Shared psychosis or Folie à deux is a psychiatric syndrome in which symptoms of a delusional belief and sometimes hallucinations are transmitted from one individual to another. In one famous case where shared insanity was seen was of Ursula and Sabina Eriksson, who were Swedish twin sisters visiting the UK. When Ursula ran into oncoming traffic due to delusions, her sister duplicated her actions and stepped into the path of an oncoming car. When they released from the hospital, Sabina acted erratically and stabbed a man to death.
2. Huntington’s disease is a fatal genetic disorder that causes deterioration of a person’s physical and mental abilities during their prime working years and has no cure. Several women convicted in the Salem Witch Trials were suspected of witchcraft due to symptoms of Huntington's disease. In 2002, a woman named Carol Carr killed her two adult sons in a nursing home after she couldn't see them suffer from Huntington's disease anymore. She was sentenced for 5 years and she served 2. After release, she was told if her third son started developing symptoms she was barred from being his caregiver. A year later he was diagnosed and she had to watch her only child suffer from a distance, unable to help him.
3. Boanthropy is a strange delusional disorder in which the sufferer believes he or she is a cow or ox. It usually starts as a dream, eventually taking hold of the mind as a full-blown delusion. The most famous sufferer of this condition was King Nebuchadnezzar, who according to the Book of Daniel “was driven from men and did eat grass as oxen”.
4. There is a mental eating disorder named Pica, which is often caused by iron or other mineral deficiencies. The person suffering from it craves for things which have no nutritional value such as paper, clay, metal, chalk, soil, glass, sand or feces.
5. A prominent cause of divorce among older Japanese couples is “retired husband syndrome.” Japanese work culture demands long hours at work, away from home, so a husband may leave home in the early hours of the morning and return home late at night. This means that a husband and wife may not interact extensively during his career and after retirement, they may feel that they are living together with someone who is a virtual stranger. Wives begin to show stress symptoms when they are made to manage their recently retired husbands who have nothing to do but bark orders at them all day long.
Suicide headaches or cluster headaches are described as the most painful condition humans are capable of experiencing. Women who do get them say the pain can be worse than childbirth. Soldiers who've had limbs blown off would rather step on another landmine than have another episode. Medical experts still aren’t sure what causes them and the only treatment known to be effective is LSD and psychedelic mushrooms.
7. Narcissistic personality disorder is a personality disorder in which there is a long-term pattern of abnormal behavior characterized by exaggerated feelings of self-importance, an excessive need for admiration, and a lack of understanding of others' feelings. They cannot accept criticism. They just can't comprehend it.
8. When people are exposed to an experience of great personal significance, particularly viewing art or natural beauty they can come down with rapid heartbeat, dizziness, fainting, confusion and even hallucinations. This psychosomatic disorder is called Stendhal syndrome. This is commonly seen in people visiting Florence after they are overwhelmed by Florentine art.
9. There exists an impulse-control disorder known as autophagia. Sufferers may experience a feeling of tension or arousal and then proceed to eat part of their body, often by simply biting and chewing compulsively. The person may feel pleasure or gratification from this. In one case, a man began by biting his own nails but ended up with such a problem that he severely mutilated his fingers.
10. There is a psychiatric condition called “koro” which is seen mostly in Southeast Asian and Chinese men, where the patient suddenly grasps his penis, fearing that it will retract into his abdomen, disappear and ultimately cause his death. Scientists consider that it is caused by psychosexual conflicts and cultural beliefs.
An unusual psychiatric disorder known as Glass Delusion swept through Europe during the late Medieval period and it consisted of people coming to believe they were made out of glass, and feared that they might shatter into pieces. King Charles VI of France suffered from glass delusions. He refused to let people touch him and wore reinforced clothing to protect himself from accidental “shattering.”
12. People with Dissociative Identity Disorder (Multiple Personality Disorder) can undergo significant changes such as the need for glasses to correct vision, gain/lose an allergy, turn diabetes on and off, and even go from drunk to sober when switching personalities.
13. Visual hallucinations are usually associated with schizophrenia or drug use, but there is a condition named Charles Bonnet Syndrome, which can cause a healthy person to experience visual hallucinations. It isn’t caused by any mental illness but caused by vision loss. One-third of the people whose eyesight starts deteriorating, experience vivid, cartoonish visual hallucinations. Victims mostly tend to see weird creatures and animals. The reason behind this is that the brain always expects sensory input from the eyes, but when it receives nothing due to vision loss; it creates its own inputs.
