1451
|
Watanabe Y, Someya T, Nawa H. Cytokine hypothesis of schizophrenia pathogenesis: evidence from human studies and animal models. Psychiatry Clin Neurosci 2010; 64:217-30. [PMID: 20602722 DOI: 10.1111/j.1440-1819.2010.02094.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The pathogenesis of schizophrenia has yet to be fully characterized. Gene-environment interactions have been found to play a crucial role in the vulnerability to this disease. Among various environmental factors, inflammatory immune processes have been most clearly implicated in the etiology and pathology of schizophrenia. Cytokines, regulators of immune/inflammatory reactions and brain development, emerge as part of a common pathway of genetic and environmental components of schizophrenia. Maternal infection, obstetric complications, neonatal hypoxia and brain injury all recruit cytokines to mediate inflammatory processes. Abnormal expression levels of specific cytokines such as epidermal growth factor, interleukins (IL) and neuregulin-1 are found both in the brain and peripheral blood of patients with schizophrenia. Accordingly, cytokines have been proposed to transmit peripheral immune/inflammatory signals to immature brain tissue through the developing blood-brain barrier, perturbing structural and phenotypic development of the brain. This cytokine hypothesis of schizophrenia is also supported by modeling experiments in animals. Animals treated with specific cytokines of epidermal growth factor, IL-1, IL-6, and neuregulin-1 as embryos or neonates exhibit schizophrenia-like behavioral abnormalities after puberty, some of which are ameliorated by treatment with antipsychotics. In this review, we discuss the neurobiological mechanisms underlying schizophrenia and novel antipsychotic candidates based on the cytokine hypothesis.
Collapse
Affiliation(s)
- Yuichiro Watanabe
- Department of Psychiatry, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
| | | | | |
Collapse
|
1452
|
Pelser D. Super size me: is a big Australia good for our health? Med J Aust 2010; 192:526-7. [PMID: 20438430 DOI: 10.5694/j.1326-5377.2010.tb03618.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 01/17/2010] [Indexed: 11/17/2022]
Abstract
Australia faces a federally instigated migration drive aimed at increasing its population to 35 million by 2049. Immigration is welcomed by politicians, economists and business people, who credit it with helping Australia fare better than other developed countries during the recent global financial crisis. Australia's capital cities will have to expand considerably to house the new migrants. Increased urbanisation, when not accompanied by appropriate town planning, is associated with higher rates of chronic disease. Despite the migration drive, Australia's population will continue to age, and by 2056 one in four Australians will be over the age of 65 years. Australian health services are already heavily burdened. Health professionals must engage with governments to ensure that appropriate plans are put in place to accommodate the increased burden of disease that will accompany a more populous Australia. Failure to do so will compromise the health of our nation.
Collapse
|
1453
|
Willeit M, Praschak-Rieder N. Imaging the effects of genetic polymorphisms on radioligand binding in the living human brain: A review on genetic neuroreceptor imaging of monoaminergic systems in psychiatry. Neuroimage 2010; 53:878-92. [PMID: 20399868 DOI: 10.1016/j.neuroimage.2010.04.030] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 04/08/2010] [Accepted: 04/12/2010] [Indexed: 12/16/2022] Open
Abstract
Imaging genetics is a research field that describes the impact of genetic risk variants on brain structure and function. While magnetic resonance based imaging techniques are able to provide complex information on a system level, positron emission tomography (PET) and single photon emission computer tomography (SPECT) allow for determination of distribution and density of single receptor molecules in the human brain. Major psychiatric disorders are highly heritable, and have been associated with a dysregulation in brain dopamine and serotonin systems. Understanding the role of genetic polymorphisms within these neurotransmitter systems on brain phenotype is essential. This review tries to cover the literature on the impact of gene variants implicated in psychiatric disorders on serotonin, dopamine, and MAO-A radioligand binding in living humans. The majority of PET and SPECT studies investigated the role of polymorphisms within genes coding for the serotonin and dopamine transporters, the serotonin 1A receptor, and the dopamine D2 receptor on G protein coupled receptors or transporter proteins critically involved in serotonin or dopamine neurotransmission. Other studies investigated the impact of variants in genes for monoamine oxidase-A (MAO-A) or brain derived neurotrophic factor on monoamine transporters, receptors, or MAO-A activity. Two main findings in healthy subjects emerge from the current literature: one is an increased binding of the selective ligand [(11)C]DASB to serotonin transporters in subjects homozygous for the triallelic 5-HTTLPR LA allele. The other one is decreased binding of the radioligand [(11)C]raclopride to dopamine D2 receptors in D2 Taq1 A1 allele carriers. Other findings reported are highly interesting but require independent replication.
