Autism’s high rate of photosensitivity

Young people with autism spectrum disorders (ASD) are far more likely than the rest of the population to be photosensitive–susceptible to visually triggered seizures from flashing light, video games, and other strong visual stimuli. Results from a new study made public last week at the American Epilepsy Society annual meeting showed that fully 25 percent of those age 15 and up with ASD are photosensitive. In contrast, the prevalence of photosensitivity among typical young people is said to be 1 in 4,000 (although I believe this is an underestimate).

For some time I’ve suspected that the rate among ASD young people is elevated, and I’ve been attempting to find funding for a study that would examine young people with ASD and their risk of seizures from video games. Here are some reasons why I believe video games pose a particularly acute seizure risk to young people with autism:

  • This population develops classic epilepsy at significantly higher rates than the general population
  • Children with ASD have very high rates of sensory processing disorders, including difficulties with visual processing
  • Children with ASD tend to spend their leisure time with electronic media, and they exhibit a preference for animated material, thus they are likely to be heavy users of video games

Not only are young people with ASD at higher risk of visually induced seizures, they are also less likely to have their seizures noticed and properly identified:

  • The unusual repetitive and nonresponsive behaviors that are common in individuals with ASD can be difficult for an observer to distinguish from seizures
  • In children with ASD, impaired executive function, energy, mood, attention, and cognitive ability resulting from seizures might be masked by pre-existing chronic deficits in these functions

My guess is that photosensitivity among young people with ADHD (attention deficit hyperactivity disorder) is probably higher than average, too, because of these same factors.

Here’s why this matters so much: Although it would be difficult to change game usage habits, parents of children with autism should exercise particular caution in allowing exposure to visually overstimulating images. Reducing or eliminating visually induced seizures could result in noticeable improvements in their children’s daily functioning. The last thing these vulnerable kids need is added interference, due to seizures, with cognitive and behavioral flexibility.

The study announced last week is the first to look at the photosensitivity rate in autism. It was performed at Children’s Hospital in Boston, where researchers investigated the EEG histories of children diagnosed with ASD. More research is certainly warranted, particularly since the photosensitivity assessments were done the usual way, using photic stimulation with a strobe light. Photic stimulation may show a person’s vulnerability to seizures from a strobe light, but a strobe does not recreate the experience of exposure to a video game screen. Some individuals who do not demonstrate an EEG response to the strobe may nevertheless experience seizures provoked by video games.

NOTE:  Read more on autism and seizures from sensory overload in this post from 2012. You may also want to read this post on ADHD in connection with and video games and seizures.

What affects your odds of visual sensitivity?

Photo courtesy

Do video game seizures worry you in particular? Should they?

Nobody knows the percentage of people whose sensitivity to flash and patterns could cause seizures. To find out with any statistical accuracy, researchers would need to do EEG testing with photic stimulation and patterns on large numbers of people. A population screening would be difficult due to sheer logistics and cost – attaching and removing EEG electrodes is a labor-intensive process as is properly performing the test. Pattern testing is rarely offered in the US In addition there are ethical considerations, since the photic stimulation could provoke a seizure.

Studies have found that 3 to 5 percent of epilepsy patients test positive for photosensitivity (whether or not they experience visually induced seizures). As I’ve noted previously, it’s really not known what percentage of the population without epilepsy (spontaneous seizures) is at risk for experiencing seizures induced by visual stimuli.

So, what known biological factors place you at higher risk for photosensitivity? These are things you can’t, in general, do much about:

  • Being female
  • Age 7 – 25
  • Parent or sibling with photosensitivity
  • Parent or sibling with febrile seizures
  • A specific form of epilepsy, juvenile myoclonic epilepsy
  • History of concussion
  • History of frequent headaches
  • Need for corrective eyeglasses
  • In those with epilepsy, a history of myoclonic, tonic-clonic, or absence seizures
  • Learning, behavioral, or psychiatric difficulties

These factors were ascertained in studies primarily by Graham Harding and Peter Jeavons in the UK and Dorothée Kasteleijn-Nolst Trenité in the Netherlands, leading researchers in photosensitivity and visually-induced seizures.

Note that studies measure the presence of a well-defined “photoparoxysmal” EEG pattern during exposure to photic stimulation (and sometimes, striped patterns). Its presence is a laboratory finding that does not invariably mean the test subject will experience seizures when exposed to flashing light and other visual provocation in everyday life.

Sensitivity in the same individual is affected by additional variables over which you have some control, such as fatigue, alcohol, distance away from the screen, etc.

One eye at a time: prevent seizures with an eye patch

an eye patch to protect against video game seizuresIf video games cause you to have seizures, there are certain things you can do to prevent them. The standard recommendations by doctors are:

  • Avoid exposure – stay away from any games that provoke seizures
  • Limit exposure by taking frequent breaks, sitting at a distance from the screen, and turning down the screen brightness setting
  • Avoid playing when fatigued, stressed, or sleep-deprived
  • Avoid caffeine and alcohol, which lower the brain’s seizure threshold
  • Certain anti-convulsant drugs may help, particularly Depakote (valproate), Lamictal (lamotrigine), Topamax (topiramate), Keppra (levetiracetam), and Frisium (clobazam), a benzodiazepine not yet approved by the FDA for use in the US
  • Cover one eye

Let’s say you have seizures only from video games. You may not want to start taking anti-seizure medications, which have many side effects. You also may not feel like taking breaks during play, staying far from the screen, or limiting your caffeine and alcohol. A simple way to protect yourself from visually induced seizures is to cover one eye with a patch during gaming.

