosis of schizoaffective disorder (using DSM-IV-TR criteria) who initially received amisulpride for 3 months, discontinued gradually because of persistent and distressing extra-pyramidal symptoms, and who developed tardive dyskinesia 3 months later after the initiation of quetiapine. A trial with ziprasidone resulted in a further worsening of tardive dyskinesia symptoms. A further trial with aripiprazole, improved her tardive dyskinesia symptoms. Although, it is under consideration the possibility that the improvement could have been due to the discontinuation of quetiapine, we conclude that aripiprazole improved the TD symptoms.


Psychiatric Genetics | 2009

Association of the dopamine D3 receptor Ser9Gly and of the serotonin 2C receptor gene polymorphisms with tardive dyskinesia in Greeks with chronic schizophrenic disorder.

Emmanouil Rizos; Nikolaos Siafakas; Eleni Katsantoni; Vassiliki Lazou; Konstantinos Sakellaropoulos; Anastasia N. Kastania; Sophia Kossida; Kalliopi-Stavroula Chatzigeorgiou; Georgios Arsenis; Loukia Zerva; Konstantinos Katsafouros; Lefteris Lykouras

Association of the dopamine D3 receptor Ser9Gly and of the serotonin 2C receptor gene polymorphisms with tardive dyskinesia in Greeks with chronic schizophrenic disorder Emmanouil N. Rizos, Nikolaos Siafakas, Eleni Katsantoni, Vassiliki Lazou, Konstantinos Sakellaropoulos, Anastasia Kastania, Sophia Kossida, Kalliopi-Stavroula Chatzigeorgiou, Georgios Arsenis, Loukia Zerva, Konstantinos Katsafouros and Lefteris Lykouras


Clinical Chemistry and Laboratory Medicine | 2014

Peripheral blood lymphocytes from patients with bipolar disorder demonstrate apoptosis and differential regulation of advanced glycation end products and S100B

Paraskevi Moutsatsou; James N. Tsoporis; Vasileios Salpeas; Ekaterini Bei; Basel Alevizos; Chrysoula Anagnostara; Shehla Izhar; Gerald Proteau; Emmanouil Rizos; Erifili Hatziagelaki; Ioannis K. Toumpoulis; Ioannis Rizos; Thomas G. Parker

Abstract Background: This study addresses the expression of the glycosylated proteins known as advanced glycation end products (AGEs), the calcium binding protein S100B and the apoptotic parameters cytochome c and caspase-3 activity in peripheral lymphocyte cytosolic extracts from a sample of bipolar disorder (BD) patients and healthy (control) subjects. Methods: Cross-sectional study of 35 patients with a clinical diagnosis of bipolar disease (10 euthymic, 12 depressed, 13 manic) and 10 healthy control subjects. Lymphocytes were used as a surrogate model in BD diagnosis and treatment. AGEs and S100B in lymphocyte cell extracts were measured by commercially available enzyme-linked immunosorbent assay. Results: AGEs were lower in all BD patients compared to healthy subjects. Depressed patients had approximately two-fold higher S100B levels compared to healthy subjects. Manic and depressed BD patients had increased superoxide dismutase mRNA levels. Apoptosis as measured by BAX/Bcl2 ratio, cytochrome c release, caspase-3 activity was increased in manic and depressed patients compared to healthy subjects. In the depressed patients, S100B levels correlated with cytochrome c release. Conclusions: In conclusion, our study shows decreased AGEs and increased S100B levels and caspase down-stream apoptosis in peripheral lymphocytes of BD patients that may underlie disease etiopathogenesis.


BMC Psychiatry | 2010

Porencephaly and psychosis: a case report and review of the literature

A. Douzenis; Emmanouil Rizos; Athanasia Papadopoulou; Matilda Papathanasiou; Lefteris Lykouras

BackgroundMalformations of the cerebral cortex are often associated with developmental delay and psychoses. Porencephaly is a rare congenital disorder of central nervous system involving a cyst or a cavity filled with cerebrospinal fluid, in brains parenchyma.Case presentationWe present a 25 years old woman with her first psychotic episode. She also suffers from porencephaly in the frontotemporal lobes region. It is emphasized that the two consistently abnormal brain regions in schizophrenia research had significant damage in this patient since birth. There is a total of only five cases of schizencephaly or porencephaly associated with psychosis in the scientific literature. Their clinical characteristics as well as the imaging results are described.ConclusionIt is unclear if porencephaly and psychosis concur by chance or are causally related. The area where the porencephalic cysts appear seems to be of relevance. This case highlights the need for further research.

Collaboration


Dive into the Emmanouil Rizos's collaboration.

Top Co-Authors

Avatar

Lefteris Lykouras

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

A. Douzenis

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Nikolaos Siafakas

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Sofia Chatziioannou

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Charalabos Papageorgiou

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Ioannis Michopoulos

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Anastasia N. Kastania

Athens University of Economics and Business

View shared research outputs
Top Co-Authors

Avatar

Rossetos Gournellis

National and Kapodistrian University of Athens

View shared research outputs
Top Co-Authors

Avatar

Christos Christodoulou

National and Kapodistrian University of Athens

View shared research outputs
Researchain Logo
Decentralizing Knowledge