Publications by authors named "Shunsuke Sugiyama"

Article Synopsis
  • The 40-Hz auditory steady-state response (ASSR) is affected by factors like attention, stimulus type, duration, and inter-stimulus interval (ISI) in patients with schizophrenia.
  • In a meta-analysis of 33 studies, it was found that spectral power and phase-locking of the ASSR were lower in schizophrenia patients, with ISI playing a significant role in the differences observed compared to healthy controls.
  • A new hypothesis suggests that the ability to detect novelty based on stimulus duration and ISI is crucial in explaining why patients show less variation in their ASSR, indicating a need for further research to validate the 40-Hz ASSR as a schizophrenia biomarker.
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Social anxiety disorder (SAD) and panic disorder (PD) are prevalent anxiety disorders characterized by a complex interplay of genetic and environmental factors. Both disorders share overlapping features and often coexist, despite displaying distinct characteristics. Childhood life adversity, overall stressful life events, and genetic factors contribute to the development of these disorders.

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Major depressive disorder (MDD) is a clinically and genetically heterogeneous disorder. To reduce heterogeneity, large-scale genome-wide association studies have recently identified genome-wide significant loci associated with seven MDD subtypes. However, it was unclear in which tissues the genes near those loci are specifically expressed.

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Article Synopsis
  • - The study investigates how responses to auditory stimuli are influenced by prior stimuli using two measures: paired-pulse suppression (PPS) and prepulse inhibition (PPI), highlighting their roles in various diseases, particularly schizophrenia and Alzheimer's.
  • - Normative data were collected from healthy participants (35 females and 32 males, aged 19-70) to analyze the effects of age and sex on PPS and PPI values, with specific auditory stimuli tested via electroencephalography.
  • - Results indicated females exhibited stronger test responses but weaker inhibition across both measures; aging was associated with stronger responses and weaker inhibition in PPS, but not in PPI, suggesting that age and sex should be considered in future studies involving these auditory processing mechanisms
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Article Synopsis
  • Genetic factors, particularly Polygenic Risk Scores (PRSs), influence the likelihood of developing schizophrenia (SZ) and bipolar disorder (BD), with findings showing that SZ risk groups exhibit significant cognitive impairments.
  • Epigenome-wide association studies (EWASs) revealed numerous differentially methylated positions (DMPs) related to SZ in blood samples, highlighting a stark contrast between genetic SZ risk patients and those with lower genetic risks.
  • DNA Methylation Risk Scores (MRSs) for SZ were notably higher in SZ patients compared to healthy controls, especially among those with elevated genetic SZ risk, suggesting a potential epigenetic link to the disorder's pathogenesis.
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  • Adjustment disorder has three subtypes: with depressed mood, with anxiety, and with disturbance of conduct, and it shows moderate heritability.
  • There are strong genetic correlations between adjustment disorder and major depressive disorder (MDD), anxiety disorders, and risk-tolerant personality, suggesting they may share similar genetic risks.
  • While adjustment disorder is positively linked to an array of psychiatric conditions like schizophrenia and bipolar disorder, it shows no significant correlation with obsessive-compulsive disorder or Tourette syndrome, despite other related disorders exhibiting such correlations.
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  • The study investigates the role of mitochondrial genetic variants in the development of bipolar disorder (BD), schizophrenia (SZ), and psychotic disorders (PSY) in a Japanese population, highlighting that previous research primarily focused on individuals of European ancestry.
  • Using quality control methods, researchers analyzed 45 genetic variants in 420 participants (BD patients, SZ patients, and healthy controls) to identify associations with the disorders.
  • Four specific variants showed significant associations with BD and PSY, particularly the rs200044200 variant, which was found only in BD patients, suggesting mitochondrial dysfunction may play a role in the pathogenesis of these disorders.
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Objective: Olfactory impairments, including identification, have been reported in patients with schizophrenia, while few studies have examined the olfactory function of unaffected first-degree relatives of patients with schizophrenia, and the sample sizes of first-degree relatives were relatively small. Here, we investigated olfactory identification ability among patients with schizophrenia, first-degree relatives and healthy controls (HCs) using relatively large sample sizes at a single institute.

Methods: To assess olfactory identification ability, the open essence odorant identification test was administered to 172 schizophrenia patients, 75 first-degree relatives and 158 healthy controls.