Researchers have found that if only one eye is exposed to the flickering screen, a smaller area of the brain’s cortex is affected than when both eyes are exposed. The difference is significant enough to greatly reduce the likelihood of a seizure. You may need to try covering first one eye while you play and then the other eye, to determine if there’s a difference in the effectiveness — but covering either eye may be equally effective. Simply closing both eyes (without covering them) in the presence of flashing light does not provide seizure protection because the light penetrates the eyelids. (This is why, when photic stimulation is performed as part of an EEG, the eyes are closed for part of the procedure.)

Note:  For those who have an addiction to video games, the eye patch may not work. Photosensitivity could be at the root of the game addiction — because a compulsive attraction to the screen (or other seizure-provoking visual stimulus) is one symptom of photosensitivity. The uncontrollable attraction seems to be a related to an impulse to provoke seizures. In such cases, those who try the eye patch are unlikely to tolerate using it and will remove it. If you can put up with the patch, though, you are probably not going to need additional protection from video game seizures. Given the low cost of an eye patch (about $3.00 at drug stores), absence of side effects, and lack of  lifestyle constraints, this could be a solution worth trying.

How reliable is photic stimulation testing?

Most people who experience video game seizures have a condition called photosensitivity, whereby flashing or flickering light disrupts the brain’s normal electrical patterns and produces epileptic discharges. For these people a bright light flashing at certain frequencies (the number of flashes per second) can lead to the firing patterns of spikes and waves that occur during seizures. In the 1940s scientists discovered that a flashing strobe light can cause the brain to generate abnormal discharges that can be detected on EEG.

So as part of a routine EEG, a strobe light flashing at a range of frequencies is placed in front of the patient. The procedure is called intermittent photic stimulation, or IPS. IPS is the most widely used method of assessing susceptibility to visually induced seizures. The EEG and patient are watched closely, and if abnormal discharges or unusual symptoms appear, testing at that frequency stops right away, before a seizure develops.

Unfortunately, as with so much of the data used in seizure diagnostics, there is a lot of uncertainty about the meaning of photic stimulation test results. A negative result when testing for photosensitivity means simply that no seizure-like discharges were detected on EEG scalp electrodes and/or judged significant under the IPS testing conditions that were used. A positive finding may indeed point to vulnerability to seizures from flashing visual stimuli. However, in as many as 8 percent of the non-epilepsy population, particularly in children and adolescent girls, IPS produces a positive result that may have no clinical significance. A positive test for photosensitivity suggests (but does not prove) the following:

  • Because photosensitivity is characteristic of certain types of epilepsy, the patient may have one of those types. However, some people who never have seizures of any kind produce these discharges in the presence of a strobe light.
  • Since these abnormal discharges appear in response to a flashing light, the patient may be more likely to experience seizures when exposed to other sources of flash and flicker. The patient should be cautious about exposure to these visual stimuli

Compounding the weaknesses of EEG as a diagnostic tool for seizures, many procedural issues affect the accuracy of EEG results for determining photosensitivity. Results can be influenced by many things, including:

  • The type of strobe light used, including its shape and how diffuse the light is
  • The distance of the strobe light from the patient’s eyes
  • Whether the patient’s eyes were open or closed when the flashes and discharges occurred
  • Which flash frequencies were used (some people have an abnormal response only to a narrow range of frequencies)
  • The brightness of the flash
  • The wavelengths of the strobe light—the presence of certain colors in it
  • The assessing physician’s interpretation of the EEG—how abnormal are the altered wave patterns?
  • The assessing physician and the technician’s observations of the patient’s symptoms/behavior during the procedure
  • Whether the patient’s symptoms/behavior during the procedure are considered along with the EEG record

Some people who have seizures from video games do not show an abnormal response to photic stimulation. After all, the experience of playing a video game isn’t the same as viewing a pulsating strobe light. Other diagnostic tests for sensitivity to the visual experience of playing a video game — the movement of patterns and rapid fluctuations of colors — have been developed but are not widely available.

Update, 7/23/2014:  Please read here about a new study that found only 6.2% of patients with a history of visually induced seizures showed a positive result on EEG during photic stimulation.

Navy pilot loses flight status after video game seizure

photosensitive pilot has first seizure from video gameA former Navy pilot permanently lost his flight status after experiencing a seizure while playing the game Oblivion: The Elder Scrolls IV on a Sony Playstation 3. John Ryan McLaughlin, an F-18 pilot based in San Diego, also broke a bone in the incident. McLaughlin has filed suit against the game manufacturer, Bethesda Softworks, and Zenimax Media, its corporate parent, as well as Sony. Read the story here.

Note that pilots are very, very carefully screened for possible seizure disorders–using photic stimulation, which really can’t replicate the visual experience of a video game. I have to wonder how the game forums will respond to this…usually these commenters love to blame the parents of children who have video game seizures, claiming everyone should have anticipated it would happen. This very sobering case involves someone highly trained to defend our country, who’s been tested up and down to detect even the hint of a seizure problem, who now can’t use his flight training anymore. Ever. Are the game forums going to blame a guy who’s been certified seizure-free for not paying attention to a warning in the game’s user manual? Or maybe find his parents responsible?

Read more about lawsuits filed by consumers who experienced seizures from video games.