ATP and repetitive electric stimulation increases leukemia inhibitory factor expression in astrocytes: A potential role for astrocytes in the action mechanism of electroconvulsive therapy.

AIM: Electroconvulsive therapy (ECT) is effective for psychiatric disorders. However, its action mechanism remains unclear. We previously reported that transcription factor 7 (TCF7) was increased in patients successfully treated with ECT. TCF7 regulates Wnt pathway, which regulates adult hippocampal neurogenesis. Adult hippocampal neurogenesis is involved in the pathophysiology of psychiatric disorders. Astrocytes play a role in adult hippocampal neurogenesis via neurogenic factors. Of astrocyte-derived neurogenic factors, leukemia inhibitory factor (LIF) and fibroblast growth factor 2 (FGF2) activate Wnt pathway. In addition, adenosine triphosphate (ATP), released from excited neurons, activates astrocytes. Therefore, we hypothesized that ECT might increase LIF and/or FGF2 in astrocytes. To test this, we investigated the effects of ATP and electric stimulation (ES) on LIF and FGF2 expressions in astrocytes. METHODS: Astrocytes were derived from neonatal mouse forebrain and administered ATP and ES. The mRNA expression was estimated with quantitative reverse-transcription polymerase chain reaction. Protein concentration was measured with ELISA. RESULTS: ATP increased LIF, but not FGF2, expression. Multiple ES, but not single, increased LIF expression. Knockdown of P2X2 receptor (P2X2R) attenuated ATP-induced increase of LIF mRNA expression. In contrast, P2X3 and P2X4 receptors intensified it. CONCLUSION: P2X2R may mediate ATP-induced LIF expression in astrocytes and multiple ES directly increases LIF expression in astrocytes. Therefore, both ATP/P2X2R and multiple ES-induced increases of LIF expression in astrocytes might mediate the efficacy of ECT on psychiatric disorders. Elucidating detailed mechanisms of ATP/P2X2R and multiple ES-induced LIF expression is expected to result in the identification of new therapeutic targets for psychiatric disorders.

Cilostazol decreases duration of spreading depolarization and spreading ischemia after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Traditionally, angiographic vasospasm (aVS) has been thought to cause delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). However, successful treatment of aVS alone does not result in improved neurological outcome. Therefore, there may be other potential causes of poor neurological outcome, including spreading depolarization (SD). A recent study showed beneficial effects of cilostazol on DCI and neurological outcome. The present prospective clinical trial and experimental study focused on effects of cilostazol on SDs. METHODS: Fifty aSAH patients were treated with clip ligation and randomly assigned to a cilostazol (n = 23) or control group (n = 27). Effects of cilostazol on DCI, aVS, and SDs, measured with subdural electrodes, were examined. The effect of cilostazol on SD-induced perfusion deficits (spreading ischemia) was assessed in an aSAH-mimicking model. RESULTS: There was a trend for less DCI in the cilostazol group, but it did not reach our threshold for statistical significance (13.0% vs 40.0%, odds ratio = 0.266, 95% confidence interval [CI] = 0.059-1.192, p = 0.084). However, the total SD-induced depression duration per recording day (22.2 vs 30.2 minutes, ß = -251.905, 95% CI = -488.458 to -15.356, p = 0.043) and the occurrence of isoelectric SDs (0 vs 4 patients, ß = -0.916, 95% CI = -1.746 to -0.085, p = 0.037) were significantly lower in the cilostazol group. In rats, cilostazol significantly shortened SD-induced spreading ischemia compared to vehicle (Student t test, difference = 30.2, 95% CI = 5.3-55.1, p = 0.020). INTERPRETATION: Repair of the neurovascular response to SDs by cilostazol, as demonstrated in the aSAH-mimicking model, may be a promising therapy to control DCI. Ann Neurol 2018;84:873-885.

Clinical application of DEX/CRH test and multi-channel NIRS in patients with depression.

BACKGROUND: To reduce the number of patients with depression, biomarkers for clarifying psychiatric disorders are warranted. Numerous candidates have been proposed; however, near-infrared spectroscopy (NIRS) with multi-channel probes and a dexamethasone/corticotropin-releasing hormone (DEX/CRH) test are still surviving for practical demand. Thirty-one outpatients with depressed moods were analyzed using both biological tests. RESULTS: The non-suppressors, as indicated by the DEX/CRH test, exhibited a high severity on the Hamilton Depression Scale and severe anxiety on the State Trait Anxiety Scale. In addition, a unique response was identified via NIRS in the same group suggested by the DEX/CRH assessment. CONCLUSIONS: The results obtained from these biological tests did not fit well with the category defined by operative diagnostic criteria, such as the Diagnostic and Statistical Manual of Mental Disorders or The International Classification of Diseases. Thus, it is critical that the utility evaluations of candidate biomarkers not be assessed by comparisons with the categorized criteria for a specific psychiatric disorder. Trial registration UMIN000013214, Registered 21 February 2014.

