Analysis of factors related to cognitive impairment in a community-based, complete enumeration survey in Japan: the Nakayama study.

BACKGROUND: The number of patients with cognitive disorders is rapidly increasing in the world, becoming not only a medical problem, but also a social problem. There have been many reports that various factors are associated with cognitive dysfunction, but the factors have not yet been fully identified. This was a community-based complete enumeration study which aimed to identify risk and protective factors for dementia. METHODS: The first phase included all residents aged 65 years or older in a town in Japan. They completed many examinations, such as living conditions questionnaires, physical examination, Mini-Mental State Examination, and brain magnetic resonance imaging. The participants with suspected cognitive impairment underwent additional examinations for detailed evaluation in the second phase. Statistical analysis was performed to identify risk and protective factors for dementia after all participants were diagnosed. RESULTS: There were 927 participants in the baseline evaluation; 611 (65.9%) were healthy, 165 (17.8%) had mild cognitive impairment (MCI), and 151 (16.3%) had dementia. The age-standardised prevalence of dementia was 9.5%. Statistical analyses for amnestic MCI and Alzheimer's disease showed that risk factors for cognitive decline were diabetes mellitus, low activities of daily living, and living alone, and that protective factors were history of exercise and drinking habit. CONCLUSION: The present findings suggest that several lifestyle-related diseases and factors are associated with cognitive decline. These results support similar findings from previous studies and will be helpful for preventing dementia in the future.

DRD2 methylation to differentiate dementia with Lewy bodies from Parkinson's disease.

OBJECTIVE: The aim was to clarify whether DRD2 methylation changes in leukocytes of dementia with Lewy bodies (DLB) or Parkinson's disease (PD) patients are seen and can be used to discriminate between them. METHODS: Methylation rates were examined in 23 DLB subjects and 23 age- and sex-matched healthy controls and 37 PD patients and 37 age- and sex-matched healthy controls. RESULTS: Significant DRD2 DNA methylation changes were found in leukocytes of DLB and PD patients compared with healthy subjects. Discriminant analysis between DLB and PD using seven CpG sites demonstrated sensitivity and specificity of 83.8% and 90.9%, respectively. None of the CpG sites were associated with sex, age, age of onset, disease duration, and any of the neuropsychological tests in DLB and PD patients. CONCLUSION: This is the first report showing that DRD2 DNA methylation rates in leukocytes were increased in DLB patients and decreased in PD patients. These results may be an important step in understanding epigenetic mechanisms underlying DLB and PD pathogenesis and providing a novel biomarker for discriminating between them.

Frontotemporal lobar degeneration due to P301L tau mutation showing apathy and severe frontal atrophy but lacking other behavioral changes: A case report and literature review.

The clinical features in cases that have mutations in the microtubule-associated protein tau gene but lack prominent behavioral changes remain unclear. Here, we describe detailed clinical and pathological features of a case carrying the P301L tau mutation that showed only apathy until the middle stage of the course. The mother of this case was suspected to have mild cognitive decline at age 46. However, before she was fully examined, she had a subarachnoid hemorrhage at age 49 and died at age 53. An autopsy was not done. The proband of this pedigree, a 60-year-old right-handed Japanese man at the time of death, began to make mistakes at work at the age of 51 years. Until age 54, he showed only mild apathy with bradykinesia. Insight was well spared. Parkinsonism and echolalia developed at age 55, and pyramidal signs and oral tendency at age 57. Personality change, disinhibition, stereotypy, or semantic memory impairment was not found throughout the course. The final neurological diagnosis was unspecified dementia. Pathological examination demonstrated numerous round four-repeat tau-positive three-repeat tau-negative or perinuclear ring-like neuronal cytoplasmic inclusions with many ballooned neurons in the frontal and temporal cortices and hippocampus. Genetic analysis using frozen brain tissue demonstrated a P301L tau mutation. Among 31 previously reported cases bearing the P301L tau mutation for which the data regarding initial symptoms are available, one clinical case showed only apathy with depression in the early stage. Given these findings, clinicians should be aware that a clinical course characterized only by apathy for several years, which can be misdiagnosed as a psychiatric disorder, is one of the clinical presentations associated with P301L tau mutation.

