Naoki Saji

Naoki Saji
National Center for Geriatrics and Gerontology | NCGG · Center for Comprehensive Care and Research on Memory Disorders

MD, Ph.D.

About

123
Publications
5,721
Reads
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1,392
Citations
Introduction
Current research interests: Cerebrovascular diseases, Cognitive decline, Dementia, Microbiome, Neurology, Stroke
Additional affiliations
April 2015 - present
National Center for Geriatrics and Gerontology
Position
  • Managing Director
October 2011 - March 2015
Kawasaki Medical School
Position
  • Lecturer
July 2003 - September 2011
Hyogo Brain and Heart Center
Position
  • Head

Publications

Publications (123)
Article
Objective White matter hyperintensity (WMH), defined as abnormal signals on magnetic resonance imaging (MRI), is an important clinical indicator of aging and dementia. Although MRI image analysis software can automatically detect WMH, the quantitative accuracy of periventricular hyperintensity (PVH) and deep white matter hyperintensity (DWMH) is un...
Article
Background & Aims While cross-sectional studies report associations between behavioral and psychological symptoms of dementia (BPSD) and nutritional status as a modifiable factor, their causal relationship remains unclear. Therefore, this study investigated the impact of nutritional status on BPSD. Methods This study included women with mild cogni...
Article
Objective Dementia with Lewy bodies (DLB) is the second-most common form of neurodegenerative dementia after Alzheimer's disease (AD). Falls are a vital prognostic factor in patients with dementia and are a characteristic feature of DLB. This study investigated the screening potential of the fall risk evaluation for DLB and compared it with that of...
Article
Background: Previous studies have demonstrated associations between gut microbiota, microbial metabolites, and cognitive decline. However, relationships between these factors and lipopolysaccharides (LPS; molecules of the outer membrane of gram-negative bacteria) remain controversial. Objective: To evaluate associations between plasma LPS, gut m...
Article
Background: Previous studies have demonstrated associations between gut microbiota, microbial metabolites, and cognitive decline. However, relationships between these factors and neurofilament light chain (NfL; a disease-nonspecific biomarker of neural damage) remain controversial. Objective: To evaluate the associations between plasma NfL, gut...
Article
Full-text available
A lower body mass is associated with the progression of Alzheimer's disease (AD) and the risk of mortality in patients with AD; however, evidence of genetic determinants of decreased body mass in cognitively impaired older adults is limited. We therefore investigated the genetic effect of APOE-ε4 on body composition in older adults with mild cognit...
Article
Background: The association of sarcopenia with cognitive function in its specific domains remains poorly understood. Objectives: To investigate the association of sarcopenia and its components with neuropsychological performance among patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Design: Cross-sectional design. S...
Article
Objective Previous studies have shown associations between the gut microbiota, microbial metabolites, and cognitive decline. However, the effect of the dietary composition on such associations has not been fully investigated. Methods We performed a cross-sectional sub-analysis of data from our prospective hospital-based cohort study. We assessed t...
Article
Relationships between hearing impairment (HI) and dementia have been reported in elderly adults, and there is growing evidence that HI is an independent modifiable risk factor for dementia. However, there is insufficient evidence to recommend the use of hearing aids to reduce the risk of cognitive decline. To address these issues, we are currently...
Article
Objective The influence of living alone on multiple food and nutrition behaviors across a range of ages and genders has not been sufficiently investigated. Moreover, no studies have described both dietary status and medical examination findings in persons living alone. We investigated dietary habits and medical examination findings in persons livin...
Article
Existence of a relationship between hearing impairment (HI) and disability or dementia has been reported in older adults, and there is growing evidence to suggest that HI may be an independent modifiable risk factor for dementia. Nevertheless, there is insufficient evidence to recommend the use of hearing aids to reduce the risk of cognitive declin...
Preprint
Full-text available
Background Previous studies have shown associations between the gut microbiota, microbial metabolites, and cognitive decline. However, the effect of the dietary composition on such associations has not been fully investigated. Methods We performed a cross-sectional sub-analysis of data from our prospective hospital-based cohort study (the Gimlet s...
Article
Background Recent studies have demonstrated an association between the gut microbiome and cognitive function. However, the associations between the gut microbiome and brain parenchyma damage, and their underlying mechanisms, remain unclear. Materials and Methods We performed a cross-sectional sub-analysis using data from our prospective cohort stu...