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  • Patients with schizophrenia (SZ) show moderate reductions in brainstem volumes, particularly in structures like the pons, compared to healthy controls.
  • A study involving MRI scans of 156 SZ patients and 205 healthy individuals revealed significantly smaller pons volumes in male SZ patients, correlated with lower education levels.
  • The research suggests that the reduction in pons volume in these male patients may occur before or around the onset of schizophrenia, rather than being a result of the illness itself.
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Wind-up is a nociceptive-specific phenomenon in which pain sensations are facilitated, in a frequency-dependent manner, by the repeated application of noxious stimuli of constant intensity, with invariant tactile sensations. Thus, cortical activities during wind-up could be an alteration associated with pain potentiation. We aimed to investigate somatosensory-evoked cortical responses and induced brain oscillations during wind-up by recording magnetoencephalograms.

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The 40-Hz auditory steady-state response (ASSR) has received special attention as an index of gamma oscillations owing to its association with various neuropsychiatric disorders including schizophrenia. When a periodic stimulus is presented, oscillatory responses are often elicited not only at the stimulus frequency, but also at its harmonic frequencies. However, little is known about the effect of 40-Hz subharmonic stimuli on the activity of the 40-Hz ASSR.

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Prepulse inhibition (PPI) is sensory suppression whose mechanism (i.e., whether PPI originates from specific inhibitory mechanisms) remains unclear.

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Previous studies have suggested that change-related cortical responses are phenomena similar to the onset response and could be applied to the loudness dependence of auditory evoked potential (LDAEP) paradigm. In the present study, we examined the relationship between LDAEP and the change-related response using electroencephalography findings in 50 healthy subjects. There were five conditions (55, 65, 75, 85, and 95 dB) for LDAEP and five similar conditions (abrupt sound pressure increase from 70 to 75, 80, 85, 90, and 95 dB) for the change-related response.

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  • Reproductive behaviors, like the age of first sexual intercourse and age at first birth, show a connection to psychiatric disorders, particularly anxiety-related conditions, but the exact genetic links are not fully understood.
  • The study analyzed data from a large genome-wide association study (GWAS) involving thousands of participants to explore correlations between reproductive phenotypes and anxiety disorders.
  • Findings indicated that earlier ages for sexual intercourse and first births correlate with increased anxiety disorders, while those same behaviors have mixed effects on obsessive-compulsive disorder, highlighting complex genetic interactions.
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Wind-up like pain or temporal summation of pain is a phenomenon in which pain sensation is increased in a frequency-dependent manner by applying repeated noxious stimuli of uniform intensity. Temporal summation in humans has been studied by observing the increase in pain or flexion reflex by repetitive electrical or thermal stimulations. Nonetheless, because the measurement is accompanied by severe pain, a minimally invasive method is desirable.

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Schizophrenia and bipolar disorder display clinical similarities and dissimilarities. We investigated whether the genetic factor differentiating schizophrenia from bipolar disorder is genetically associated with cognitive phenotypes and hippocampal volumes. We revealed genetic overlaps of the genetic differentiating factor with low general cognitive ability, low childhood IQ, low educational attainment and reduced hippocampal volumes.

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Cigarette smoking is highly prevalent among patients with bipolar disorder (BD). Structural brain abnormalities related to smoking behavior and BD risk are indicated by magnetic resonance imaging (MRI) studies. However, cortical alterations common to smoking behavior and BD remain unclear.

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Paired pulse suppression is an electrophysiological method used to evaluate sensory suppression and often applied to patients with psychiatric disorders. However, it remains unclear whether the suppression comes from specific inhibitory mechanisms, refractoriness, or fatigue. In the present study, to investigate mechanisms of suppression induced by an auditory paired pulse paradigm in 19 healthy subjects, magnetoencephalography was employed.

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Blonanserin is a second-generation antipsychotic for the treatment of schizophrenia. Blonanserin has two different routes of administration: oral tablets/powder and transdermal patches. The aim of this study was to investigate as a post-hoc analysis of an original study whether switching from blonanserin tablets/powders to transdermal patches would reduce extrapyramidal symptoms (EPS) and/or the dose of antiparkinsonian drugs for the stabilization of blood pharmacokinetics in patients with schizophrenia.

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Gamma oscillations have received considerable attention owing to their association with cognitive function and various neuropsychiatric disorders. However, interactions of gamma oscillations at different frequency bands in humans remain unclear. In the present magnetoencephalographic study, brain oscillations in a wide frequency range were examined using a time-frequency analysis during the 20-, 30-, 40-, and 50-Hz auditory stimuli in 21 healthy subjects.

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Background: Intelligence is inversely associated with schizophrenia (SCZ) and bipolar disorder (BD); it remains unclear whether low intelligence is a cause or consequence. We investigated causal associations of intelligence with SCZ or BD risk and a shared risk between SCZ and BD and SCZ-specific risk.

Methods: To estimate putative causal associations, we performed multi-single nucleotide polymorphism (SNP) Mendelian randomization (MR) using generalized summary-data-based MR (GSMR).

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