MEF2C mRNA expression and cognitive function in Japanese patients with Alzheimer's disease.

AIM: Despite continuing research into Alzheimer's disease (AD), its pathological mechanisms and modulating factors remain unknown. Several genes influence AD pathogenesis by affecting inflammatory pathways. Myocyte-enhancer factor 2C (MEF2C) is one such candidate gene for AD. METHODS: We examined MEF2C mRNA expression levels and methylation rates of CpG on its promoter region in peripheral leukocytes from Japanese AD patients compared with age- and sex-matched control subjects. RESULTS: In peripheral leukocytes, MEF2C mRNA expression levels in AD subjects were significantly lower than those in control subjects (0.86 ± 0.25 vs 0.99 ± 0.27, respectively, P = 0.007) and were correlated with the Alzheimer's Disease Assessment Scale (r = -0.345, P = 0.049) and the Mini Mental State Examination (r = 0.324, P = 0.02). No significant differences were found in methylation rates between AD and control subjects. CONCLUSION: MEF2C mRNA expression in leukocytes may be a biological marker for cognitive decline in AD.

Pick's disease with neuronal four-repeat tau accumulation in the basal ganglia, brain stem nuclei and cerebellum.

It is very rare that cases of Pick's disease, a representative three-repeat (3R) tauopathy, also have significant four-repeat (4R) tau accumulation. Here, we report a Pick's disease case that clinically showed behavioral variant frontotemporal dementia without motor disturbance during the course, and pathologically had 3R tau-positive Pick bodies as well as numerous 4R tau-positive neuronal cytoplasmic inclusions (NCIs). Abundant 3R tau-positive 4R tau-negative spherical or horseshoe-shaped Pick bodies were found in the frontotemporal cortex, limbic region, striatum and pontine nucleus. On the other hand, many 4R tau-positive, 3R tau-negative, Gallyas-negative dot-, rod- or intertwined skein-like NCIs were found mainly in the subthalamic nucleus, pontine nucleus, inferior olivary nucleus and cerebellar dentate nucleus. Tufted astrocytes, astrocytic plaques, argyrophilic grains or globular glial inclusions were absent. Double-labeling immunofluorescence demonstrated that 3R tau was hardly accumulated in 4R tau-positive inclusions. On tau immunoblotting, while 60 and 64 kDa bands were demonstrated in the frontal cortex, 60, 64 and 68 kDa bands, as well as the 33 kDa tau fragments that are reported to be characteristic of progressive supranuclear palsy brains, were found in the basal ganglia and cerebellum. No mutation was identified in the tau gene. The present case suggests that, although probably rare, some Pick's disease cases have non-negligible 4R tau pathology in the subcortical nuclei, and that such 4R tau pathology can affect the evaluation of the distribution of AT8-positive tau pathology in Pick's disease cases.

DNA methylation changes at SNCA intron 1 in patients with dementia with Lewy bodies.

AIM: It is difficult to diagnose dementia with Lewy bodies (DLB) because it exhibits clinical and neuropathological overlap with both Alzheimer's disease and Parkinson's disease. The α-synuclein protein is a major component of Lewy bodies, and accumulation of α-synuclein aggregates causes synaptic dysfunction in DLB. Epigenetic changes at the synuclein alpha ( SNCA ) gene may be involved in DLB pathogenesis. METHODS: We examined DNA methylation rates at 10 CpG sites located in intron 1 of SNCA and SNCA mRNA expression in peripheral leukocytes to compare DLB patients (n = 20; nine men, 11 women; age = 78.8 ± 7.7 years) with healthy controls (n = 20; eight men, 12 women; age = 77.0 ± 6.9 years). RESULTS: The methylation rate at CpG 4 ( P = 0.002) and the overall mean methylation rate at these sites (P < 0.001) were significantly lower in DLB patients than in healthy controls after Bonferroni correction. Although SNCA126 , a partial form of SNCA mRNA expression, was significantly increased in DLB ( P = 0.017), there was no significant difference in total SNCA mRNA expression between DLB patients and healthy controls ( P = 0.165). No correlation was observed between SCNA mRNA expression levels and blood DNA methylation rates in either DLB or healthy controls. CONCLUSION: Our findings indicated that lower methylation rates may be a biomarker for DLB.