Collapse
Affiliation(s)
- Matthäus Willeit
- Division of Biological Psychiatry, Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
| | | |
Collapse
|
1454
|
Radyushkin K, El-Kordi A, Boretius S, Castaneda S, Ronnenberg A, Reim K, Bickeböller H, Frahm J, Brose N, Ehrenreich H. Complexin2 null mutation requires a 'second hit' for induction of phenotypic changes relevant to schizophrenia. GENES BRAIN AND BEHAVIOR 2010; 9:592-602. [PMID: 20412316 DOI: 10.1111/j.1601-183x.2010.00590.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Schizophrenia is a devastating disease that affects approximately 1% of the population across cultures. Its neurobiological underpinnings are still unknown. Accordingly, animal models of schizophrenia often lack construct validity. As concordance rate in monozygotic twins amounts to only 50%, environmental risk factors (e.g. neurotrauma, drug abuse, psychotrauma) likely act as necessary 'second hit' to trigger/drive the disease process in a genetically predisposed individual. Valid animal models would have to consider this genetic-environmental interaction. Based on this concept, we designed an experimental approach for modeling a schizophrenia-like phenotype in mice. As dysfunction in synaptic transmission plays a key role in schizophrenia, and complexin2 (CPLX2) gene expression is reduced in hippocampus of schizophrenic patients, we developed a mouse model with Cplx2 null mutation as genetic risk factor and a mild parietal neurotrauma, applied during puberty, as environmental 'second hit'. Several months after lesion, Cplx2 null mutants showed reduced pre-pulse inhibition, deficit of spatial learning and loss of inhibition after MK-801 challenge. These abnormalities were largely absent in lesioned wild-type mice and non-lesioned Cplx2 null mutants. Forced alternation in T-maze, object recognition, social interaction and elevated plus maze tests were unaltered in all groups. The previously reported mild motor phenotype of Cplx2 null mutants was accentuated upon lesion. MRI volumetrical analysis showed a decrease of hippocampal volume exclusively in lesioned Cplx2 null mutants. These findings provide suggestive evidence for the 'second hit' hypothesis of schizophrenia and may offer new tools for the development of advanced treatment strategies.
Collapse
Affiliation(s)
- K Radyushkin
- Division of Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
1455
|
Deo AJ, Costa R, DeLisi LE, DeSalle R, Haghighi F. A novel analytical framework for dissecting the genetic architecture of behavioral symptoms in neuropsychiatric disorders. PLoS One 2010; 5:e9714. [PMID: 20300526 PMCID: PMC2838792 DOI: 10.1371/journal.pone.0009714] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 02/25/2010] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND For diagnosis of neuropsychiatric disorders, a categorical classification system is often utilized as a simple way for conceptualizing an often complex clinical picture. This approach provides an unsatisfactory model of mental illness, since in practice patients do not conform to these prototypical diagnostic categories. Family studies show notable familial co-aggregation between schizophrenia and bipolar illness and between schizoaffective disorders and both bipolar disorder and schizophrenia, revealing that mental illness does not conform to such categorical models and is likely to follow a continuum encompassing a spectrum of behavioral symptoms. RESULTS AND METHODOLOGY We introduce an analytic framework to dissect the phenotypic heterogeneity present in complex psychiatric disorders based on the conceptual paradigm of a continuum of psychosis. The approach identifies subgroups of behavioral symptoms that are likely to be phenotypically and genetically homogenous. We have evaluated this approach through analysis of simulated data with simulated behavioral traits and predisposing genetic factors. We also apply this approach to a psychiatric dataset of a genome scan for schizophrenia for which extensive behavioral information was collected for each individual patient and their families. With this approach, we identified significant evidence for linkage among depressed individuals with two distinct symptom profiles, that is individuals with sleep disturbance symptoms with linkage on chromosome 2q13 and also a mutually exclusive group of individuals with symptoms of concentration problems with linkage on chromosome 2q35. In addition we identified a subset of individuals with schizophrenia defined by language disturbances with linkage to chromosome 2p25.1 and a group of patients with a phenotype intermediate between those of schizophrenia and schizoaffective disorder with linkage to chromosome 2p21. CONCLUSIONS The findings presented are novel and demonstrate the efficacy of this approach in detection of genes underlying such complex human disorders as schizophrenia and depression.
