Progressive supranuclear palsy (PSP) is characterized by supranuclear gaze palsy, dystonic rigidity of the neck and upper trunk, frequent falls and mild cognitive impairment. Cerebellar ataxia is one of the exclusion criteria given by the National Institute of Neurological Disorders and Stroke and the Society for Progressive Supranuclear Palsy. As a result, pathologically proven PSP patients exhibiting cerebellar ataxia have often been misdiagnosed with spinocerebellar degeneration, specifically multiple system atrophy with predominant cerebellar ataxia (MSA-C). However, more recently, it has been recognized that patients with PSP can present with truncal and limb ataxia as their initial symptom and/or main manifestation. These patients can be classified as having PSP with predominant cerebellar ataxia (PSP-C), a new subtype of PSP. Since the development of this classification, patients with PSP-C have been identified primarily in Asian countries, and it has been noted that this condition is very rare in Western communities. Furthermore, the clinical features of PSP-C have been identified, enabling it to be distinguished from other subtypes of PSP and MSA-C. In this review, we describe the clinical and neuropathological features of PSP-C. The hypothesized pathophysiology of cerebellar ataxia in PSP-C is also discussed.

BACKGROUND: Molar incisor hypomineralization (MIH) frequently occurs in children worldwide. However, MIH prevalence throughout Japan has not yet been investigated. The purpose of this study was to clarify MIH prevalence rates and to consider potential regional differences throughout Japan. METHODS: A total of 4496 children aged 7-9 years throughout Japan were evaluated in this study. MIH prevalence rates among children were evaluated in eight regions throughout Japan. A child's residence was defined as the mother's residence during pregnancy. The localization of demarcated opacities and enamel breakdown was recorded on a standard code form using a guided record chart. Logistic regression analysis was used to evaluate whether MIH prevalence rates differed among age groups, sex, and regions. RESULTS: The overall prevalence of MIH in Japan was 19.8%. The prevalence of MIH was 14.0% in the Hokkaido region, 11.7% in the Tohoku region, 18.5% in the Kanto Shin-Etsu region, 19.3% in the Tokai Hokuriku region, 22.3% in the Kinki region, 19.8% in the Chugoku region, 28.1% in the Shikoku region, and 25.3% in the Kyushu region. These regional differences were statistically significant. Moreover, MIH prevalence rates decreased with age. No significant sex differences in MIH prevalence rates were demonstrated. CONCLUSIONS To our knowledge, this is the first MIH study carried out in several regions throughout Japan. Regional differences existed in MIH prevalence rates; particularly, MIH occurred more frequently in children residing in southwestern areas than those in northeastern areas of Japan.
Child ; Dental Enamel Hypoplasia ; epidemiology ; etiology ; Female ; Humans ; Japan ; epidemiology ; Male ; Prevalence

BACKGROUND: The burden of dementia is growing rapidly and has become a medical and social problem in Japan. Prospective cohort studies have been considered an effective methodology to clarify the risk factors and the etiology of dementia. We aimed to perform a large-scale dementia cohort study to elucidate environmental and genetic risk factors for dementia, as well as their interaction. METHODS: The Japan Prospective Studies Collaboration for Aging and Dementia (JPSC-AD) is a multisite, population-based prospective cohort study of dementia, which was designed to enroll approximately 10,000 community-dwelling residents aged 65 years or older from 8 sites in Japan and to follow them up prospectively for at least 5 years. Baseline exposure data, including lifestyles, medical information, diets, physical activities, blood pressure, cognitive function, blood test, brain magnetic resonance imaging (MRI), and DNA samples, were collected with a pre-specified protocol and standardized measurement methods. The primary outcome was the development of dementia and its subtypes. The diagnosis of dementia was adjudicated by an endpoint adjudication committee using standard criteria and clinical information according to the Diagnostic and Statistical Manual of Mental Disorders, 3rd Revised Edition. For brain MRI, three-dimensional acquisition of T1-weighted images was performed. Individual participant data were pooled for data analyses. RESULTS: The baseline survey was conducted from 2016 to 2018. The follow-up surveys are ongoing. A total of 11,410 individuals aged 65 years or older participated in the study. The mean age was 74.4 years, and 41.9% were male. The prevalence of dementia at baseline was 8.5% in overall participants. However, it was 16.4% among three sites where additional home visit and/or nursing home visit surveys were performed. Approximately two-thirds of dementia cases at baseline were Alzheimer's disease. CONCLUSIONS The prospective cohort data from the JPSC-AD will provide valuable insights regarding the risk factors and etiology of dementia as well as for the development of predictive models and diagnostic markers for the future onset of dementia. The findings of this study will improve our understanding of dementia and provide helpful information to establish effective preventive strategies for dementia in Japan.
Aged ; Alzheimer Disease/genetics* ; Dementia/genetics* ; Environment ; Female ; Humans ; Incidence ; Japan/epidemiology* ; Male ; Middle Aged ; Prevalence ; Prospective Studies ; Risk Factors