Elevated TREM2 mRNA expression in leukocytes in schizophrenia but not major depressive disorder.

The pathological mechanisms of schizophrenia (SCZ) have not been clarified, but the microglia hypothesis has recently been discussed. We previously reported that the mRNA for a protein related to activation of microglia, triggering receptor expressed on myeloid cell 2 (TREM2), is expressed higher in peripheral leukocytes in SCZ than controls. In this study, we analyzed TREM2 mRNA expression in leukocytes from both SCZ and major depressive disorder (MDD) patients. We compared 50 SCZ patients and 42 MDD patients with age-matched controls. Levels of TREM2 mRNA in leukocytes were analyzed with quantitative real-time PCR method using TaqMan probe. TREM2 mRNA expression was significantly higher in leukocytes of SCZ subjects than controls, but the expression level was non-significantly different in MDD subjects. We observed a decrease in TREM2 mRNA expression in leukocytes from one SCZ patient after clozapine treatment. The expression did not change following ECT, but the expression level in this patient was still significantly higher than that in controls. We conclude that the high amount of TREM2 mRNA expression in leukocytes is specific to SCZ but not MDD and that changes in TREM2 mRNA expression may be a trait biomarker for SCZ.

Association Study and Meta-Analysis of Polymorphisms, Methylation Profiles, and Peripheral mRNA Expression of the Serotonin Transporter Gene in Patients with Alzheimer's Disease.

BACKGROUND/AIM: The aim of this study was to elucidate the relationship between Alzheimer's disease (AD) and the serotonin transporter gene (SLC6A4). METHODS: AD subjects (n = 43) and controls (n = 47) were recruited and evaluated. In leukocytes, we evaluated two polymorphisms in SLC6A4, the serotonin transporter length polymorphic region (5-HTT-LPR) and rs25531, as well as methylation rates of the SLC6A4 promoter region and the SLC6A4 mRNA expression level. We also performed a meta-analysis to examine the relationship between the frequency of the L allele and the risk of AD. RESULTS: The distributions of 5-HTT-LPR and rs25531 polymorphisms in AD subjects were not different from those of controls. Although the methylation rates in AD subjects were not significantly different from those of controls, the expression level in AD subjects was significantly higher than in controls. Additionally, the expression level in AD subjects was significantly correlated with apathy. Meta-analysis revealed that the L/L genotype significantly reduced the risk of AD, but only in the Caucasian population. CONCLUSION: Higher SLC6A4 mRNA expression in leukocytes in AD was associated with apathy regardless of SLC6A4 genotypes and methylation rates of the promoter region. The L/L genotype may reduce the risk of AD in the Caucasian population.

No abnormal hexanucleotide repeat expansion of C9ORF72 in Japanese schizophrenia patients.

Abnormal hexanucleotide repeat expansion of C9ORF72 is known to cause neurodegenerative disorders such as frontotemporal dementia. Additionally, patients with psychotic symptoms are more likely to have abnormal hexanucleotide repeat expansion than are patients without them. We investigated the hexanucleotide repeat sizes of C9ORF72 in 466 Japanese schizophrenia patients. We found no abnormal hexanucleotide repeat expansion. In conclusion, C9ORF72 may not be responsible for schizophrenia susceptibility in the Japanese population.

Relationship between regional cerebral blood flow and neuropsychiatric symptoms in dementia with Lewy bodies.