Collapse
Affiliation(s)
- Anthony J. Deo
- Department of Biology, New York University, New York, New York, United States of America
- Center for Comparative Genomics and Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States of America
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Ramiro Costa
- Division of Molecular Imaging and Neuropathology, The New York State Psychiatric Institute, New York, New York, United States of America
| | - Lynn E. DeLisi
- Harvard Medical School, VA Boston Healthcare System, Brockton, Massachusetts, United States of America
| | - Rob DeSalle
- Center for Comparative Genomics and Department of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States of America
| | - Fatemeh Haghighi
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
- Division of Molecular Imaging and Neuropathology, The New York State Psychiatric Institute, New York, New York, United States of America
| |
Collapse
|
1456
|
Abstract
Schizophrenia is a complex genetic disorder manifesting combined environmental and genetic causation. Recently, genome-wide association experiments yielded remarkable new experimental evidence that is leading to a better understanding of the genetic models and the biological risk factors involved in schizophrenia. These studies have discovered uncommon copy number variations (mainly deletions) and common single nucleotide polymorphisms with alleles associated with schizophrenia. The aggregate data provide support for polygenic inheritance and for genetic overlap of schizophrenia with autism and with bipolar disorder. It is anticipated that the application of a myriad of tools from systems biology, in combination with biological functional experiments, will lead to a delineation of biological pathways involved in the pathophysiology of schizophrenia, and eventually to new therapies.
Collapse
Affiliation(s)
- Pablo V Gejman
- Department of Psychiatry and Behavioral Sciences; and Research Institute, Center for Psychiatric Genetics, NorthShore University HealthSystem Research Institute, Evanston, IL 60201, USA.
| | | | | |
Collapse
|
1457
|
Abstract
PURPOSE OF REVIEW Although most guidelines recommend monotherapy in schizophrenia, the combined application of multiple psychotropic agents is very common, especially in treatment-refractory cases. We review the empirical basis supporting these attempts and their relevance for clinical practice. RECENT FINDINGS Polypharmacy intends to address different aspects of treatment resistance, most importantly insufficient response of psychotic positive and negative symptoms, but also cognitive disturbances, affective comorbidity, obsessive-compulsive syndromes and side-effects of antipsychotic drugs. This review summarizes the current state of evidence of combined antipsychotic treatment strategies and the augmentation of antipsychotics with mood stabilizers, antidepressants and experimental substances. SUMMARY In general, rigorous data on combination therapy in schizophrenia are rare and further randomized controlled trials, naturalistic trials and head-to-head-trials are necessary. Some evidence supports a combination of antipsychotics and antidepressants for negative symptoms and comorbid major depressive episodes. The add-on of lithium and mood stabilizers lacks compelling evidence, but might be beneficial for specific subgroups. For treatment-resistant cognitive symptoms, antipsychotic medication should be combined with cognitive remediation, as no pharmacological add-on strategy has gained convincing evidence so far. Treatment-emergent positive and/or negative symptoms under clozapine monotherapy might benefit from adding a second atypical substance.
Collapse
|
1458
|
|
1459
|
Abstract
Recent genetic studies reinforce the view that current approaches to the diagnosis and classification of major psychiatric illness are inadequate. These findings challenge the distinction between schizophrenia and bipolar disorder, and suggest that more attention should be given to the relationship between the functional psychoses and neurodevelopmental disorders such as autism. We are entering a transitional period of several years during which psychiatry will need to move from using traditional descriptive diagnoses to clinical entities (categories and/or dimensions) that relate more closely to the underlying workings of the brain.
Collapse
Affiliation(s)
- Nick Craddock
- MRC Centre for Neuropsychiatric Genetics and Genomics, Henry Wellcome Building, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
| | | |
Collapse
|
1460
|
|
1461
|
Kaymaz N, van Os J. Murray et al. (2004) revisited: is bipolar disorder identical to schizophrenia without developmental impairment? Acta Psychiatr Scand 2009; 120:249-52. [PMID: 19744075 DOI: 10.1111/j.1600-0447.2009.01472.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
1462
|
Lisman JE, Coyle JT, Green RW, Javitt DC, Benes FM, Heckers S, Grace AA. Circuit-based framework for understanding neurotransmitter and risk gene interactions in schizophrenia. Trends Neurosci 2008; 16:e43-71. [PMID: 18395805 DOI: 10.1111/j.1755-5949.2010.00163.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many risk genes interact synergistically to produce schizophrenia and many neurotransmitter interactions have been implicated. We have developed a circuit-based framework for understanding gene and neurotransmitter interactions. NMDAR hypofunction has been implicated in schizophrenia because NMDAR antagonists reproduce symptoms of the disease. One action of antagonists is to reduce the excitation of fast-spiking interneurons, resulting in disinhibition of pyramidal cells. Overactive pyramidal cells, notably those in the hippocampus, can drive a hyperdopaminergic state that produces psychosis. Additional aspects of interneuron function can be understood in this framework, as follows. (i) In animal models, NMDAR antagonists reduce parvalbumin and GAD67, as found in schizophrenia. These changes produce further disinhibition and can be viewed as the aberrant response of a homeostatic system having a faulty activity sensor (the NMDAR). (ii) Disinhibition decreases the power of gamma oscillation and might thereby produce negative and cognitive symptoms. (iii) Nicotine enhances the output of interneurons, and might thereby contribute to its therapeutic effect in schizophrenia.
Collapse
Affiliation(s)
- John E Lisman
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
| | | | | | | | | | | | | |
Collapse
|