Effects of Brain Temperature on Cerebrovascular Autoregulation During the Acute Stage of Severe Traumatic Brain Injury.

The pressure reactivity index (PRx) is calculated as a moving correlation coefficient between intracranial pressure (ICP) and mean arterial blood pressure (MABP), and this analytical value is viewed as reflecting a vasomotor response to MABP variability. At present, the factors influencing the PRx value during the acute stage of traumatic brain injury (TBI) are not known. We observed significant cases where changes in the calculated value of PRx seemed to be influenced by changes in brain temperature during the course of acute stage TBI. In one case, a patient was treated for 72 h with therapeutic brain hypothermia after a decompressive hemicraniectomy. During the hypothermic condition, the mean value of PRx was -0.019; however, after gradual rewarming, the value of PRx increased drastically, and the mean value during the rewarming period, when the brain temperature exceeded 35 °C, was 0.331. Similarly, in another case where the patient underwent therapeutic brain hypothermia, the PRx showed a mean value of -0.038 during the hypothermic condition, and a mean value of 0.052 during the rewarming period. In both cases, a trend toward a negative correlation between ICP and MABP during brain hypothermia shifted to a positive correlation upon rewarming.

Continuous Monitoring of Spreading Depolarization and Cerebrovascular Autoregulation after Aneurysmal Subarachnoid Hemorrhage.

Delayed cerebral ischemia (DCI) is a prominent complication after aneurysmal subarachnoid hemorrhage (aSAH). Although vasospasm of proximal cerebral arteries has been regarded as the main cause of DCI, vasospasm of distal arteries, microthrombosis, impaired autoregulation, cortical spreading depolarization (CSD), and spreading ischemia are thought to be involved in DCI after aSAH. Here, we describe a patient with aSAH in whom CSD and cerebrovascular autoregulation were evaluated using simultaneous electrocorticography and monitoring of the pressure reactivity index (PRx) after surgical clipping of a ruptured posterior communicating artery aneurysm. In this patient, a prolonged duration of CSD and elevation of PRx preceded delayed neurological deficit. Based on this observation, we propose a relationship between these factors and DCI. Assessment of cerebrovascular autoregulation may permit detection of the inverse hemodynamic response to cortical depolarization. Detection of DCI may be achieved through simultaneous monitoring of CSD and PRx in patients with aSAH.

Decreased Flow Velocity with Transcranial Color-Coded Duplex Sonography Correlates with Delayed Cerebral Ischemia due to Peripheral Vasospasm of the Middle Cerebral Artery.

BACKGROUND AND OBJECTIVE: Despite intensive therapy, vasospasm remains a major cause of delayed cerebral ischemia (DCI) in worsening patient outcome after aneurysmal subarachnoid hemorrhage (aSAH). Transcranial Doppler (TCD) and transcranial color-coded duplex sonography (TCCS) are noninvasive modalities that can be used to assess vasospasm. However, high flow velocity does not always reflect DCI. The purpose of this study was to investigate the utility of TCD/TCCS in decreasing permanent neurological deficits. METHODS: We retrospectively enrolled patients with aSAH who were treated within 72 hours after onset. TCCS was performed every day from days 4 to 14. Peak systolic velocity (PSV), mean velocity (MV), and pulsatility index were recorded and compared between DCI and non-DCI patients. In patients with DCI, endovascular therapy was administered to improve vasospasm, which led to a documented change in velocity. RESULTS: Of the 73 patients, 7 (9.6%) exhibited DCI. In 5 of the 7 patients, DCI was caused by vasospasm of M2 or the more peripheral middle cerebral artery (MCA), and the PSV and MV of the DCI group were lower than those of the non-DCI group after day 7. Intra-arterial vasodilator therapy (IAVT) was performed for all patients with DCI immediately to increase the flow volume by the next day. CONCLUSIONS: Increasing flow velocity cannot always reveal vasospasm excluding M1. In patients with vasospasm of M2 or more distal arteries, decreasing flow velocity might be suggestive of DCI. IAVT led to increases in the flow velocity through expansion of the peripheral MCA.