Article
Full-text available
Background Hearing impairment (HI) is associated with dementia. However, the cognitive screening tasks effective in older community dwellers presenting with HI are unclear. Methods We retrospectively and cross-sectionally investigated the associations between HI and cognitive function assessed with screening tasks using data from two healthcare ch...
Article
Background: Very few studies have investigated the impact of cognitive frailty in clinical settings, especially in memory clinic populations. Objective: To examine the impact of cognitive frailty on activities of daily living (ADL), cognitive function, and conversion to dementia among memory clinic patients with mild cognitive impairment (MCI)....
Article
Full-text available
Dysregulation of the gut microbiome is associated with dementia. However, the relationship between microbiome-associated metabolites and dementia has yet to be identified. Outpatients visiting a memory clinic in Japan enrolled in this cross-sectional study; 107 subjects were eligible for the study, 25 of which had dementia. We collected demographic...
Article
Dysregulation of the gut microbiome is associated with several life-threatening conditions, and might therefore represent a useful target for the prevention of dementia. However, the relationship between the gut microbiome and dementia has not yet been fully elucidated. Here, we recruited outpatients visiting our memory clinic to participate in thi...
Article
Full-text available
Recent studies have revealed an association between the dysregulation of the gut microbiome and dementia. However, whether this dysregulation is associated with mild cognitive impairment (MCI), an early stage of cognitive decline, in patients without dementia remains unclear. We performed a cross-sectional analysis to determine the association betw...
Article
Background: Cognitive frailty (CF) is defined as simultaneous presence of physical frailty (PF) and cognitive impairment among older adults without dementia. Although white matter hyperintensities (WMH) as expressions of cerebral small vessel disease are associated with physical and cognitive decline and could manifest as CF, this association rema...
Article
Full-text available
We examined the nutritional status and its association with behavioral psychiatric symptoms of dementia (BPSD) among 741 memory clinic patients (normal cognition (NC), 152; mild cognitive impairment (MCI), 271; early-stage Alzheimer disease (AD), 318). Nutritional status and BPSD were assessed using the Mini Nutritional Assessment Short-Form (MNA-S...
Article
Background: The gut microbiota is associated with several life-threatening conditions andthus might represent a useful strategy for the prevention of dementia. However, the association between gut microbiota and dementia has not yet been fully clarified. Hypothesis: There are differences in the components of gut microbiota between demented and non-...
Article
Full-text available
Dysregulation of the gut microbiome is associated with several life-threatening conditions and thus might represent a useful target for the prevention of dementia. However, the relationship between the gut microbial population and dementia has not yet been fully clarified. We recruited outpatients visiting our memory clinic to participate in this s...
Article
Objective: The aim of this study was to clarify the association of physical frailty with behavioral and psychological symptoms of dementia (BPSD) and caregiver burden in patients with Alzheimer's disease (AD). Methods: The subjects were 1,193 AD patients who presented to the Memory Clinic at the National Center for Geriatrics and Gerontology of...
Article
Full-text available
Introduction Non-valvular atrial fibrillation (NVAF) is known as a robust risk factor for stroke. Recent reports have suggested a risk of dementia with NVAF, but much remains unknown regarding the relationship between this mechanism and the potential protective effects of novel anticoagulants (direct oral anticoagulants (DOACs), or non-vitamin K or...
Article
Full-text available
The amount of attention to age-related hearing loss (ARHL) has been growing, not only from the perspective of being one of the most common health conditions affecting older adults, but also from the perspective of its relation to cognition. Results from a number of epidemiological and laboratory studies have demonstrated a significant link between...
Article
Full-text available
Background/Aims Behavioral and psychological symptoms of dementia (BPSD) are exhibited in most patients with Alzheimer disease (AD). Although white matter hyperintensity (WMH) is often observed with AD, the precise role of WMH in BPSD remains unclear. The current study aimed to identify the impact of regional WMH on specific features of BPSD in per...
Article
Since the operational definition of "cognitive frailty" was first proposed in 2013 by the International Academy of Nutrition and Aging and the International Association of Gerontology and Geriatrics, several studies have been carried out using this cognitive frailty model. In this review, we examined the available clinical and epidemiological evide...
Article
Background: The mechanism of progressive neurological deficit in patients with recent small subcortical infarcts has not yet been clarified. Inflammatory biomarkers and the use of cilostazol may be associated with this phenomenon. Methods: Between May 2013 and April 2014, we evaluated consecutive first-ever patients with stroke due to recent sma...