OBJECTIVE: This aim of this study was to examine the mechanisms underlying the neuropsychiatric symptoms in dementia with Lewy bodies by investigating regional cerebral blood flow. METHODS: Participants were 27 patients who fulfilled the diagnostic criteria for probable dementia with Lewy bodies. All subjects underwent single-photon emission computed tomography scans using technetium-99 m hexamethylpropyleneamine oxime. Neuropsychiatric symptoms were evaluated by neuropsychiatric inventory. Multiple regression analyses using neuropsychiatric inventory and voxel-based analyses of covariance of the regional cerebral blood flow images between subjects with or without each neuropsychiatric symptom were performed. Additionally, similar voxel-based analyses of covariance between subjects with each neuropsychiatric symptom and normal subjects were performed. RESULTS: There were no significant correlations in any psychiatric symptoms in multiple regression analyses. All subjects had hallucination but none had euphoria. We analyzed eight neuropsychiatric symptom scores with the exception of hallucination and euphoria using voxel-based analyses of covariance. Significant differences of regional cerebral blood flow were shown in groups with agitation, disinhibition, and irritability. Subjects with agitation showed hypoperfusion in the parietal lobule, the precuneus, and the angular gyrus, and hyperperfusion in the fusiform gyrus, the lingual gyrus, and the thalamus. Subjects with disinhibition showed hypoperfusion in the left frontal gyrus. Subjects with irritability showed hyperperfusion in the right frontal gyrus. There were no significant differences in regional cerebral blood flow between subjects with any neuropsychiatric symptoms and normal subjects. CONCLUSION: This study reveals that dysfunction of specific brain regions is associated with various neuropsychiatric symptoms in dementia with Lewy bodies.

Distribution of D-3-aminoisobutyrate-pyruvate aminotransferase in the rat brain.

BACKGROUND: D-3-aminoisobutyrate, an intermediary product of thymine, is converted to 2-methyl-3-oxopropanoate using pyruvate as an amino acceptor by D-3-aminoisobutyrate-pyruvate aminotransferase (D-AIB AT; EC 2.6.1.40). A large amount of D-AIB AT is distributed in the kidney and liver; however, small amounts are found in the brain. Recently, D-AIB AT was reported to metabolize asymmetric dimethylarginine (ADMA) in vivo and was suggested to be an important enzyme for nitric oxide metabolism because ADMA is a competitive inhibitor for nitric oxide synthase. In this study, we examined the distribution of D-AIB AT in the rat brain further to understand its role. We measured D-AIB AT mRNA and protein expression using quantitative RT-PCR and Western blotting, and monitored its distribution using immunohistochemical staining. RESULTS: D-AIB AT was distributed throughout the brain, with high expression in the cortex and hippocampus. Immunohistochemical staining revealed that D-AIB AT was highly expressed in the retrosplenial cortex and in hippocampal neurons. CONCLUSION: Our results suggest that D-AIB AT is distributed in the examined- just the regions and may play an important role there.

Aberrant Expression of GABA-Related Genes in the Hippocampus of 3xTg-AD Model Mice from the Early to End Stages of Alzheimer's Disease.

BACKGROUND: We explored the gene expression levels in the brain of 3xTg-AD model mice to elucidate the molecular pathological changes from the early to end stages of Alzheimer's disease (AD). OBJECTIVE: We re-analyzed our previously published microarray data obtained from the hippocampus of 3xTg-AD model mice at 12 and 52 weeks of age. METHODS: Functional annotation and network analyses of the up- and downregulated differentially expressed genes (DEGs) in mice aged 12 to 52 weeks were performed. Validation tests for gamma-aminobutyric acid (GABA)-related genes were also performed by quantitative polymerase chain reaction (qPCR). RESULTS: In total, 644 DEGs were upregulated and 624 DEGs were downregulated in the hippocampus of both the 12- and 52-week-old 3xTg-AD mice. In the functional analysis of the upregulated DEGs, 330 gene ontology biological process terms, including immune response, were found, and they interacted with each other in the network analysis. In the functional analysis of the downregulated DEGs, 90 biological process terms, including several terms related to membrane potential and synapse function, were found, and they also interacted with each other in the network analysis. In the qPCR validation test, significant downregulation was seen for Gabrg3 at the ages of 12 (p = 0.02) and 36 (p = 0.005) weeks, Gabbr1 at the age of 52 weeks (p = 0.001), and Gabrr2 at the age of 36 weeks (p = 0.02). CONCLUSION: Changes in immune response and GABAergic neurotransmission may occur in the brain of 3xTg mice from the early to end stages of AD.

