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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We sought evidence for the involvement of mutations in the amyloid precursor protein gene (APP) in the pathogenesis of schizophrenia in two ways. First, linkage analysis was performed in a sample of 24 families multiply affected with schizophrenia. The genotypes were studied for GT12 (D21S210), a highly polymorphic microsatellite marker at the APP locus. Second, we used single strand conformation analysis (SSCA) to screen for mutations in exon 17 of APP in one affected member from each family and in a sample of 44 unrelated patients. In addition, we looked for linkage between schizophrenia and a series of highly polymorphic markers situated at approximately 20cM intervals along the long arm of chromosome 21. We were unable to find evidence for linkage to GT12 or the other markers studied. SSCA did not reveal any mutations in exon 17 of AP. We conclude that mutations within APP are an unlikely cause of schizophrenia. Moreover, this study provides no evidence for a major gene for schizophrenia on chromosome 21, and linkage can be excluded from much of this region under some genetic models.
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PMID:Failure to find linkage between schizophrenia and genetic markers on chromosome 21. 829 72

Genetic research may uncover the causes of severe mental disorders, and many projects have been undertaken to locate the genes responsible for schizophrenia, bipolar disorder, and Alzheimer disease. A number of sensitive legal and ethical issues have been raised, including 1) protection of confidential data concerning research subjects; 2) the assessment of types and degree of risk to subjects who participate in such studies; 3) the legal and ethical acceptability of substituted judgement on behalf of patients who may not be competent to provide informed consent; and 4) the separation of research and clinical roles in areas such as genetic counseling. Federal regulations and other guidelines are of limited value in dealing with such concerns, and many important human subjects issues will need to be dealt with by the investigator, subject to approval by a local Institutional Review Board. There does seem to be general agreement that informed consent must be obtained, potential risks of research need to be minimized, and confidentiality of sensitive data must be protected.
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PMID:Legal and ethical issues in psychiatric genetic research. 835 32

Defects in mitochondrial energy production have been implicated in several neurodegenerative disorders, such as Parkinson disease and amyotrophic lateral sclerosis. To study the contribution of mitochondrial defects to Alzheimer disease and schizophrenia, cytochrome-c oxidase (COX) activity and levels of the mtDNA4977 deletion in postmortem brain tissue specimens of patients were compared with those of asymptomatic age-matched controls. No difference in COX activity was observed between Alzheimer patients and controls in any of five brain regions investigated. In contrast, schizophrenic patients had a 63% reduction of the COX activity in the nucleus caudatus (P < 0.0001) and a 43% reduction in the cortex gyrus frontalis (P < 0.05) as compared to controls. The average levels of the mtDNA4977 deletion did not differ significantly between Alzheimer patients and controls, and the deletion followed similar modes of accumulation with age in the two groups. In contrast, no age-related accumulation of mtDNA deletions was found in schizophrenic patients. The reduction in COX activity in schizophrenic patients did not correlate with changes in the total amount of mtDNA or levels of the mtDNA4977 deletion. The lack of age-related accumulation of the mtDNA4977 deletion and reduction in COX activity suggest that a mitochondrial dysfunction may be involved in the pathogenesis of schizophrenia.
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PMID:Decreased cytochrome-c oxidase activity and lack of age-related accumulation of mitochondrial DNA deletions in the brains of schizophrenics. 853 74

This article describes the major techniques in molecular genetics, i.e., parametric and nonparametric linkage analyses, association studies and quantitative trait loci approaches. Some major molecular findings in schizophrenia, bipolar affective disorder and Alzheimer disease are presented. Aspects of the complexity of molecular genetic research in psychiatric disorders are discussed, including the relationship between genotype and phenotype, and between etiology and pathophysiology. Molecular findings in two genetic neuropsychiatric disorders, fragile X syndrome and Huntington's disease are described. These findings provoke some critical thoughts regarding future directions in psychiatric molecular research.
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PMID:The complexity of molecular genetic research in psychiatric disorders: advances and pitfalls. 940 81

We determined allele frequencies for polymorphisms at several loci of interest in neuropsychiatry-tryptophan hydroxylase (TPH), dopamine transporter protein (SLC6A3), D3 dopamine receptor (DRD3), apolipoprotein E (APOE), ciliary neurotrophic factor (CNTF), and the mu opioid receptor (OPRM1)-in samples of individuals from populations in several different parts of the world. Associations with psychiatric illness have been proposed for specific polymorphisms at TPH (suicide-related behaviors and impulsivity), DRD3 (schizophrenia and bipolar affective disorder), SLC6A3 (susceptibility to cocaine-induced paranoia and attention-deficit disorder), CNTF (psychosis), and OPRM1 (substance dependence). APOE alleles are related to risk of Alzheimer disease. We found significant allele frequency variation among populations at all six loci. These results will provide a global framework of normal variation at these loci that might have functional significance or otherwise be related to susceptibility to various disorders or behavioral phenomena. Knowledge of this variation can be important for study design and data interpretation when individuals from various population groups are research subjects and may eventually help lead to a better understanding of behavioral adaptation.
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PMID:Population studies of polymorphisms at loci of neuropsychiatric interest (tryptophan hydroxylase (TPH), dopamine transporter protein (SLC6A3), D3 dopamine receptor (DRD3), apolipoprotein E (APOE), mu opioid receptor (OPRM1), and ciliary neurotrophic factor (CNTF)). 979 Jul 47

