The concept you're describing is often referred to as "mass psychogenic illness" or "mass sociogenic illness." It is a phenomenon where a group of people, often within a close-knit community, share similar physical symptoms or psychological disturbances without any organic or medical explanation. The symptoms are believed to be the result of psychological or emotional distress, rather than a physical cause.
In some cases, the collective fears, anxieties, or beliefs within a population can lead to a shared sense of threat or danger, which may manifest in various ways. This can include shared delusions, where members of the group come to believe in something that is not based on reality, or even hallucinations that are experienced by multiple individuals within the group.
One famous historical example of this phenomenon is the "Dancing Plague" or "Dancing Epidemic" that occurred in various European cities during the Middle Ages. During these episodes, large groups of people were seized by uncontrollable dancing, sometimes lasting for days or even weeks. While there are several theories attempting to explain this event, it is often considered an instance of mass psychogenic illness.
Similarly, in modern times, there have been instances of "mass hysteria" or "mass panic" in which groups of people experience physical symptoms or distress based on shared fears or anxieties. Examples include cases where people believed they were exposed to toxic substances, resulting in physical symptoms like nausea, dizziness, or difficulty breathing, even when there was no evidence of actual exposure to toxins.
The power of suggestion, social contagion, and group dynamics can play a significant role in such cases. When individuals within a group witness others experiencing symptoms or distress, they may become more susceptible to developing similar issues themselves, often unconsciously.
It's important to note that these phenomena are not evidence of "made-up" or "fake" symptoms; rather, they are a manifestation of the very real psychological experiences of the individuals involved.
Overall, while collective fears and anxieties can lead to shared psychological disturbances, such occurrences are relatively rare and usually require specific conditions and circumstances to arise. They are distinct from the types of hallucinations or delusions typically associated with specific mental health conditions in individuals.