Experiences of Social Media Platforms' Policies and Restrictions Related to Self-Harm Content: Mixed Methods Study.

Prion disease is one of the fatal neurodegenerative diseases. It is classified under transmissible spongiform encephalopathies (TSE). The prion is formed by structural changes in the normal host protein (PrPC) and has transmissibility. The accumulation of this in the central nervous system leads to prion disease. Creutzfeldt-Jakob disease (CJD) is a representative case of human prion disease. This includes sporadic, genetic, and acquired forms, with reported cases in Japan from April 1999 to February 2021 accounting for 76.2%, 21.0%, and 2.3% respectively []. The incidence of prion disease is estimated to be a few cases per million people each year, but there have been reports of an increasing trend in the past [,]. The cases and diagnostic criteria for prion diseases are outlined in guidelines described by the Centers for Disease Control and Prevention (CDC) in the United States and the National Center of Neurology and Psychiatry in Japan [,]. Typical cases of CJD include rapidly progressive dementia, ataxia, visual disturbances, myoclonus, pyramidal/extrapyramidal signs, and akinetic mutism. In diagnosis of CJD, blood and urine tests, electroencephalogram (EEG), MRI scans, and cerebrospinal fluid examinations are conducted to distinguish prion diseases from other disorders such as Alzheimer’s disease. There is no established treatment for prion diseases until now. Early and accurate diagnosis is considered a significant challenge in understanding the progression and symptoms of the disease. Additionally, Connor et al. said that obtaining a confident antemortem diagnosis of prion disease is important for infection control purposes, for excluding other difficult-to-diagnose but potentially treatable neurological diseases, and for helping to prepare the patient and loved ones for end-of-life care [].