Omni Brain

Mind Hacks recently held its first AAICS (Awkward Acronyms In Cognitive Science) competition, to find the most inventive and unwieldy brain-related acronyms. I submitted a few; there was Project CHOICES (Changing High-Risk AlcOhol Use and Increasing Contraception Effectiveness Study) [link], and ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly) [link]. The acronym I thought was my best submission was also judged to be best: I won the competition! Yay!

The most AAICS was ACHOO syndrome: autosomal dominant compelling helio-ophthalmic outburst syndrome. FTW! WTF is ACHOO, you may ask? IMHO it's related to a few other conditions but without getting too OT, it's another name for photic sneeze syndrome.

Photic sneeze syndrome (sometimes inaccurately called a reflex) is a condition in which sudden exposure to bright light triggers a sneeze. It is likely genetic and congenital. Some estimate its prevalence between 18-35% of the population, but it's difficult to take accurate surveys for two reasons: one is that people who have it don't report it. They may think it's just a peculiarity (there is no disability or distress, it only appears to be risky if you're a combat pilot). Another reason is that even people who have it don't notice that they do and dismiss its existence as a ridiculous idea.

I have ACHOO syndrome but for many years had no idea what it was. It wasn't bothersome enough to discuss with my doctor and I hadn't heard anything about it. I used to jokingly think that I was allergic to sunlight. It fit with my then-goth married-to-the-night lifestyle. Creatures of the night are allergic to sunlight, right?

If so, newborn babies have the same quirk, and not only from sunlight (it's also not an allergy). A 1968 study surveyed nearly 300 newborns after obstetricians noticed that when checking vision by shining a light in their eyes after birth, some babies would consistently sneeze. The most affected group (40%) were Caucasian female newborns. The authors suggested that photic sneeze may be a useful marker for visual sensitivity later in life. Forty years later, their suggestion is still unheeded.

There are a handful of theories about the cause of ACHOO syndrome, but the most likely seems to be an abnormality in the trigeminal nerve ganglion. The optic trigeminal nerve sends signals that interact with the other nerve branches controlling nasal and facial sensitivity.

One wonders what else may be linked to light supersensitivity involving the optic trigeminal nerve. It's also implicated in migraine, and one researcher, Ronald Pies, proposed a link between photic sneeze and Seasonal Affective Disorder (SAD) which might be used as a marker. No research has been conducted, though.

Horses have their own version of ACHOO called headshaking syndrome, which appears to have similar cause and effect and follows a seasonal pattern.

Fill out the quick survey below the fold: do you ACHOO?

Refs:
The photic sneeze reflex in the human newborn: A preliminary report, Anderson et al., Developmental Psychobiology, 1968
The photic sneeze reflex as a risk factor to combat pilots, Breitenbach et al., Military Medicine Dec;158(12):806-9
Evaluation and Treatment of Headshaking Syndrome, Madigan and Bell, AAEP Convention Proceedings, 1997 Vol. 43