Importance of Early Postoperative Body Temperature Management for Treatment of Subarachnoid Hemorrhage.

BACKGROUND: The importance of acute-phase brain temperature management is widely accepted for prevention of exacerbation of brain damage by a high body temperature. METHODS: In this study, we investigated the influence of body temperature in the early postoperative period on the outcomes of 62 patients with subarachnoid hemorrhage who were admitted to our department. Body temperature was measured from day 4 to day 14 after onset. The patients were divided into those treated with surgical clipping (clip group) and coil embolization (coil group), those graded I-III (mild) and IV-V (severe) based on the Hunt & Hess classification on admission, those with and without development of delayed cerebral ischemia (DCI), and those with favorable and poor outcomes. Body temperatures throughout the hospital stay were compared in each group. RESULTS: There was no significant difference in body temperature between the clip and coil groups or between the mild and severe groups, but body temperature was significantly higher in patients with DCI compared to those without DCI, and in patients with a poor outcome compared to those with a favorable outcome. CONCLUSIONS: Fever in the early postoperative period of subarachnoid hemorrhage is associated with development of DCI and a poor outcome.

Strategies and Pitfalls of Motor-Evoked Potential Monitoring during Supratentorial Aneurysm Surgery.

BACKGROUND: The aims of this study were to reveal the strategies and pitfalls of motor-evoked potential (MEP) monitoring methods during supratentorial aneurysm surgery, and to discuss the drawbacks and advantages of each method by reviewing our experiences. METHODS: Intraoperative MEP monitoring was performed in 250 patients. Results from 4 monitoring techniques using combinations of 2 stimulation sites and 2 recording sites were analyzed retrospectively. RESULTS: MEP was recorded successfully in 243 patients (97.2%). Direct cortical stimulation (DCS)-spinal recorded MEP (sMEP) was used in 134 patients, DCS-muscle recorded MEP (mMEP) in 97, transcranial electrical stimulation (TES)-mMEP in 11 and TES-sMEP in 1. TES-mMEP during closure of the skull was used in 21 patients. DCS-mMEP was able to detect waveforms from upper and/or lower limb muscles. Alternatively, DCS-sMEP (direct [D]-wave) could accurately estimate amplitude changes. A novel "early warning sign" indicating ischemia was found in 21 patients, which started with a transiently increased amplitude of D-wave and then decreased after proximal interruption of major arteries. False-negative findings in MEP monitoring in 2 patients were caused by a blood insufficiency in the lenticulostriate artery and by a TES-sMEP recording, respectively. CONCLUSIONS: The results of this study suggest that to perform accurate MEP monitoring, DCS-mMEP or DCS-sMEP recording should be used as the situation demands, with combined use of TES-mMEP recording during closure of the skull. DCS-sMEP is recommended for accurate analysis of waveforms. We also propose a novel "early warning sign" of blood insufficiency in the D-wave.

Microarray Analysis of Human Blood During Electroconvulsive Therapy.

INTRODUCTION: Electroconvulsive therapy (ECT) is currently regarded as a significant treatment option for intractable psychiatric disorders, such as catatonic schizophrenia or treatment-resistant depression; however, the underlying molecular mechanism for its therapeutic effect remains obscure. METHODS: Employing microarray analysis (Human Genome U133 Plus 2.0 Array; Affymetrix, United States) of cDNA derived from the peripheral blood of patients with catatonic schizophrenia (n = 5), we detected a significant change in 145 genes (0.68%) before and after modified ECT (mECT). Moreover, we performed quantitative polymerase chain reaction validation of genes that had previously been suggested to be functionally related to schizophrenia. RESULTS: Of 4 genes examined (AKT3, TCF7, PPP3R1, and GADD45B), only TCF7 was increased during the mECT procedure (P = 0.0025). DISCUSSION: This study describes the first attempt to uncover the molecular mechanism of mECT using a microarray assay of mRNA derived from peripheral blood, and our results suggest that the TCF family may play a role in the functional mechanism of mECT.

