What Is It, Causes, Diagnosis, and More
Author: Nikol Natalia Armata
Editors: Alyssa Haag, Józia McGowan, DO, FACOI, FNAOME, CS
Illustrator: Jillian Dunbar
Copyeditor: Joy Mapes
What is face blindness?
Face blindness, also known as prosopagnosia, refers to a neurological disorder characterized by the inability to recognize familiar faces. When looking at a face, people with face blindness understand that they are viewing a face; however, they cannot identify individuals. Individuals with face blindness may have trouble identifying a family member or themselves. There are two types of impaired facial recognition: developmental, which is estimated to occur in as many as 1 in every 50 people, and acquired, which is quite rare.
Individual experiences of face blindness can vary. On the one hand, some people with face blindness cannot identify facial characteristics - they see only a blurred image of someone's face. This is called defective face processing, or apperceptive prosopagnosia. Others who have face blindness identify facial features with clarity, but they cannot associate the faces they see with familiar individuals, like friends, relatives, or famous people. This variety is known as associative prosopagnosia.
What causes face blindness?
The causes of face blindness differ depending on the type of face blindness. Developmental face blindness is a congenital disorder, in which individuals are born with an inability to develop face recognition skills despite having unimpaired vision and memory. While there is no presence of obvious brain lesions, several studies have revealed that these individuals may have anatomical differences in regions of the brain associated with face processing, like the fusiform gyrus area in the basal surface of the temporal and occipital lobe.
Developmental face blindness may have a genetic basis, as it commonly runs in families and can be present in multiple family members. However, the exact genes that control facial recognition have not yet been identified. Notably, monozygotic twins (i.e., identical twins) have similar face recognition skills, whereas dizygotic twins (i.e., fraternal twins), demonstrate different facial recognition abilities. Interestingly, developmental prosopagnosia appears to present more frequently in individuals with autism spectrum disorder, even though these conditions are independent of one another.Acquired face blindness, however, often results from severe brain injury to the temporal lobe, particularly the fusiform gyrus. Various types of brain injury -- including head trauma, inadequate blood supply to the brain (e.g., stroke), and inflammation of the brain (e.g., encephalitis) -- can suddenly cause problems with facial recognition. In addition, acquired face blindness can result from brain lesions, such as tumors. Finally, brain degenerating diseases, such as Alzheimer's disease, can also cause acquired face blindness, as they gradually reduce the size and abilities of parts of the brain.
What are the signs and symptoms of face blindness?
Prosopagnosia is thought to affect many aspects of life. In addition to being unable to recognize faces, individuals with face blindness may have trouble identifying facial expressions of emotion, like anger, surprise, or joy. For those who have face blindness, getting to know new people and forming relationships can be extremely difficult, and social struggles may lead to feeling isolated, lonely, or depressed. It is very common for individuals with face blindness to avoid social interaction and develop severe social anxiety, an overwhelming fear of interacting in social situations.
Moreover, face blindness also makes it challenging to keep track of each of the different characters in movies or television shows, so affected individuals may have trouble staying engaged, whether they are watching for their own entertainment or as a way to spend time with others.
Finally, people with face blindness often lose their ability to recognize objects or places they have visited before, so navigation can be a struggle as well.
How is face blindness diagnosed and treated?
Although formal diagnostic criteria does not exist for face blindness, diagnosis typically begins with an assessment of the individual’s history and a thorough physical examination. The examination typically involves a range of tests, such as the Cambridge Face Memory Test (CFMT). Individuals may be asked to memorize and later identify the faces of people they have never seen before. They may also be asked to identify famous characters, find similarities and differences between given faces, or estimate someone’s age and facial expression. Physical examination should always involve assessment of visual acuity, which measures the clarity and sharpness of one’s vision and memory, before confirming a diagnosis of face blindness. In cases of acquired prosopagnosia, further diagnostic testing may be needed in order to identify the underlying cause. Blood tests can evaluate the presence of inflammation, and imaging, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI), can reveal brain damage.
There are no specific medical interventions that have cured face blindness; therefore, treatment is aimed at improving recognition abilities. Many individuals with face blindness may learn adaptation techniques in order to help them identify their family and friends. These techniques may include trying to recognize others by remembering identifying features other than faces, such as their voices, the way they walk, or their hairstyles. This approach is not always successful, as small changes to these attributes may cause confusion, and the efficacy of adaptation techniques in general depends on the individual’s type of face blindness.
What are the most important facts to know about face blindness?
Face blindness, or prosopagnosia, refers to a neurological disorder characterized by the inability to recognize familiar faces. There are two types of face blindness: acquired and developmental. Acquired face blindness is the result of various pathologies that cause brain damage, whereas developmental, or congenital, prosopagnosia presents at birth and without any obvious brain lesions. Those unable to recognize faces often experience difficulties in their relationships, and they may also lack the ability to recognize places and objects. Thorough medical examination, including multiple tests of face recognition and an assessment of visual acuity and memory, can contribute to a diagnosis of face blindness. There are currently no curative medical interventions; however, some measures may help improve recognition abilities.
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Resources for research and reference
Corrow, S., Dalrymple, K., & Barton, J. (2016). Prosopagnosia: Current perspectives. Eye and Brain, 8: 165-175. DOI: 10.2147/EB.S92838
Diaz, A. (2008). Do I know you? A case study of prosopagnosia (face blindness). The Journal of School Nursing, 24(5): 284-289. DOI: 10.1177/1059840508322381
Kirshner, H. (2021). Agnosias. In J. Jankovic, J. Mazziotta, S. Pomeroy, & N. Newman (Eds.), Bradley and Daroff's Neurology in Clinical Practice (8th ed.). Elsevier.
National Institute of Neurological Disorders and Stroke (NINDS). (2019, March 27). Prosopagnosia information page. Retrieved February 22, 2021, from https://www.ninds.nih.gov/Disorders/All-Disorders/Prosopagnosia-information-page
Cook, R., & Biotti, F. (2016). Developmental prosopagnosia. Current Biology, 26(8): R312-R313. DOI: 10.1016/j.cub.2016.01.008