Rare brain disorders that make people think they're dead and bring other bizarre delusions

Imagine being able to feel everything another person is feeling — their pleasure and their pain? Or being convinced, despite all evidence to the contrary, that you’re dead?

These are just a few of the strange brain disorders that have plagued a rare set of people over the years. Oliver Sacks’ classic book “The Man Who Mistook His Wife for a Hat” introduced us to some of the strangest brain disorders people suffer from, but that’s only the tip of the iceberg.

Here are a few of the most bizarre mental conditions out there.

Cotard's Syndrome: This disorder makes people think that they're dead.

'Night of the Living Dead'

Mr. B was a 65-year-old retired teacher with no family history of mental illness, when he suddenly began having sad moods, stopped being able to feel pleasure, slept and ate less, and developed feelings of worthlessness. He later started having delusions that his organs had stopped working and his house was going to fall down. After an attempted suicide, he started believing he was dead.

This man suffered from a condition known as Cotard's syndrome (or Walking Corpse Syndrome), in which a patient thinks he or she is dead. Counterintuitively, in more than half of cases, these patients also think they are immortal. Treatment for the condition can include antidepressant or antipsychotic drugs, or electroconvulsive therapy.

Capgras Delusion: People with this condition think a loved one has been replaced by an imposter.

After giving birth, a 36-year-old woman developed the delusion that her son and other family members had been replaced by imposters. The delusion persisted for five years, and every treatment doctors tried failed. Finally, the woman was given electroconvulsive therapy (in which electrical shocks are passed through the brain to induce a seizure), and her psychiatric symptoms subsided.

The woman suffered from what is known as the Capgras delusion or Capgras syndrome, where you think loved ones have been substituted by imposters, robots or aliens. It usually occurs in patients with paranoid schizophrenia, but has also been seen in patients with a brain injury or dementia. It's also more common in women than men (by a ratio of 3:2).

Alien Hand Syndrome: Some people are convinced their hand doesn't belong to them.

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An 82-year-old woman suffered a stroke, and upon recovering about six weeks later, she reported that her left arm did not belong to her. Instead, she was convinced the limb belonged to her brother, who had been with her when she experienced the stroke. She felt as if the arm would not do what she wanted it to do.

This was a case of alien hand syndrome, a rare neurological disorder where a person's limb moves without their control, making them feel it does not belong to them. Sometimes, the patient may reach for objects with the alien hand, and use their healthy hand to restrain it. The condition may be caused when the connections between the brain's two hemispheres are severed, but can also happen after a stroke or other brain injury. Only about four dozen cases of alien hand syndrome have been reported.

Aphantasia: People with this condition can't picture things in their minds.

A 65-year-old man called MX suddenly lost the ability to summon up images of things in his mind after a coronary angioplasty surgery. On questionnaires, he reported not being able to visualise any images, despite the fact that he performed normally on standard tests of perception, visual imagery and visual memory.

After researchers reported this, more than 20 other people contacted them to say they had the same inability to picture things in their mind's eye. Though not yet a recognised neurological condition, scientists have eloquently dubbed the phenomenon 'aphantasia,' from the Greek word for imagination.

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