Gestational exposure to haloperidol changes Cdkn1a and Apaf1 mRNA expressions in mouse hippocampus.

BACKGROUND: The onset of schizophrenia is associated with both genetic and environmental risks during brain development. Environmental factors during pregnancy can represent risk factors for schizophrenia, and we have previously reported that several microRNA and mRNA expression changes in fetal brains exposed to haloperidol during pregnancy may be related to the onset of this disease. This study aimed to replicate that research and focused on apoptotic-related gene expression changes. METHODS: Haloperidol (1 mg/kg) or aripiprazole (1 mg/kg) was injected into pregnant mice. Using RNA sequencing for the hippocampus of each offspring born from pregnant mice exposed to haloperidol, we analyzed genes identified as changed in our previous report and validated two apoptosis-related genes (Cdkn1a and Apaf1) using quantitative polymerase chain reaction (qPCR) methods. Furthermore, we attempted to elucidate the direct effects of haloperidol and aripiprazole on those mRNA expressions in in vitro experiments. RESULTS: RNA sequencing successfully replicated 16 up-regulated and 5 down-regulated genes in this study. Of those, up-regulations of Cdkn1a and Apaf1 mRNA expression were successfully validated by direct quantification. Moreover, haloperidol and aripiprazole dose-dependent upregulation of both mRNA expressions were confirmed in a Neuro2a cell line. CONCLUSIONS: In the hippocampus of offspring, intraperitoneal injection of haloperidol to pregnant mice induced up-regulation of apoptotic genes that representing the phenotypic change without apoptosis. These findings will be useful for understanding the molecular biological mechanisms underlying the effects of antipsychotics on the fetal brain.

Blood MAPT expression and methylation status in Alzheimer's disease.

Aim: This study aimed to investigate the expression levels and methylation status of microtubule-associated protein tau (MAPT) in the blood of Alzheimer's disease (AD) patients and age- and sex-matched healthy controls. Methods: Fifty AD outpatients and 50 healthy contorls were enrolled. Blood samples were collected for processing of complementary DNA and genomic DNA. MAPT messenger ribonucleic acid (mRNA) expression was analyzed by real-time quantitative polymerase chain reaction. The methylation rates of four cytosine-phosphate-guanine (CpG) sites in the upstream region of MAPT exon1 were evaluated by the pyrosequencing method. Results: No significant differences in MAPT mRNA expression levels were found between AD and control subjects (AD 0.97 ± 0.49 vs. control 1.0 ± 0.64, p = 0.62). MAPT mRNA expression levels were not correlated with any other clinical characteristics or results of psychological tests. MAPT mRNA expression levels were significantly higher in AD subjects treated with acetylcholinesterase inhibitors (AchEIs) (n = 25) than in subjects not treated with AChEIs (n = 25) (unmedicated 0.83 ± 0.33 vs. medicated 1.12 ± 0.59, p = 0.049). The AD subjects did not differ from the control subjects in methylation rates at selected CpG sites. MAPT methylation status were not correlated with clinical characteristics, the results of psychological tests, or MAPT mRNA expression. Conclusion: MAPT mRNA expression levels and methylation status in blood do not appear useful as biomarkers for AD or the examined CpG sites were not genetically significant for MAPT gene expression or AD pathology. However, AChEIs may alter MAPT mRNA expression. Further studies are needed to explore blood biomarkers that can discriminate AD patients from controls.

PICALM mRNA Expression in the Blood of Patients with Neurodegenerative Diseases and Geriatric Depression.

