Unraveling Posterior Cortical Atrophy: Not Seeing Things That Are There

Eight years ago, the guy could stand up at a meeting and people would sit a bit taller and listen to what he had to say. On the way home, he would sit comfortably in his 1955 DeSoto and grin and wave to passersby. Then, people started honking when he passed and they were anything but happy to see his vintage car. It was happening with increased regularity. He’d scream back. But then noticed that he’d get to a turn in the road and press his foot down heavy on the brake because he didn’t know which way to go. A short time later, the landlord complained that it looked like a three-year-old had filled out the rent check. None of the information was in the right place. His name was scrawled at the top of the check. It was random – and scary.

He was soon told not to come back to work. He got a new job and lost it on the first day when he could not complete the paperwork. Getting lost was as common as getting up in the morning. He could no longer write on a straight line. In fact, he couldn’t even see the line.

His wife knew something was wrong. They were driving across Lake Shasta. He insisted he could drive. He was in the fast lane. The tires were hugging the bumps. He was going way too slow. His hands were tight on the wheel. His knuckles were white. She is a generally calm person but was now in panic mode. She guided him into the right lane, gently holding the steering wheel. They pulled over when they got over the bridge. And that was the day she took control of the wheel – and just about everything else in her sweet husband’s life.

“There is something wrong in my brain,” he had said a few months earlier in the middle of a presentation at work. He was sobbing. His colleagues just stared.

His wife took him to an optometrist who ended the examination saying that he had a left visual field defect. A slice of his world was no longer visible. They thought it might explain why he couldn’t see lines. Why he was getting lost. Why his writing was mere scribble.

But things were getting worse and they went to a neurologist who ordered the works: a spinal tap, an MRI, a PET scan, blood draws and a few hours of cognitive testing. In the end, she said: “I don’t know what it is. It looks like Alzheimer’s but not quite.” She referred him to the Memory and Aging Center. He was 60.

Bruce Miller, director of the MAC, didn’t need the MRI results to know what was wrong with his new patient. Back in the late 1980s, his mentor was D. Frank Benson, one of the pioneers in behavioral neurology, who published a study on the first series of patients with deficits in higher visual function and sensory aphasia. The UCLA scientists were managing patients who could not see things that were right in front of them. Numbers would fly out of their heads. In time, they became cortically blind. Without any pathological clues, Benson, an astute and compassionate neurologist who would pass along those traits (among many other things) to Miller, thought it was an atypical clinical variant of Alzheimer’s. He coined the term posterior cortical atrophy.

Basically, the pathology of Alzheimer’s was showing up in the wrong place. By 2010, when this man was told he had posterior cortical atrophy, Miller and his colleagues had seen a few dozen patients. Today, the MAC follows a hundred people with this disease. Many show up in the prime of adult life – in the 50s and 60s. For most people the pathology is clear: the same amyloid plaques and tau tangles of AD show up in the back of the brain – in areas that govern vision and sensory perception. It can spread to other regions and trigger the same amnestic symptoms as those with the more common AD dementia, but it’s not always the case.

Visual disturbances in PCA remain the primary feature and some patients show a relative sparing of memory far into their disease progression. PCA can also reflect a mix of other pathologies. Patients can also share elements of other neurological conditions like Balint or Gerstmann syndrome.

Here are some of the signs:

  • Difficulty locating objects in space
  • Problems judging spatial relationships
  • Poor navigation and trouble driving
  • Problems recognizing visually-presented objects (visual agnosia)
  • Problems recognizing faces (prosopagnosia)
  • Problems understand written words (alexia) or an inability to write (agraphia)
  • Visual field deficits
  • Problems calculating numbers
  • Limb apraxia

Gil Rabinovici is one of Miller’s protégés and has taken posterior cortical atrophy under his research wing. “Diagnosing PCA can be challenging if doctors are not familiar with the constellation of symptoms,” the neurologist said. “These people are generally younger than those with amnestic AD and the atypical symptoms often lead to a long delay in diagnosis. They face a long road. Many start at the ophthalmologist’s office and can undergo cataract surgery and it takes a good ophthalmologist to figure out that this is a brain problem. Then, it takes a good neurologist to figure out that this is a neurodegenerative disease.”

Rabinovici and other PCA experts have just created the first international guidelines for the neurological condition. They hope that the signs and symptoms will help others recognize the condition.

Meanwhile, it has been eight years since the man on stage has settled into a new life. As a triathlete and a long-distance runner, he now has trouble judging the terrain and can no longer swim or ride a bike. He can still do 120 sit-ups a day. He can neither write nor read anymore. His wife dresses him in ways big and small: selecting his daily outfits and putting on his clothes and shoes, and buttoning his shirts. She accompanies him into restrooms, no matter where they are. He doesn’t recognize objects or remember what they are for. He bumps into furniture. He shuffles to balance himself. Luckily, his sense of humor is intact. He looks at his wife lovingly and still sees himself as the “stud muffin” that led her to fall in love with him.

But she also sees her guy as uncharacteristically quiet, withdrawn, disengaged. It is hard for him to find words to talk about the things he has always loved: astronomy, planets, global warming, and politics. He is not aware of all the things he can no longer do.

She knows he’s going downhill but not even the neurologists have a pulse on the trajectory of this disease. The consummate caretaker, she just goes on loving him and accepting their new life together.

 

Jamie Talan is an Atlantic Fellow at the Global Brain Health Institute, a collaborative program between UCSF and Trinity College in Dublin. She will be spending several months at UCSF’s Memory and Aging Center writing about the inner workings of the brain and giving voice to patients and the doctors, nurses, psychologists, geneticists and researchers involved in building the foundation for a whole body of non-Alzheimer dementias that are often missed, lost or ignored.