Psychosis has been recognized as a common feature in neurodegenerative disease for many years. Hallucinations, delusions, and other psychotic phenomena occur in a wide range of degenerative disorders including Alzheimer disease, Huntington disease, Parkinson's disease, diffuse Lewy body disease, "Parkinson plus" syndromes, Pikc's disease, and other frontotemporal degenerations, amyotrophic lateral sclerosis, and prion associated diseases. It is also interesting that neurodegenerative disease-type dementia may be a feature in some psychotic illnesses such as schizophrenia. Clinical evaluation of psychosis in the setting of dementia presents a significant challenge for clinicians and researchers. Amnesia, language or speech impairments, and behavioral problems amy distort and obscure the presentation of symptoms. However, recognition and understanding of the psychotic manifestations may lead to the institution of more effective therapeutic or preventive options that can serve to delay long term care placement and improve patient and caregiver quality of life. In addition, a more comprehensive understanding of the pathophysiology, neuroanatomical substrates, and distinctive pathological features underlying the development of psychotic symptoms in neurodegenerative diseases may provide important insights into psychotic processes in general.
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PMID:Psychosis in Neurodegenerative Disease. 1032 Apr 31

Combined EEG and PET techniques show three activation levels of the cortex: deep sleep, relaxed state and alert. We propose, correspondingly, that a cortical module can be in one of three equivalent states: inactivated, pre-activated, and activated. Neuroimaging techniques can show activated cortical regions in detail. However, the functional connections (FCs) among them are not shown in the image. They can be found by EEG-coherence functions. This can be seen as a 'three-level- cortical graph'. A cortical graph is a mathematical representation where the cortical units (modules or regions) are represented by points (nodes) and the FCs are represented by lines between these points. At the upper level, activated modules can establish FCs implying high electrical coherence (they are the winners of a competitive process between preactivated modules at the middle level). We propose that, during alert state, the activated nodes and the dynamic switching among them always form connected graphs. It means that, for any possible configuration, there always exists a path (direct or indirect) between any couple of nodes. We base our view on (1) analysis of simple tasks by PET; (2) the existence of coordinated behavior in normal subjects; (3) cortical topologies previously proposed; and (4) computer simulations of cortico-cortical connections. We also suggest that disengaged (nonconnected) cortical graphs, produce 'functional disconnection syndromes' which cause some symptoms in schizophrenia, and Alzheimer disease.
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PMID:A topological hypothesis for the functional connections of the cortex. A principle of the cortical graphs' based on the neuroimaging. 1058 May 35

Schizophrenia and Alzheimer disease are both diseases of the brain that involve genetic susceptibility factors and for which the prevention or delay of symptom onset are important research goals. This paper provides some comparisons between current preventive efforts in schizophrenia and Alzheimer disease, focusing on certain ethical features of these endeavors such as potential discrimination, misdiagnosis, and stigma.
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PMID:Preventing schizophrenia and Alzheimer disease: comparative ethics. 1147 72

Impairments of glucose and mitochondrial function are important causes of brain dysfunction and therefore of brain disease. Abnormalities have been found in association with disease of the nervous system in most of the components of glucose/mitochondrial metabolism. In many, molecular genetic abnormalities have been defined. Brain glucose oxidation is abnormal in common diseases of the nervous system, including Alzheimer disease and other dementias, Parkinson disease, delirium, probably schizophrenia and other psychoses, and of course cerebrovascular disease. Defects in a single component and even a single mutation can be associated with different clinical phenotypes. The same clinical phenotype can result from different genotypes. The complex relationship between biological abnormality in brain glucose utilization and clinical disorder is similar to that in other disorders that have been intensively studied at the genetic level. Genes for components of the pathways of brain glucose oxidation are good candidate genes for disease of the brain. Preliminary data support the proposal that treatments to normalize abnormalities in brain glucose oxidation may benefit many patients with common brain diseases.
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PMID:Glucose/mitochondria in neurological conditions. 1242 Mar 64

Prepulse inhibition (PPI), a form of sensorimotor gating, occurs when an auditory startle response is markedly inhibited by a preceding sub-threshold stimulus (prepulse). Deficits in PPI have been demonstrated in patients with certain psychiatric disorders, such as schizophrenia, and in laboratory animals following specific pharmacological manipulations. Patients with Alzheimer's disease (AD) have not been tested in PPI, but have been shown to have abnormal sensory gating in another paradigm. Transgenic (Tg) CRND8 mice, which model Alzheimer's disease, carry the Swedish and Indiana familial Alzheimer's disease mutations of the human amyloid precursor protein gene and show age-related increases in beta-amyloid (Abeta) production, as well as plaque deposition. The present experiment investigated auditory startle threshold and PPI in TgCRND8 mice at various ages. In two longitudinal studies, PPI was examined in male TgCRND8 mice and non-transgenic (non-Tg) controls at 6-8 weeks of age (pre-plaque), and every 2 weeks thereafter until all mice were at least 16 weeks old (post-plaque). In a cross-sectional study, three different age sets of nai;ve TgCRND8 and non-Tg mice were tested: 10-12, 12-14, and 15-17 weeks old. In all three studies, TgCRND8 mice consistently and robustly demonstrated an enhanced response to a range of auditory startle stimuli compared to non-Tg mice. In addition, the TgCRND8 mice exhibited modest reductions in PPI, compared to non-Tg controls. These PPI deficits were present at pre- and post-plaque time points and did not appear to intensify with age; thus, they do not seem to correlate with the known neuropathology of TgCRND8 mice.
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PMID:Increased auditory startle response and reduced prepulse inhibition of startle in transgenic mice expressing a double mutant form of amyloid precursor protein. 1464 53


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