When is a doorway not a doorway?

When your brain thinks it may be a brick wall.

Freezing of gait (FOG) is one of the most frustrating symptoms of Parkinson’s disease. Imagine finding you are suddenly unable to continue walking, or to begin walking, when you want to. To add insult to injury, it tends to happen when you’re under stress – running late, trying to get onto a train or into an escalator packed with other people. It sounds horribly similar to one of my recurrent nightmares (I’m late for something vital, on the platform, train about to leave, laden with luggage, legs refusing to move. Welcome to my world…).

Not everyone with Parkinson’s gets FOG, and the usual medication (variations on dopamine agonists) don’t help much. Why it happens is a bit of a mystery. The standard explanation was that dopamine deficiency stops messages from the brain (telling the leg muscles to get on with it) from getting down the nerves to where they’re needed. But more recent research has questioned whether that’s the only thing happening.

Intriguingly, some people with PD have reported feeling ‘too big’ to get through a confined space, such as a doorway into a lift, even though they know the space is designed to be big enough for people.

Now, an ingenious experiment using differently-sized doorways has shown that the size of the space does have a significant effect, causing people who get FOG to take shorter steps, and vary their stride length more, as they approach a narrower entrance. It seems perception of space is having a direct effect on the way these people walk, as if the brain is slamming on the brakes to stop them from walking into a wall. I summarised the study for the journal where it appeared, the snappily-titled Journal for Neurology, Neurosurgery and Psychiatry.

This reminded me of something I experienced as a cub reporter on my local newspaper, many years ago. The local Territorial Army had offered to donate to our Christmas appeal, if the paper could find a willing mug to spend a weekend on a TA induction course. Naturally, the editor looked no further than ‘Challenge’ Anna.

All went reasonably well until the assault course. More precisely, the water jump. In classic showjumping fashion, I ‘refused’ the jump three times, gallantly running up to the edge then stopping dead. Finally, much embarrassed, I forced myself to override the ‘Stop! Now!’ messages in my head. And landed in the water, of course. That’s what happens when you do the run-up with your handbrake on. I wonder if the same sort of thing is happening to Parkinson’s patients.

Image: From Jessicamulley’s photostream on Flickr, with Creative Commons License.

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