Cranioplasty and Duraplasty with Transcranial Color-Coded Duplex Sonography after Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Transcranial color-coded duplex sonography (TCCS) is a noninvasive technique for monitoring of cerebral vasospasm after neurosurgery for aneurismal subarachnoid hemorrhage. In this surgery, surgical materials are used. The goal of the study was to identify materials that can be used with ultrasound and to propose methods for cranioplasty and duraplasty using materials that permit TCCS. METHODS: The chosen neurosurgical materials were titanium mesh plate (TMP), Gore-tex, SEAMDURA, gelatinous sponge, and oxidized cellulose. B-mode imaging was recorded with the materials placed between urethane resin 10 mm in diameter and the urethane phantom model. TCCS was performed to detect middle cerebral artery flow through TMP and Gore-tex. RESULTS: TMP and SEAMDURA permitted penetration of ultrasound in B-mode and Doppler imaging, but the other materials did not do so. CONCLUSIONS: A postcraniotomy window (PCW) on a line extending from the horizontal portion of M1 using only TMP permitted flow imaging with TCCS. In external decompression, TCCS was effective only without use of Gore-tex around the postcraniotomy window. This method allows the middle cerebral artery flow to be detected easily.

Relationship between Aging and Enlargement of Intracranial Aneurysms.

BACKGROUND: To predict possible enlargement of cerebral aneurysms with aging, we retrospectively analyzed aneurysm size in relation to patient age and aneurysm site. METHODS: We included 1332 unruptured and 2362 ruptured aneurysms detected in patients from the Yamaguchi Prefecture, Japan, from 1995 to 2005. RESULTS: Age-specific site distribution was not found in the unruptured aneurysms. In the ruptured aneurysms, the incidence of anterior communicating artery (AComA) aneurysms was higher than that of internal carotid posterior communicating (ICPC) artery aneurysms among the patients aged 40-49 years (32.6% versus 14.4%), whereas the difference was small among the elderly patients aged 70-79 years (25.8% versus 24.9%). In the AComA aneurysms, either in the unruptured or ruptured cases, no age-related change in size was found. In the ICPC aneurysms, either in the unruptured or in the ruptured cases, the size of the aneurysms 7 mm or larger increased with age. CONCLUSIONS: The sizes of AComA aneurysms may remain stable with aging. Therefore, the risk of rupture may be similar in young and elderly patients. Meanwhile, ICPC artery aneurysms may continue to grow throughout the patient's life, with an increasing risk of rupture.

Adverse events after unruptured cerebral aneurysm treatment: a single-center experience with clipping/coil embolization combined units.

BACKGROUND: Indications of clipping (Clip) or coil embolization (Coil) for unruptured cerebral aneurysms (uAN) was not elaborated because prediction of rupture and risk of treatment are difficult. This study aims to determine the risk-benefit analysis of treating uAN by a comprehensive and retrospective investigation of the adverse events and sequelae in patients treated by our Clip/Coil combined units. METHODS: Clip and Coil were performed in 141 and 80 patients, respectively; Clip for middle cerebral artery AN and Coil for paraclinoid or basilar apex AN. Worsening of modified Rankin scale or mini-mental state examination was defined as major morbidity. Minor morbidity or transient morbidity was defined as other neurologic deficits. Mortality and these morbidities were considered as serious adverse events. Convulsion or events outside the brain were defined as mild adverse events. RESULTS: Total mortality and major morbidity were low. Incidence of serious adverse events was not significantly different between the Clip and Coil (17 patients [12.1%] and 6 patients [7.5%]), but the number of total adverse events was significantly different (32 patients [22.7%] in Clip vs. 8 patients [10.0%] in Coil). Because mild morbidities were significantly more frequent in the Clip (20 patients [14.2%]) compared with the Coil (2 patients [2.5%]). Convulsion occurred in 11 (7.8%) patients in the Clip but none in the Coil. CONCLUSIONS: Our combined unit decreased the occurrence of mortality/major morbidity; however, minor adverse effects were common, especially in the Clip group because of many intrinsic problems of Clip itself. This result suggests further consideration for the treatment modality for uAN.

Postoperative dural arteriovenous fistula in a patient with Cowden disease: a case report.

We report the case of a 37-year-old male with Cowden disease that caused a gradual neurological deficit because of rupture of a brain stem cavernous hemangioma. Removal of the hemangioma and hematoma was performed with an infrafacial triangle approach. Nine months after the operation, magnetic resonance imaging showed abnormal vessels on the cerebellar surface. Digital subtraction angiography showed a dural arteriovenous fistula (dAVF) from part of the meningeal artery to the ectatic inferior vermian vein with cortical reflux. After embolization, surgical obliteration of the dAVF was performed. Surgical findings showed neovascularization in the thickened dura, in which dural vessels shunted to cerebellar vessels through adhesion between the dura mater and cerebellar surface. Therefore, the thickened dura was removed with the cerebellar surface. This case suggests that postoperative angiogenesis may cause arteriovenous fistula in patients with Cowden disease.

