FND may exist with other problems—common comorbid symptoms of FND include fatigue, cognitive symptoms such as attention and concentration difficulties, and sleep disturbance [
1]. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID, while distinct conditions, also share these core symptoms. Myalgic encephalomyelitis (ME) is typically diagnosed by features of debilitating fatigue, postexertional malaise, nonrefreshing sleep, and cognitive difficulties [
7], while long COVID shares similar features [
8]. There are further commonalities; FND, ME/CFS, and long COVID are often associated with significant disability, but not yet diagnosed by a distinct laboratory or radiological test, and are the subject of much debate [
9].
Such debate has only heightened since the emergence of long COVID, with its associated chronic fatigue [
10-
12]. Some clinicians and researchers argue that a functional disorder paradigm may explain some cases of long COVID and ME/CFS [
13,
14], and some take the stance that it does not [
15,
16]. Some clinicians and researchers consider that these interrelated conditions have become inappropriately conflated and misunderstood, and FND has gotten mixed up and misrepresented in this debate [
17,
18]. These issues heighten vulnerability for patients with these conditions, turning to social media for information and support.