May 21, 2025
Keio University School of Medicine
It is known that after a SARS-CoV-2 infection, some patients experience a prolonged persistence of so-called "long COVID" symptoms—such as sleep disturbances, fatigue, body aches, dizziness, difficulty concentrating, memory impairment, and shortness of breath—that were not present before the infection.
A research group led by Senior Lecturer Kenta Wakaizumi of the Department of Anesthesiology, Keio University School of Medicine, in a joint study with Associate Professor Takahiro Tabuchi of the Department of Public Health, Tohoku University Graduate School of Medicine, has revealed from large-scale epidemiological survey data that long COVID symptoms are not necessarily specific to SARS-CoV-2 infection.
It is known that various physical symptoms persist in some patients after SARS-CoV-2 infection, a condition also referred to as "long COVID." However, much about its actual nature remains unclear. Meanwhile, it is understood that symptoms similar to long COVID (long COVID-like symptoms) are also observed in patients with chronic pain—pain lasting for three months or more—who have no history of SARS-CoV-2 infection. However, no previous studies have comprehensively examined what types of long COVID-like symptoms are present in patients with chronic pain and to what extent. Therefore, this study was conducted to clarify the presence and trends of long COVID-like symptoms in patients with chronic pain. The results revealed that individuals with chronic pain have a higher prevalence of various long COVID-like symptoms—including central nervous system symptoms (e.g., memory impairment, difficulty concentrating), respiratory symptoms (e.g., cough, shortness of breath), and gastrointestinal symptoms (e.g., stomach and intestinal discomfort)—compared to those without chronic pain. Furthermore, and notably, it was also found that people with chronic pain experience more of these symptoms even when compared to those with a history of COVID-19 infection. In other words, even without a SARS-CoV-2 infection, individuals with chronic pain have more long COVID-like symptoms than those without chronic pain, and the number of these symptoms was shown to exceed that of actual long COVID patients. In patients with chronic pain, it has been reported that dysfunction of the central nervous system causes not only the prolongation of pain but also a wide variety of physical symptoms. The results of this survey suggest that in the case of SARS-CoV-2 infection, a similar dysfunction of the central nervous system may be induced in some individuals, resulting in the symptoms known as "long COVID." Even now, many patients continue to suffer from the aftereffects of SARS-CoV-2 infection. It is hoped that the findings of this research will advance the understanding of the pathophysiology of these aftereffects, leading to the development and improvement of treatments. These research findings were published in the online edition of PAIN , an international journal of pain medicine, on May 6, 2025.
For the full press release, please see below.