Fragmental or massive embolization in cardiogenic stroke caused by nonvalvular atrial fibrillation.

BACKGROUND: After cardioembolic stroke (CES), left atrial thrombus (LAT) is detected by transesophageal echocardiography (TEE) in some cases but not in others. We propose that there are 2 types of embolization in CES: fragmental and massive embolization. METHODS: Consecutive patients with nonvalvular atrial fibrillation (AF) of acute CES or transient ischemic attack (TIA) were prospectively enrolled in the study between May 2009 and July 2011. TEE was performed within 7 days of admission. The patients were classified into 2 groups: those with occlusion of the main trunk (internal carotid artery, M1, and basilar artery; group M) and those with occlusion of other distal arteries (group D). Clinical features were compared between patients who did and did not have a thrombus on TEE. RESULTS: Of the 41 patients in the study, 21 were in group M and 20 were in group D. Age, sex, and treatment with tissue plasminogen activator did not differ significantly between the 2 groups. The rate of detection of LAT was significantly higher in group D (14% v 65%; P < .001). CONCLUSIONS: Patients with distal artery occlusion had a significantly higher rate of LAT compared to those with main trunk occlusion. Distal artery occlusion in CES therefore tends to result from fragmental embolization and is associated with a remnant LAT, with which there may be a concern of a risk of early recurrence.

Correction: Ionic supramolecular polymerization of water-soluble porphyrins: balancing ionic attraction and steric repulsion to govern stacking.

[This corrects the article DOI: 10.1039/D2RA05542B.].

Multicenter prospective cohort study on volume management after subarachnoid hemorrhage: hemodynamic changes according to severity of subarachnoid hemorrhage and cerebral vasospasm.

BACKGROUND AND PURPOSE: Systemic circulation management has not been established for patients with poor grade aneurysmal subarachnoid hemorrhage (SAH) or delayed cerebral ischemia (DCI) after SAH. The aims of the study were to examine hemodynamic variables in these patients and to establish treatment strategies. METHODS: A multicenter prospective cohort study of hemodynamic variables from days 1 to 14 was performed using a transpulmonary thermodilution system (PiCCO Plus). Parameters were analyzed by Mann-Whitney test. Multivariate analysis was performed to identify parameters involved in onset of DCI. RESULTS: The subjects were 204 patients, including 138 with poor grade SAH (World Federation of Neurological Surgeons grades IV and V) and 52 who developed DCI. The extravascular lung water index, pulmonary vascular permeability index, and systemic vascular resistance index were significantly greater in patients with poor grade SAH compared with those with good grade SAH (World Federation of Neurological Surgeons I-III) on day 2 (P=0.049, P=0.039, and P=0.038). Cardiac index was significantly lower in patients with poor grade SAH on days 1 and 2 (P=0.027 and P=0.011). In patients with DCI, the global end-diastolic volume index was significantly lower than in those without DCI on days 3 to 5 (P=0.0053; P=0.048; and P=0.048). In multivariate analysis, median global end-diastolic volume index, cardiac index, and systemic vascular resistance index at an early stage of SAH (days 3-6) were independently related to onset of DCI (P=0.023, P=0.013, and P=0.003). CONCLUSIONS: Patients with poor grade SAH developed heart failure-like afterload mismatch at an early stage, and those with DCI had decreased global end-diastolic volume index (hypovolemia) in the early stage of SAH. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: UMIN000003794.

Seasonal variation in the incidence of aneurysmal subarachnoid hemorrhage associated with age and gender: 20-year results from the Yamaguchi cerebral aneurysm registry.

BACKGROUND: This study was a cerebral aneurysm registry study conducted in a region with few climatic differences. Based on data collected for over 20 years, seasonal variations and characteristics of subarachnoid hemorrhage (SAH) due to ruptured aneurysms were analyzed. METHODS: This study included 5,007 patients in the Yamaguchi Prefecture with aneurysmal SAH between 1986 and 2005. Incidence rates by month, sex, age, severity, and aneurysm site were analyzed. RESULTS: In women, seasonal variation was observed, in particular among those aged ≥50 years. Among those aged 50-69 years, the highest incidence was in October, and the nadir was in June (peak-to-trough ratio = 1.72). At age ≥70 years, this was slightly different, with the highest incidence in December and the nadir in July (peak-to-trough ratio = 1.48). However, there was no seasonal variation in men overall; it was limited to elderly men at age ≥70 years, with the highest incidence in January and the nadir in July (peak-to-trough ratio = 2.9). Aneurysm site and severity showed no relationship with seasonal variation. CONCLUSION: The present study shows seasonal variations in the onset of SAH. Seasonal variations in SAH differed depending on age and sex.