14. Akinetopsia or motion blindness is a neuropsychological disorder that makes its sufferers unable to perceive motion. They can still see acutely and recognize objects normally. Everything seems to be frozen in time only to “jump ahead” in time and freeze again. They often view life as a series of photographs or frozen movie reels.
15. The Fregoli delusion is a rare disorder in which a person affected by it holds a delusional belief that various people he/she meets are in fact a single person who changes appearance or is in disguise. The syndrome is usually related to a brain lesion and it is often has a paranoid nature, with the delusional person believing themselves to be persecuted by the person they believe is in disguise.
Impostor phenomenon or fraud syndrome is a psychological pattern describing individuals who are marked by an inability to internalize their accomplishments and suffer persistent fear of being exposed as a "fraud". Despite external evidence of their competence, those experiencing this phenomenon remain convinced that they are frauds, and do not deserve all they have achieved.
17. People with Misophonia are triggered by common sounds such as chewing, loud breathing or even repeated pen-clicking. It isn’t just an annoyance to them, but reactions range from discomfort to sharp anger to physical violence. It is an actual neurological disorder. There's no cure, but if one is diagnosed there are coping mechanisms that can improve one’s quality of life.
18. People suffering from Puppy Pregnancy Syndrome believe that shortly after being bitten by a dog, puppies are conceived within their abdomen. They believe that they will eventually die, especially men, who think they will give birth to the puppies through their penis. The syndrome is localized to villages in several states of India.
19. Exploding Head Syndrome is a benign condition in which an individual experiences loud unreal noises like a bomb exploding or a gunshot going off in their head when falling asleep or waking up. There is no known cause and aside from the shock, it is harmless.
20. Locked-in Syndrome is a condition in which a patient has cognitive awareness, but can’t move any body part or communicate verbally about their cognitive mental state due to complete paralysis of nearly all voluntary muscles in the body, except for vertical eye movements and blinking. A man named Richard Marsh is a rare survivor of locked-in syndrome. During his coma, he watched his wife beg doctors not to take him off of life support, and witnessed his own rough handling by the nighttime staff. Another man named Martin Pistorius woke up from a coma after 2 years but was unable to show any sign of it, and so was trapped in a lifeless state for a further 10 years whilst being fully aware. Another victim of this disease, Jean-Dominique Bauby wrote a book by blinking his left eyelid for 10 months and died 10 days after the book released.
According to a 2010 report in the journal Current Biology, a woman known only as SM is literally fearless due to a rare genetic condition known as Urbach-Wiethe disease that hardened her amygdala, part of the brain responsible for fear response. Researchers exposed her to snakes, spiders, an amusement park haunted house and horror films, none of which scared her. Researchers said that these finding could help in progress for the treatment of post-traumatic stress disorders.
22. There is a mental illness named “Münchausen Syndrome by Proxy” where a caregiver deliberately induces physical or mental problems in those who are in their care. This is typically done to gain attention and sympathy for themselves. Approximately 1% of asthma cases in children are faked by their parents. The worst case where this was noticed was of Marybeth Tinning, who is suspected of have killed all 9 of her children in a span of 14 years.
23. Morgellons disease is a delusional infestation. People affected by it become delusional and see things crawling beneath their skin and see bugs coming out of their body. They then start scratching themselves, forming sores, in order to purge their bodies of fibers that they believe is implanted in them from a certain organism. This “disease” has been reported all across the world, and even a Congressional study was conducted.
24. Sleeping beauty syndrome or Kleine-Levin syndrome is a rare sleep disorder that causes the patients to experience periods of excessive sleep episodes, which can last anywhere from 20 hours a day to a couple of days to even weeks. About 80 percent of patients are teenagers when they first experience KLS. These episodes of lengthy sleep may be proceeded by flu-like symptoms and, when they're awake, people with this syndrome may exhibit various odd behaviors, including eating excessively, hallucinating or acting childishly.
25. Jerusalem Syndrome is an intense religious psychosis that is triggered when a person who seems previously balanced and devoid of any signs of psychopathology becomes psychotic after arriving in Jerusalem. It is not endemic to one single religion or denomination but has affected Jews, Christians, and Muslims alike. An affected person may believe himself to be the coming of the Messiah or the second coming of Christ. This psychosis resolves to full recovery after leaving Jerusalem.