Rare Mental Disorders That Exist

Rare Mental Disorders That Exist

It is never enough to stress the importance of mental health and wellness and removing the unwarranted stigmas that are often associated with the various psychological conditions people suffer from. It is only through exposure that people get an opportunity to have a meaningful dialogue about mental conditions that plague many people in the world. While most of us have heard about some of the most common mental disorders, such as schizophrenia, bipolar disorder, obsessive-compulsive disorder (OCD), depression, and others; there are many unusual psychological conditions that are usually neglected due to the fact that they are very rare or bizarre; and thus they remain unknown. Here we discuss some of these uncommon or rare mental disorders that are affecting ordinary people, yet many of us know little about them or have never even read about them.

Rare Mental Disorders That Exist

Alien Hand Syndrome

Hearing the name of this rare mental disorder, you might remember the movie Idle Hands. Alien Hand Syndrome is a mental disorder that occurs when a person’s arm or hand tends to move involuntarily without the cognitive control of the person. The hands can also grab hold of things without you realizing what it is doing. Alien Hand Syndrome happens when there is a conflict between the two parts, left and right, of the brain, or when there is some mix-up that happens between brain wires. Damage to the brain can also cause alien hand syndrome. Alien hand syndrome is often deemed to be traumatic for the sufferer as he or she becomes terrified of what their hand can do in public. Living with a feeling that your own hand is foreign or has a will of its own is not easy. Individuals suffering from alien hand syndrome do continue to experience normal sensation in their hands. Often patients end up personifying the limb as a different entity. The other hand, though, continues to remain unaffected and functions normally and under the control of the individual.

Alice in Wonderland Syndrome/Micropsia/Todd Syndrome

Often referred to as Alice in Wonderland Syndrome, micropsia is a condition that is a visual neurological illness. People suffering from micropsia view an object to be much, much smaller than it is in reality. In this rare mental disorder, a patient’s sense of body image, space and/or time becomes distorted. In this rare mental disorder, patient may suffer hallucinations, an altered sense of velocity, or sensory distortions. Micropsia is caused by an abnormality in the way the brain interprets the information passed on from the eyes.

The most common symptoms of Alice in Wonderland syndrome is altered body image, in which patients become confused about the shape and size of their body parts. Patients can view objects to be far away or extremely close at the same time. These symptoms, in turn, trigger a panic attack or a fear response. Micropsia is also associated with brain tumors, schizophrenia, substance abuse, and frequent migraines. Migraines are actually an important characteristic of this illness and it can further affect other senses of the patients, such as touch and hearing. This rare mental disorder can even affect children as small as five years.

Apotemnophilia or Body Integrity Identity Disorder

Apotemnophilia causes an individual to want to amputate healthy body parts. Not much is actually known about this rare mental disorder except that it exists and is brought about by neurological abnormalities. Patients affected by apotemnophilia feel an overwhelming urge to amputate their own limbs, or even damage their limb so that it can be amputated surgically. Apotemnophilia is related to damage to the right parietal lobe in the brain. People suffering from Apotemnophilia do not tend to seek treatment as they believe that there is nothing wrong with them. However, aversion and cognitive behavioral therapies are known to help in treating apotemnophilia.


Erotomania is rare mental disorder, which involves taking infatuation to a different level altogether. Erotomania is a delusional condition in which the sufferer thinks that someone, usually who is considered to be ‘out-of-reach’ or of a higher social status such as a celebrity, is in love with them. The patient suffering from erotomania further feels that this person is making advances towards them by sending them secret signals or messages, such as special glances, through the media or even through telepathy.

In return, the patient then starts to return this alleged love by attempting to visit or get close to the unsuspecting person or starts to send letters even. Erotomania can actually be quite a scary condition, as the patient’s feeling is so strong and overwhelming that when their perceived lover denies their affection or their advances, the patient still remains convinced of this ‘secret love’. The delusion is extremely difficult to break and the patient will continue to think that the person is attempting to hide their love from the world. Erotomania can often be confused with ‘obsessive love’ or hypersexuality. However, they remain separate conditions and are not related to Erotomania, which comes under a rare psychological condition.


A rare psychopathological condition, Lycanthropy makes a person believe that they are an animal or being transformed into one. This is classified as a self-identity disorder and it is further segmented into different types. For example, boanthropy is the condition wherein a person thinks of himself to be an ox or a cow and it can reach such levels where the individual even starts going down on all fours to chew grass. Researchers believe that this rare mental disorder generally tends to originate in a dream sequence, before slowly enveloping the entire conscious mind of the sufferer, making them truly believe that they have become a dog or even a sloth.

Self-Cannibalism or Lesch-Nyhan Syndrome

There is nothing scarier than the brain telling you to consume your own body. Self-cannibalism or Lesch-Nyhan Syndrome is a rare mental illness in which the patient begins to consume their own body parts in a condition called autosarcophagy. The person can also start exhibiting self-mutilating behavior. Self-cannibalism affects the muscles, joints, and the brain of the person. This rare mental disease is caused by the overproduction of uric acid in the body. It also commonly leads to compulsive finger and lip biting. In a majority of such cases, patients need to have their teeth removed in order to stop them from chewing off their lips, tongue and cheeks. The condition occurs only in boys and is related to impulse control disorders. Self-cannibalism can be life-threatening, if left untreated.

Walking Corpse Syndrome or Cotard’s Syndrome

Walking Corpse Syndrome, the name itself is enough to raise eyebrows and send chills down your spine. This is not a disorder where you feel ‘dead tired.’ Walking Corpse Syndrome is a rare mental condition where a person believes he or she is actually dead, or that they simply do not exist. This condition is linked to depression and to people who are chronically sleep deprived or are suffering from drug psychosis. Walking Corpse Syndrome still remains largely misunderstood by science and no one truly knows what exactly its cause is.

There is also a flip side to this syndrome- many people feign immortality. The condition was discovered by neurologist Jules Cotard, who then went on to describe this condition as ‘The Delirium of Negation’. Walking Corpse Syndrome is very much similar, or even connected to, Capgras Syndrome, which is a condition where an individual thinks that someone in their life has been replaced by an impostor. This happens when a division occurs in the brain between the parts that actually associates emotional responses with visual face recognition. Similarly, a person suffering from either Capgras syndrome or Cotard’s syndrome may fail to even recognize themselves and becomes truly convinced that he or she does not exist.

Walking Corpse Syndrome starts with self-hatred and can go on to become stronger and stronger, resulting in chronic depression and severe delusions.


So these were some of the uncommon or rare mental diseases, which many of you must be reading about for the first time; which nevertheless exist in today’s society. This was a small attempt to educate the readers about some unknown and uncommon mental disorders, which if left untreated are of great danger to the patient as well as to the society.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 4, 2018

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