How Alien Hand Syndrome Works

By: Charles W. Bryant  | 
Alien hand syndrome is a rare disorder where one hand functions involuntarily.
Lee Balterman/Getty Images

Key Takeaways

  • Alien hand syndrome is a rare neurological condition where a person's hand acts involuntarily, seemingly with a mind of its own.
  • It's caused by damage to the corpus callosum or other brain regions, leading to disconnection between hemispheres and loss of voluntary control.
  • Affected individuals may experience their hand performing actions contrary to their intentions, leading to frustration and challenges in daily life.

Picture this scenario: You're napping on a breezy Sunday afternoon in the hammock of your backyard, enjoying the peace and quiet of your suburban utopia. Slowly, your left hand eases up, wraps around your neck and you awake to find your own hand locked in a kung-fu grip on your throat. You pry it loose with your other hand, finger by finger, until it relents and you're left there staring at a hand that suddenly doesn't feel like your own. While it sounds like something from a B-grade horror movie, it's actually a very odd and very real medical condition known as "alien hand syndrome" (AHS).

In this article, we'll explain exactly what alien hand syndrome is, check out the brain function behind it and examine how pop culture seems to be hooked on this unusual condition.


Exactly what is Alien Hand Syndrome?

Alien hand syndrome is a rare neurological disorder in which one hand functions involuntarily, with the victim completely unaware of its action. While the example above may be extreme, people who suffer from AHS have exhibited similar symptoms in certain cases. Less horrifying symptoms include involuntary reaching and grasping, touching the face or tearing at clothing. More extreme cases have involved involuntarily stuffing food in the mouth, preventing the normal hand from completing simple tasks and self inflicted punching or choking. While it's viewed as more of a nuisance than a medical threat, its sufferers often experience psychological problems and embarrassment and are occasionally put in harm's way as result of the renegade limb's actions [source: Turkington].

AHS differs from other conditions of involuntary limb movement in that the actions of the affected limb have purpose and are goal-oriented. The affected hand will pick up an object and attempt to use it, or will perform a simple task, such as buttoning and unbuttoning a shirt. Patients retain all sense of feeling in the alien hand, but they often describe feelings of disassociation. Patients may also exhibit strange behaviors, such as speaking to the hand, claiming demonic possession or referring to it in the third person [source: Goldberg].

Also known as anarchic hand, AHS was first identified in 1909 and there have only been 40 to 50 recorded cases since. It's believed that other instances may have been misdiagnosed as part of an existing mental health disorder. The rarity and non-threatening nature of AHS has led to infrequent research and a lack of hard data, resulting in a condition that's largely mysterious. Very recently, however, new clues have been uncovered that help pinpoint the part of the brain that is active during AHS episodes [source: Kumral].

In the next section, we'll look at the brain function behind AHS.


Brain Function and Alien Hand

Damage to the corpus collosum is at the heart of this rare disorder.

In order to understand what we know about alien hand syndrome, we should take a brief look at the brain and how it works. The human brain is divided into two hemispheres, each consisting of four different lobes, all working together to create, control and regulate speech, movement, emotion and about a billion other sub-functions. The frontal lobe is the section responsible for motor skills, like movement and speech, and cognitive functions, like planning and organization, and it's a good place to start in our understanding of AHS [source: Mayo Clinic].

Let's concentrate on the planning and organization. Let's say you want to take a sip of your morning coffee. What seems like a simple task is really a complex sequence of brain functions, starting from the moment you think, "Mmmm, coffee," until it hits your lips.


When you make the decision to sip the coffee, a signal originates in the frontal lobe that plans and organizes what must take place in order for that action to be completed. You need to reach for the cup, grasp the handle, bring it to your lips, sip and swallow, then return the cup and release your grasp.

These signals are then sent to the motor strip, the area that runs from the top of your head down to the ear, and is responsible for controlling all of your body's movement.

The frontal lobe tells the motor strip, "Hey, I need some coffee, do your thing," and before you know it, you're enjoying your nice morning roast. The key in making this happen is the successful sending of messages, thanks to the corpus callosum [source: Mayo Clinic].

