Is autism overdiagnosed? The question continues to generate debate, especially in light of a report from the National Center for Health Statistics indicating the prevalence of parent-reported autism spectrum disorder (ASD) among school-age children was 2.00% in 2011–2012, a 1.16% increase since 2007. The magnitude of the increase was greatest for boys and for adolescents aged 14 to 17, and researchers suggested that much of the increase in prevalence over the five-year period resulted from diagnoses of previously unrecognized ASD.
In the 20 years since I first learned of prosopagnosia, I've often wondered if some children diagnosed with ASD disorders -- particularly autism, Asperger syndrome and pervasive developmental disorder not otherwise specified -- have prosopagnosia, instead. Many characteristics associated with ASD also can occur in prosopagnosia, such as inappropriate social behavior and problems with non-verbal communication. For example, many individuals with Asperger syndrome and other ASD disorders avoid eye contact -- also a characteristic of those with prosopagnosia.
Consider this scenario: A child with prosopagnosia, or face blindness, is born into a family with "normal" face recognition. The child grows assuming that others cannot recognize faces, just as he or she cannot. Meanwhile, other family members assume the child "sees" faces just as they do. No one thinks to question the other's visual perception, even if the child sometimes acts slightly "strange," "eccentric" or even "lost" in his or her own environment.
While the child is young and primarily confined to the family circle, he or she learns to differentiate among family members by voices, gender, age and other mannerisms, assuming everyone else is navigating the world the same way. Family members may develop a protective instinct for the child, aware that he or she sometimes seems distracted, evasive around strangers or inclined to withdraw from social interaction -- characteristics that can easily apply to ASD.
It's not a stretch to imagine that concerned parents might eventually seek a professional assessment, with ASD the suspected diagnosis. In my view, it's equally likely that some children with prosopagnosia, exhibiting such characteristics, could be misdiagnosed with an ASD disorder, particularly since temporal lobe dysfunctions can be associated with both disorders.
In studying individuals with developmental, or congenital, prosopagnosia, researchers have learned that many were not diagnosed until they left home, for college or a first job, and realized for the first time that nearly everyone else they met could remember their face. As they grew, many of these children had compensated for face blindness by memorizing names, seating charts, sports jersey numbers and other routines that helped them navigate their environment at school and play, assuming everyone else was doing the same.
"People are more in tune with the possibility" that the characteristics of prosopagnosia might be mistaken for symptoms of ASD, said Jason Barton at the University of British Columbia's Human Vision and Eye Movement Lab. In fact, Barton's colleague, Brad Duchaine, whose Social Perception Lab at Dartmouth College works closely with developmental prosopagnosia, believes most of these individuals develop normal social interactions, even if their behaviors may sometimes appear a bit odd.
"There's no question that some people with developmental prosopagnosia also have social developmental issues," Barton said. "But it's not a given that if you have a problem recognizing faces you will necessarily fall into the autism spectrum. On the other hand, if a child has a diagnosis such as autism or Asperger syndrome, that person won't automatically have a problem recognizing faces."
But nearly two-thirds of those diagnosed with ASD do have problems recognizing faces, Barton acknowledged, even if they aren't completely face blind, like my husband, Chuck. Last month, researchers at Georgetown University Medical Center reported in the journal NeuroImage: Clinical that neurons in the fusiform part of the brain, which processes facial recognition, behaved abnormally in individuals with autism, causing difficulties with facial recognition. The scientists made the discovery using a form of functional magnetic resonance imaging, or fMRI, that's commonly used in prosopagnosia studies.
"One of the struggles is trying to figure out, if this is a part of the problem for some people with autism, can we retrain the way they see faces?" Barton asked. "And will that have any impact on their autism?"
The initial approach in working with such individuals is the same advice Chuck received as part of his "retraining": Look more closely at people's eyes.
"We might not be able to hang the entire fault for their social problems on the fact that individuals with autism don't look at the eyes," Barton said, "but if they do look at the eyes, will they pick up more social cues and, therefore, improve their social functioning?"
These are questions parents, and medical professionals, should ask if a school-age child is suspected of ASD -- particularly if the symptoms are mild. As Maximilian Riesenhuber, associate professor of neuroscience at Georgetown, said about the research on autism and facial recognition, huge variation exists, and some individuals with autism have no problem recognizing faces.
“But for those that do have this challenge, it can have substantial ramifications," he added. "Some researchers believe deficits in face processing are at the root of social dysfunction in autism.”