Rare Mental Illnesses: What Are They and Why Do They Happen?

Written By Teddy Grzybowski

Mental health awareness has grown over the years. Conditions like depression and anxiety are talked about more openly than before. However, there are many rare mental illnesses that people know very little about. These conditions require further research so scientists can better understand why they occur and how the human mind works.

Cotard’s Syndrome

Cotard’s syndrome is an extremely rare mental illness, with only about 200 documented cases worldwide. It is often connected to severe depression and is more common in women. Cotard’s syndrome—sometimes called “walking corpse syndrome”—causes people to believe that parts of their body are missing, that they are dying, already dead, or that they do not exist at all.

People with Cotard’s syndrome often withdraw from others and may stop speaking. Some experience hallucinations, especially when the condition occurs alongside other mental health disorders. Without treatment, the condition can make daily life very difficult. In some cases, it has been linked to traumatic experiences or serious illness.

Alice in Wonderland Syndrome

Alice in Wonderland syndrome (AIWS) is a neurological condition that affects how people perceive their bodies, time, or the world around them. Someone with AIWS may see objects as much larger or smaller than they really are, similar to what happens in the book Alice in Wonderland. These episodes can make reality feel distorted.

Although AIWS is considered rare, studies suggest that up to 30% of teenagers may experience short, mild episodes at some point. Most cases are temporary. Doctors usually diagnose AIWS based on symptoms, and possible causes include migraines, seizures, certain mood disorders, medication side effects, infections, or, in rare cases, brain tumors or other brain conditions.

Body Integrity Identity Disorder (BIID)

Body Integrity Identity Disorder (BIID) is a rare mental illness in which a person believes that a healthy body part does not belong to them. Even though the person knows the limb works normally, they feel it should not be part of their body. Many people with BIID wish to live without the use of that body part.

The most commonly affected body part is the leg, especially the left leg. Some individuals with BIID may feel uncomfortable using the affected body part or may avoid activities that involve it. Scientists are not completely sure what causes BIID, but research suggests it may be related to how the brain maps and recognizes the body.

Taking Care of Mental Health

Rare mental illnesses may not affect many people, but they can be life-changing for those who have them. Learning about these conditions helps reduce stigma and increases understanding. Science, therapy, and medication can help people manage mental illnesses and improve their quality of life.

As a society, we have to prioritize mental health because it affects everyone—students, families, and communities. The more stressful a situation is, the bigger the impact on our minds. The internet and social media can make stress worse by spreading negativity, and our constant news cycle often focuses on the worst events in the world. By learning about mental health, supporting research, and offering help when people need it, we can make our communities stronger, healthier, and more understanding.

Mental Health: Did You Know?