We all know people who say they have "no sense of direction." Yet for some people thatdescription is true in all circumstances: If they take a single wrong turn on an established route they often become totally lost.This happens even when they are just a few miles from where they live.

This condition is called developmental topographic disorientation (DTD), the inability to orient within the environment.It didn’t even have a formal name until 2009, when Giuseppe I aria reported his first case in the journal Neuropsychologia.Ellen Rose had been a patient of mine for years before I realized that she had this life-long learning disability.Like other people with DTD, she can follow a route in pieces, but it never becomes part of a larger spatial understanding.That's because she does not have a larger spatial understanding of her environment.

I asked her to draw a diagram of the second floor of the house she shares with her daughter and son-in-law.It was a difficult task for her (she lives on the first floor but is very familiar with the second).She described her effort not as a bird looking down from above, but as a spider crawling across the paper tracing a route from one room to the Ellen has always wondered what was wrong with her.She knew that when others ascribed her problems to simply not paying attention they were mistaken She worried that her problems in traveling might be a sign of something more serious than jut getting lost easily, but | had no idea what that might be.

Finding out that she had DID was a relief.Knowing that something has a name can be a liberating experience.All of a sudden it is a thing, a concept with defining characteristics.It is in a way, a kind of map.