BACKGROUND: Phosphatidylinositol-binding clathrin assembly protein (PICALM) is a validated genetic risk factor for late-onset Alzheimer's disease (AD) and is associated with other neurodegenerative diseases. However, PICALM expression in the blood of neurodegenerative diseases remains elusive. OBJECTIVE: This study aimed to assess the usefulness of PICALM expression levels in the blood of patients with AD, Parkinson's disease (PD), dementia with Lewy bodies (DLB), and geriatric major depressive disorder (MDD) as a diagnostic biomarker. METHODS: In total, 45, 20, 21, and 19 patients with AD, PD, DLB, and geriatric MDD, respectively, and 54 healthy controls (HCs) were enrolled in the study. Expression data from Gene Expression Omnibus database (GSE97760), (GSE133347) and (GSE98793), (GSE48350), and (GSE144459) were used to validate the ability of biomarkers in the blood of patients with AD, PD, geriatric MDD, and a postmortem human AD brain and animal model of AD (3xTg-AD mouse), respectively. RESULTS: PICALM mRNA expression in human blood was significantly increased in patients with AD compared with that in HCs. PICALM mRNA expression and age were negatively correlated only in patients with AD. PICALM mRNA expression in human blood was significantly lower in patients with PD than in HCs. No changes in PICALM mRNA expression were found in patients with DLB and geriatric MDD. CONCLUSION: PICALM mRNA expression in blood was higher in patients with AD, but lower in patients with PD, which suggests that PICALM mRNA expression in human blood may be a useful biomarker for differentiating neurodegenerative diseases and geriatric MDD.

Blood CDKN2A Gene Expression in Aging and Neurodegenerative Diseases.

BACKGROUND: Cyclin-dependent kinase inhibitor 2A (CDKN2A) is an important gene in cellular senescence and aging. OBJECTIVE: This study assessed the utility of blood CDKN2A mRNA expression levels and methylation status as a potential biomarker for aging and the pathogenesis of Alzheimer's disease (AD). METHODS: The correlation between CDKN2A mRNA expression levels and age was examined in 45 healthy subjects, after which mRNA expression levels were compared among 46 AD patients, 20 mild cognitive impairment due to AD patients, 21 Parkinson's disease patients, 21 dementia with Lewy bodies patients, and 55 older healthy controls. The methylation rates of the second exon of the CDKN2A gene, known to influence its expression levels, was also examined. RESULTS: A significant correlation between CDKN2A mRNA expression levels and age was found (Spearman's rank correlation coefficient: r = 0.407, p = 0.005). CDKN2A mRNA expression levels in blood were significantly decreased in AD patients, although those of healthy controls were significantly increased with age. Further, only in AD patients were CDKN2A mRNA expression levels significantly and positively correlated with methylation rates. CONCLUSION: Although further research with a larger sample size is needed to elucidate the relationships between CDKN2A gene expression in blood and the development of other neurodegenerative diseases, CDKN2A mRNA expression in blood may be a biomarker for differentiating AD from normal aging and other neurodegenerative diseases.

Identifying Blood Transcriptome Biomarkers of Alzheimer's Disease Using Transgenic Mice.

The testing of pathological biomarkers of Alzheimer's disease (AD), such as amyloid beta and tau, is time-consuming, expensive, and invasive. Here, we used 3xTg-AD mice to identify and validate putative novel blood transcriptome biomarkers of AD that can potentially be identified in the blood of patients. mRNA was extracted from the blood and hippocampus of 3xTg-AD and control mice at different ages and used for microarray analysis. Network and functional analyses revealed that the differentially expressed genes between AD and control mice modulated the immune and neuroinflammation systems. Five novel gene transcripts (Cdkn2a, Apobec3, Magi2, Parp3, and Cass4) showed significant increases with age, and their expression in the blood was collated with that in the hippocampus only in AD mice. We further assessed previously identified candidate biomarker genes. The expression of Trem1 and Trem2 in both the blood and brain was significantly increased with age. Decreased Tomm40 and increased Pink1 mRNA levels were observed in the mouse blood. The changes in the expression of Snca and Apoe mRNA in the mouse blood and brain were similar to those found in human AD blood. Our results demonstrated that the immune and neuroinflammatory system is involved in the pathophysiologies of aging and AD and that the blood transcriptome might be useful as a biomarker of AD.