Article
Background: Weight loss is frequently observed in patients with Alzheimer's disease (AD); however, the underlying mechanisms are not well understood. Objects: To clarify the associations between nutritional status and AD-related brain changes using Pittsburgh Compound-B (PiB)-PET, fluorodeoxyglucose (FDG)-PET, and structural MRI. Methods: The...
Article
Full-text available
Background Instrumental activities of daily living (IADL) start to decline during the progression of amnestic mild cognitive impairment (aMCI) to Alzheimer disease (AD). Cognitive and physical decline are involved in the loss of functional independence. However, little is known about AD-related neural change that leads to IADL impairment. The purpo...
Article
Background: Urinary incontinence (UI) is frequently observed in patients with Alzheimer's disease (AD). Although previous works highlight the association between frontal lobe-related function and UI, causal relationship is unclear. Objects: To clarify the longitudinal association between frontal lobe function and the incidence of UI at 1 year in...
Article
The aim of this study was to determine whether pulse wave velocity (PWV), a marker of vascular endothelial impairment and arteriosclerosis, predicts future ischemic stroke in patients who developed acute lacunar infarction. Patients with a first-ever ischemic stroke due to acute lacunar infarction were enrolled in this study. An oscillometric devic...
Article
Full-text available
The safety and efficacy of non-vitamin K oral anticoagulant (NOAC) compared with warfarin in treating patients with non-valvular atrial fibrillation (NVAF) who developed acute ischemic stroke or transient ischemic attack (AIS/TIA), particularly those receiving tissue-plasminogen activator (tPA) therapy, remains unclear. Between April 2012 and Decem...
Article
Background: The aim of the present study was to clarify the effect of glucose profiles after stroke, which was assessed by a continuous glucose monitoring (CGM) device. Methods: Acute ischemic stroke patients within 24 h of onset were prospectively studied. CGM was performed for 72 h after admission. CGM parameters were evaluated as follows: (1)...
Article
Full-text available
We report the case of a 73-year-old man who developed bilateral vertebral artery dissection after a craniocervical contusion. He fell into a side ditch, and suffered bruising on the head and neck. He was diagnosed with a sixth cervical vertebral fracture, cerebellar infarction, and bilateral vertebral artery dissection, and was treated conservative...
Article
Frailty is a predictor of functional decline, falls, hospitalization, and mortality. Fried et al. developed the frailty index, which include 5 simple items: weight loss, weakness, exhaustion, slowness, and low activity. Likewise, sarcopenia indicates an age-related decline in skeletal muscle mass as well as muscle function, which may result in redu...
Article
Background: To date, very little is known about the nature of sarcopenia in subjects with cognitive impairment. The aims of this study were firstly to clarify the prevalence of sarcopenia at various stages of cognitive impairment, and secondly to examine factors related to sarcopenia in men and women with cognitive impairment. Method: The subjec...
Article
A 64-year-old man developed right arm weakness and dysarthria, and was admitted to our hospital. Diffusion-weighted magnetic resonance imaging of the brain showed a high intensity area in the frontal lobe. T2*-weighted images showed multiple spotty low intensity lesions in bilateral cerebral hemispheres, mimicking cerebral microbleeds. Cerebral ang...
Article
Background and purpose: Hyperintense vessels (HV) detected on fluid-attenuated inversion recovery (FLAIR) in patients with acute ischemic stroke (AIS) indicate cerebral hypoperfusion. However, the clinical meaning of changes in HV is yet to be clarified. Here, we investigated serial changes to HV in patients with AIS who received tissue plasminoge...
Article
Background: Cerebral small vessel diseases, including silent lacunar infarcts, white matter hyperintensities, and microbleeds, pose a risk for cerebrovascular disease, cognitive impairment, and the geriatric syndrome via effects on arterial stiffness. However, the vascular, physiological, and metabolic roles of arterial stiffness in cerebral small...
Article
White matter hyperintensities (WMH) are defined as cerebral white matter changes presumed to be of vascular origin, bilateral and mostly symmetrical. They can appear as hyperintense on T2-weighted and fluid-attenuated inversion recovery sequences, and as isointense or hypointense on T1-weighted magnetic resonance imaging of the brain. WMH have been...
