Can’t put a name to a face? You may have the same ailment as Brad Pitt. The actor says he has facial blindness. Turns out, it’s a rare but real problem when it comes to visual processing.

Rush neurologist Andrew Dorsch said he has rarely seen cases of prosopagnosia, or face blindness, during his career.

“I can count the number I’ve met in my clinical experience, and it’s probably about two,” he said. “It is something you learn about in medical school but rarely hear or see.”

What is prosopagnosia?

“It’s an inability to recognize faces,” Dorsch said. “It could be faces you don’t see all that often. A more severe case may be that you don’t recognize familiar people or even gets to the extent where you don’t recognize your own face in the mirror.”

There are different causes. Patients may experience face blindness due to a neurodegenerative disease, such as Alzheimer’s disease, where the impairment is part of a constellation of symptoms. Some develop the condition as a result of damage caused by a stroke, hemorrhage or traumatic brain injury.

“Other people were born with it. That’s just the way their brain develops,” Dorsch said.

Formal neuropsychological tests can help diagnose the impairment which boils down to a problem with visual processing.

To compensate, patients often use visual cues.

“They focus on an eyebrow, a nose, they look at how people’s hair is or the way that they walk or the tone of their voice,” Dorsch said. “People with this condition may not even know they have it because they have developed these cues over time until something else happens and then it becomes much more obvious.”

There are different types of “agnosias” when it comes to classifying visual processing problems including difficulty with recognizing colors, body parts and identifying oneself in space.