Mary McLaurine has the neurological disorder, developmental topographical disorientation. (Ricky Carioti/The Washington Post)

I knew I was safe.

I was mere blocks from where I’d started my walk with Otis, the beagle I was dog-sitting. That knowledge didn’t matter, though; fear and adrenaline pulsed through my veins and I began to sweat profusely, which only added to the confusion in my brain. I had no idea where I was, and my surroundings looked completely unfamiliar. It was as though I’d been dropped into the middle of a foreign land. Walking in any direction would be just a guess: Am I getting closer to or farther away from where I need to be?

I hadn’t written down the address of the home I was staying at and thus had no way to ask directions, and cellphones and GPS navigation were yet to be invented. Fortunately, a woman who approached to greet Otis knew his owners and their house. She was kind enough to walk me back. We were only four blocks away.

I was 13 when this happened, and although I knew from a much earlier age that I had more trouble than most finding my way, it was easy just to tag along and follow others. However, this experience made me realize there was something wrong with me. My life was forever changed.

What if that woman hadn’t happened by? Would I have had to knock on someone’s door and ask to use their phone to call the police? What would I tell them?How could I expect them to return me to a place if I had no address or description to provide?

I have developmental topographical disorientation, or DTD. This means I can’t form a mental map or image of my surroundings. Unlike most people, I have no internal compass. At 61, I still get lost, and it’s every bit as confounding and frightening as it was all those years ago.

“When you move around, you do so by monitoring a lot of information, you look at landmarks and you try not to bump into walls,” says Giuseppe Iaria, an associate professor of cognitive neuroscience at the University of Calgary. “There is all this processing of dynamic information. You use this to form and constantly update a cognitive map of where everything is around you.”

Brain lesions sometimes affect the orientation process, producing a condition called acquired topographical disorientation. Those of us with DTD, however, show no evidence of brain damage.

“In other words, there was no brain injury — no car accident, no brain tumor or stroke,” says Iaria, who developed the DTD diagnosis and first wrote about it in 2009. “They just didn’t develop certain skills. We have found that these people who have this condition, in which basically they get lost every day in the most familiar surroundings, have been this way all their lives.”

The brains of people with DTD function much differently from those of other people, Iaria says. Brain scans of resting DTD patients have shown decreased communication between the hippocampus and prefrontal cortices, both locations vital to spatial orientation. The two don’t work in sync with one another, which impairs navigational abilities. Iaria says this condition may affect up to 2 percent of the population.

The condition does not allow people to form a mental map of their surroundings. (Ricky Carioti/The Washington Post)

DTD was brought to light by filmmaker Michelle Coomber in the 2010 documentary “Lost Every Day,” about Sharon Roseman of Denver, who was unable to find her way around her own apartment.

Roseman had kept her condition a secret for years after receiving several wrong diagnoses including multiple personality disorder. She eventually confided in her brother, who was instrumental in her contacting Iaria. She and hundreds of others have since participated in many studies, all of which concluded there had been no stroke or other kind of damage to their brains, memory or intelligence.

I vividly remember having to adapt to my condition once I started driving. I would either follow a friend who was in a car ahead of me or I would ride as a passenger to parties and other functions. I was terrified if there was no one to accompany me when driving, even if only to the store a mile and a half away. Often, I wouldn’t return for hours.

I don’t know whether I’ve spent more time hopelessly lost within miles of my home or trying to explain to people why I cannot follow a simple set of directions. They cannot understand how it’s possible to be completely and utterly lost. “How can you not know where you are? Don’t you recognize landmarks? Don’t you pay attention while you’re driving? Can’t you read a map?”

While everyone experiences being lost at times, that is significantly different from being completely disoriented in what should be very familiar surroundings. I have spent countless hours on backcountry roads not having any idea where I was; in one case, I didn’t even know which state I was in.

In a hurry to contend with an emergency in Virginia, I left my home in Frederick, Md., at 10 p.m., heading for Alexandria, about 60 miles away. After seven long hours and with barely a drop of gas left, I began panicking, fearing I might find myself stranded on the side of the road at the mercy of whoever might stop. I found a gas station at dawn. I pulled in and had to ask what state I was in. I was in Elkins, W.Va., nearly 200 miles west of my home and far from Alexandria. I nodded politely as I grasped the dirty receipt on which the attendant had scribbled directions to presumably get me back on track. They meant nothing. I can’t follow a map or written directions. In the light of day, I managed to find my way back to the interstate, and my son met me at a rest stop near my destination to ensure I arrived safely.

I factor in “lost time” when calculating the minutes or hours needed to reach my destination, and even now with GPS devices, I’m not secure that I’ll find my way. I lose my satellite signal often and with it my feeling of security. Now, before I leave home, I always write down the address of my destination in case something happens to my phone and/or my GPS tool, and I always let someone know where I am going.

Friends and acquaintances often laugh politely when I hesitate to meet somewhere because I may get lost. “It’s right down the road! You can’t miss it: That big red house is right on the corner!” Actually, with DTD, adding landmarks to an already confusing route makes matters only further confounding.

I now offer an analogy when pressed to explain my problem: It’s comparable to asking a blind person to see the color yellow. “It’s right in front of you, you can’t miss it: It’s bright golden yellow!” Society readily accept blindness and understands its principles: A person cannot see no matter how bright the color. But because so little is known about DTD and because most of the population can easily navigate with their inner cognitive map, there’s an “idiot” stigma attached to it. Those of us struggling with this disorder are often left with feelings of anxiety, depression, isolation and self-doubt, so we keep our condition to ourselves.

My children are grown young men now, and they’re very patient and understanding. They fully comprehend the serious nature and complexities of my disorder and the dangers associated with it. They don’t take it lightly, and they have me check in frequently when I am traveling.

There is no cure for DTD, but research is ongoing. I share my story in hopes of reaching others with DTD, especially those who have it but are unaware there’s a diagnosis. I find comfort that there is a medical term and diagnosis for my condition and that it’s the focus of much-needed research. With awareness, we can break free from feelings of isolation, anxiety, self-doubt and depression.

For now, I will continue to navigate the roads much the same way I navigate life: Keep it simple and straightforward, and always have a backup plan.

Resources for people with DTD:

Facebook page: Developmental Topographical Disorientation (DTD). developed by Giuseppe Iaria, an associate professor of cognitive neuroscience at the University of Calgary, offers information and a place to discuss problems related to DTD, ask questions and post and receive updates. The website also offers an online test developed by Iaria to help determine whether you have DTD.