ABCA7 Gene Expression and Genetic Association Study in Schizophrenia.

INTRODUCTION: Although ATP-binding cassette sub-family A member 7 gene (ABCA7) is known to be associated with Alzheimer's disease, the relationship between ABCA7 and schizophrenia has been unknown. METHODS: Schizophrenia patients (n = 50; 24 males, 62.1 ± 0.50 years old) and age- and sex-matched healthy controls (n = 50) were recruited for the mRNA analysis. Additionally, a case-control study for the rs3764650 genotypes was performed with 1308 samples (control subjects; n = 527, schizophrenia patients; n = 781). All participants were Japanese, unrelated to each other, and living in the same area. RESULTS: The distributions of the rs3764650 genotypes in schizophrenia patients were not different from that of controls. However, the ABCA7 mRNA expression levels in schizophrenia patients were significantly higher than those in controls by a logistic regression analysis. Additionally, the ABCA7 mRNA expression levels in schizophrenia patients were correlated with the rs3764650 genotypes in a dose-dependent manner. DISCUSSION: The ABCA7 mRNA expression levels in peripheral blood with the rs3764650 genotypes may be related to pathological mechanisms in schizophrenia and may be a biological marker for schizophrenia.

CTLA4 mRNA expression in blood is lower in schizophrenia, but not in affective disorders.

CTL-associated antigen 4 (CTLA4) and its downstream signals compose an important mechanism that suppresses immune activity. Recent studies have shown that immune abnormalities are associated with the pathogenesis of schizophrenia (SCZ), but little research has been performed on the relevance of CTLA4 and SCZ. In the present study, we investigated the relationship between CTLA4 mRNA expression and SCZ. We examined the expression of CTLA4 mRNA in blood from patients with SCZ, bipolar disorder (BD), and major depressive disorder (MDD). We compared 50 SCZ subjects, 46 BD subjects, and 63 MDD subjects with age- and sex-matched healthy controls (HCs). Quantitative real-time PCR was performed to examine CTLA4 mRNA expression in peripheral blood using TaqMan probes. Levels of CTLA4 mRNA expression were significantly lower in patients with SCZ compared with HCs (p < 0.001), whereas no differences were found between affective disorder (BD and MDD) patients and HCs. We analyzed the correlation between CTLA4 mRNA expression and clinical parameters, but no significant correlation was found. The expression of CTLA4 mRNA was lower specifically in SCZ, suggesting that abnormal CTLA4 expression may be particularly related to the pathogenesis of SCZ. CTLA4 may be a useful diagnostic marker and a potential therapeutic target of SCZ.

Analysis of methylation and -141C Ins/Del polymorphisms of the dopamine receptor D2 gene in patients with schizophrenia.

The gene for dopamine receptor D2 (DRD2) is associated with schizophrenia (SCZ). Epigenetic changes may be related to SCZ pathology. The -141C Ins/Del polymorphism in DRD2 (rs1799732) is functional and associated with SCZ. Fifty SCZ patients and 50 control subjects were newly recruited and analyzed in addition to 50 previously reported SCZ samples and 50 previously reported control samples. Genomic DNA from peripheral leukocytes was analyzed. We replicated analysis of DNA methylation rates at seven CpG sites (CpG 1-1 to 1-7) and also analyzed five additional sites (CpG 2-1 to 2-5) in the upstream region of DRD2. We also performed genotyping of -141C IIns/Del and analyzed the effects of -141C Ins/Del on methylation of DRD2. Methylation rates were significantly lower in SCZ patients compared to control subjects, respectively. In control subjects, the methylation rates were significantly lower in individuals with the Ins/Ins genotype than in Del allele carriers. We replicated hypomethylation of the DRD2 promoter region in SCZ patients compared to age-matched control subjects. The -141C Ins/Del polymorphism affected the methylation rates in regions of DRD2. Hypomethylation and the -141C Ins/Del polymorphism of DRD2 may be biomarkers for SCZ.