Think of the corpus callosum as the brain's e-mail server, a bundle of message sending nerves that connect and share information with the two hemispheres. Alien hand syndrome is a result of damage to these nerves. This damage most often occurs in brain aneurysms, stroke patients and those with infections of the brain, but can also manifest as a side effect of brain surgery, most commonly after a radical procedure that treats extreme cases of epilepsy. When the callosum is damaged, it leaves the different sections of the brain disconnected and unable to speak to each other -- its e-mail is permanently down. With AHS, one hand functions normally, carrying out purposeful tasks without signaling the other hand, resulting in a limb that can act on its own, sometimes in opposition to the functioning side [source: Turkington].

In the next section, we'll look at pop culture and how alien hand syndrome, despite its infrequent diagnoses, has often been portrayed in books, TV and movies.


Alien Hand Syndrome in Pop Culture

Peter Sellers' earned an Oscar nomination for his comic take on alien hand syndrome in 1965's Dr. Strangelove
Silver Screen Collection/Getty Images

There have only been roughly four dozen reported cases of alien hand syndrome. It's surprising then, that the literary world and Hollywood have long touched on the condition, usually changing the cause from a banal brain injury to the more dramatic, limb-replacement-from-madman-donor scenario. There are nearly as many fictionalized cases of AHS as the real thing. This may have something to do with the fascinating quality of the condition, the mystery surrounding it or perhaps it's simply the sci-fi moniker and spooky nature.

AHS made its first big-screen appearance in 1935 in the film, "Mad Love." The storyline followed an obsessed doctor who replaced the hands of a would-be lover's husband with those of a knife-wielding murderer. Sometimes the hand is not attached to a body at all, such as the murderous hand in Oliver Stone's 1981 schlock horror film, "The Hand." Thing from "The Addams Family" was a vehicle for humor rather than treachery. Ray Bradbury wrote about AHS in his short story, "Fever Dream," as did Clive Barker, in "The Body Politic." It's been portrayed in everything from TV's "Angel" and "The Simpsons" to the home video game "Metal Gear Solid."


Its most famous portrait, however, was undoubtedly in Stanley Kubrick's 1964 masterpiece, "Dr. Strangelove." In this film, a wheelchair-bound Peter Sellers, as Dr. Strangelove, continually loses control of his right arm, which repeatedly attempts to give the Nazi Party salute before being beaten down by his left hand. Sellers' comedic struggle with alien hand syndrome has since become one of the classic moments in cinema history and AHS itself is often referred to as "Dr. Strangelove Syndrome" [source: IMDB].

Regardless of how few cases of alien hand syndrome exist, or how little we know about its cause, the mystery and intrigue of the condition will no doubt continue to inspire writers and filmmakers to explore its horrific and comedic potential.

For more information on how the human brain works and other motor-oriented medical conditions, check out the links on the next page.


Frequently Asked Questions

Can alien hand syndrome be treated or managed?
While there is no cure for alien hand syndrome, management strategies may involve therapies such as cognitive-behavioral therapy, occupational therapy and medications to alleviate symptoms and improve coping mechanisms.
Are there any cases where alien hand syndrome has led to dangerous situations or accidents?
In rare instances, alien hand syndrome can result in accidental injuries or hazardous situations when the affected hand behaves unexpectedly, necessitating safety measures and close monitoring by caregivers or healthcare professionals.

Lots More Information

More Great Links

  • Assal, Frederic. Moving with or without will: Functional neural correlates of alien hand syndrome. Annals of Neurology, July 17, 2007.
  • Goldberg, Gary. When Aliens Invade: Multiple Mechanisms for Dissociation Between Will and Action; Journal of Neurology, Neurosurgery, and Psychiatry, 2000; 68:7.
  • Kumral; Compulsive Grasping Hand Syndrome: A Variant of Anarchic Hand.
  • The Mayo Clinic.
  • Turkington, Carol; The Encyclopedia of the Brain and Brain Disorders, 2nd edition.