Genome-wide association study of atypical psychosis.

Atypical psychosis with a periodic course of exacerbation and features of major psychiatric disorders [schizophrenia (SZ) and bipolar disorder (BD)] has a long history in clinical psychiatry in Japan. Based upon the new criteria of atypical psychosis, a Genome-Wide Association Study (GWAS) was conducted to identify the risk gene or variants. The relationships between atypical psychosis, SZ and BD were then assessed using independent GWAS data. Forty-seven patients with solid criteria of atypical psychosis and 882 normal controls (NCs) were scanned using an Affymetrics 6.0 chip. GWAS SZ data (560 SZ cases and 548 NCs) and GWAS BD (107 cases with BD type 1 and 107 NCs) were compared using gene-based analysis. The most significant SNPs were detected around the CHN2/CPVL genes (rs245914, P = 1.6 × 10(-7)) , COL21A1 gene (rs12196860, P = 2.45 × 10(-7) ), and PYGL/TRIM9 genes (rs1959536, P = 7.73 × 10(-7) ), although none of the single-nucleotide polymorphisms exhibited genome-wide significance (P = 5 × 10(-8) ). One of the highest peaks was detected on the major histocompatibility complex region, where large SZ GWASs have previously disclosed an association. The gene-based analysis suggested significant enrichment between SZ and atypical psychosis (P = 0.01), but not BD. This study provides clues about the types of patient whose diagnosis lies between SZ and BD. Studies with larger samples are required to determine the causal variant.

Ionic supramolecular polymerization of water-soluble porphyrins: balancing ionic attraction and steric repulsion to govern stacking.

We have synthesized novel water-soluble anionic porphyrin monomers that undergo pH-regulated ionic supramolecular polymerization in aqueous media. By tuning the total charge of the monomer, we selectively produced two different supramolecular polymers: J- and H-stacked. The main driving force toward the J-aggregated supramolecular polymers was the ionic interactions between the sulfonate and protonated pyrrole groups, ultimately affording neutral supramolecular polymers. In these J-aggregated supramolecular polymers, amide groups were aligned regularly along polymer wedges, which further assembled in an edge-to-edge manner to afford nanosheets. In contrast, the H-aggregated supramolecular polymers remained anionic, with their amide NH moieties acting as anion receptors along the polymer chains, thereby minimizing repulsion. For both polymers, varying the steric bulk of the peripheral ethylene glycol (EG) units controlled the rates of self-assembly as well as the degrees of polymerization. This steric effect was further tunable, depending on the solvation state of the EG chains. Accordingly, this new family of supramolecular polymers was created by taking advantage of unique driving forces that depended on both the pH and solvent.

The genetic validation of heterogeneity in schizophrenia.

INTRODUCTION: Schizophrenia is a heritable disorder, however clear genetic architecture has not been detected. To overcome this state of uncertainty, the SZGene database has been established by including all published case-control genetic association studies appearing in peer-reviewed journals. In the current study, we aimed to determine if genetic variants strongly suggested by SZGene are associated with risk of schizophrenia in our case-control samples of Japanese ancestry. In addition, by employing the additive model for aggregating the effect of seven variants, we aimed to verify the genetic heterogeneity of schizophrenia diagnosed by an operative diagnostic manual, the DSM-IV. METHODS: Each positively suggested genetic polymorphism was ranked according to its p-value, then the seven top-ranked variants (p < 0.0005) were selected from DRD2, DRD4, GRIN2B, TPH1, MTHFR, and DTNBP1 (February, 2007). 407 Schizophrenia cases and 384 controls participated in this study. To aggregate the vulnerability of the disorder based on the participants' genetic information, we calculated the "risk-index" by adding the number of genetic risk factors. RESULTS: No statistically significant deviation between cases and controls was observed in the genetic risk-index derived from all seven variants on the top-ranked polymorphisms. In fact, the average risk-index score in the schizophrenia group (6.5+/-1.57) was slightly lower than among controls (6.6+/-1.39). CONCLUSION: The current work illustrates the difficulty in identifying universal and definitive risk-conferring polymorphisms for schizophrenia. Our employed number of samples was small, so we can not preclude the possibility that some or all of these variants are minor risk factors for schizophrenia in the Japanese population. It is also important to aggregate the updated positive variants in the SZGene database when the replication work is conducted.