I get asked this question a lot: What is sensory processing disorder?

And I’ve learned that people want the short answer.

So okay, here it is. The short answer is that it’s about making sense of the senses. The brain has the task of doing this, and it ain’t easy.

Think about it. Every bit of information from all of the body’s senses, inside and out — your poor little brain has to process this, and do it right, with split-second timing. Otherwise, the brain gets the wrong information.

Too much and too little

You can think of the senses as having a volume control. If the volume is up too high, then the brain gets the messages too strong. Sounds are too loud, lights are too bright, movements are too dizzying, tastes are too spicy. The brain can’t stand this excess and tries to avoid it by hiding from sensation.

But if the volume is down too low, then the brain gets the messages too weak. Sounds aren’t clear, print is hard to read, sitting still is torture, and food is tasteless. The brain craves more sensation and stimulates the body to get it.

Just part of growing up?

Sensory processing calibration is part of growing up. Babies touch, smell, taste, and hear things, and their brains gradually tune in to the volume of these messages. Toddlers move, spin, fall, and swing, and their brains learn how to feel out these movements without over-reacting or under-reacting.

So yes, sensory processing is part of growing up.

But sensory processing disorder is not. SPD is sensory processing calibration that didn’t happen in babyhood and toddlerhood. Now the kid is much older, or even now an adult, and the problems haven’t been resolved.

Which looks like…

There’s no one picture of an SPD child or adult. It’s always a combo package.

People have five feeling senses (vision, hearing, smell, taste, touch) and two movement senses (muscle awareness, balance), and each of these can be normal, over-sensitive, or under-sensitive. Most people with SPD problems have a mixed bag of normals, overs, and unders.

But here are some common features of SPD people:

• They feel unsafe in the world. Their brain gets wrong information from their bodies almost all the time. It’s depressing and disorienting. Not to mention dangerous.
• They have anxiety. Sure, doctors  treat anxiety as a disorder, but a lot of anxiety problems occur as a response to a disorder. If you feel unsafe all the time and can’t get the right information from your senses, then you’ll become anxious. You don’t need a separate disorder for that to happen.
• They avoid certain types of sensation. Some avoid certain foods or textures. Others shrink from certain kinds of movements.
• They crave certain types of sensation. Some crave movement (they can’t sit still). Others reach for the hot sauce, body contact, and loud music.
• They’re not good in sports. Sports takes split-second timing and perfect brain-body coordination. Even a simple team-sport game like soccer is overwhelming if your senses are getting the information all wrong.

Is it ADHD?

SPD and ADHD can look a lot alike if the kid is under-sensitive in either of the movement senses. That kid will crave movement all the time. The need to move can be so overwhelming that the kid can’t pay attention.

But there are some fundamental differences between SPD and ADHD. Here are the big ones:

• ADHD: no anxiety
• SPD: high anxiety
• ADHD: responds to stimulants without going nutso
• SPD: responds to stimulants but becomes certifiably insane

A life sentence?

SPD is often not a life sentence. Catch it early enough, and you can get exercises and therapies to help the kid’s brain calibrate to its senses. The therapies work very well, given enough time and effort.

Some things might not fix completely. But that’s life. Everybody has their things to deal with. SPD people generally figure out how to adapt their lives so that they can get on with living.