Article
Full-text available
Cerebral small-vessel disease (SVD) is associated with renal dysfunction such as chronic kidney disease. Although cerebral microbleeds (CMBs) are common in patients with acute lacunar infarcts (ALI), the association between renal dysfunction and CMBs in such patients remains unclear. Between April 2007 and March 2013, we evaluated consecutive first...
Article
Hereditary cerebellar ataxia constitutes a heterogeneous group of neurodegenerative disorders, occasionally accompanied by other neurological features. Genetic defects remain to be elucidated in approximately 40% of hereditary cerebellar ataxia cases in Japan. We attempted to identify the gene responsible for autosomal recessive cerebellar ataxia w...
Article
We herein report a case of ischemic stroke in a 69-year-old man with unilateral moyamoya vessels originating from the proximal portion of the left middle cerebral artery. In addition, digital-subtraction angiography demonstrated a string-of-beads-like appearance in the cavernous portion of the left internal carotid artery. A genetic analysis reveal...
Article
Hereditary hemorrhagic telangiectasia (HHT) occasionally can be discovered in patients with cerebrovascular disease. Pulmonary arteriovenous malformation (PAVM) is one of the complications in HHT and occasionally is causative for life-threatening embolic stroke. Several genetic defects have been reported in patients with HHT. The broad spectrum of...
Article
Full-text available
The ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) are surrogate markers of arteriosclerosis. However, their roles in patients with acute ischemic stroke remain unclear. From October 2003 to September 2011, we enrolled patients with arteriosclerotic ischemic stroke (AIS) exhibiting larg...
Article
Full-text available
Background: We conducted a multicenter retrospective cohort study to elucidate the characteristics of intracranial hemorrhage (ICH) in patients with atrial fibrillation treated with non-vitamin K antagonist oral anticoagulants (NOACs). Method and results: We sent a questionnaire to the directors of 241 stroke centers in Japan to establish the cl...
Article
Background and Purpose: Hyperintense vessels (HV) on FLAIR detected in patients with acute ischemic stroke indicate cerebral hypoperfusion. Thus, vanishing of HV should indicate reperfusion. We investigated serial changes of HV in patients who received tissue plasminogen activator (t-PA) therapy, comparing changes with clinical outcomes. Methods: W...
Article
Half of acute stroke patients have poor outcomes at 3months even when treated with intravenous thrombolysis using tissue-plasminogen activator (t-PA) therapy. The aim of the present study was to evaluate the impact of the susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) T2* at the proximal portion of the middle cerebral artery (...
Article
Objective We investigated whether brain natriuretic peptide (BNP) levels could be used as a marker to predict recurrent stroke in ischemic stroke survivors. Methods From April 2007 to March 2011, consecutive patients within 24 hours of onset of ischemic stroke were prospectively enrolled, and admission plasma BNP levels were measured. Survivors we...
Article
We report an IE-related stroke patient receiving hemodialysis with the ICA stenosis.•The ICA stenosis progressed in-situ, finally leading to occlusion.•Autopsy revealed multiple vegetations on the mitral valve and the ICA thrombus.•Platelet-rich thrombus with Gram-positive cocci was confirmed by pathological examination.•The patient had pyogenic ar...
Article
Background: Intravenous thrombolysis using the tissue-type plasminogen activator (t-PA) is contraindicated for patients with a history of intracerebral hemorrhage (ICH). T2*-weighted magnetic resonance imaging (MRI) is able to detect asymptomatic ICH. If there is an association between asymptomatic ICH on T2* before t-PA therapy and ICH after t-PA...
Article
Background: Whether brain natriuretic peptide (BNP) levels are associated with early recurrent stroke in cardioembolic stroke patients was investigated. Methods: From January 2010 to March 2014, consecutive patients within 24 hours of onset of cardioembolic stroke were prospectively enrolled, and admission plasma BNP levels were measured. Recurr...
Article
Full-text available
Background: Chronic kidney disease (CKD) is associated with cerebral small vessel diseases (SVD) and predicts stroke, cardiovascular events and mortality. However, its association with recent small subcortical infarcts (RSSI), a novel subtype of cerebral SVD, has not yet been established in stroke patients. The aim of this longitudinal study was t...
Article
Transient neurological attacks (TNAs) are attacks with temporary (< 24 h) neurological symptoms, and reported in 1975. Ischemic cerebral infarction often occurres after transient neurological symptoms which are not sometimes involved in transient ischemic attack (TIA) criteria. The purpose of this study was to clarity transient neurological symptom...