Prosopagnosia (face blindness): Causes, symptoms and management

What Is Prosopagnosia?

Prosopagnosia is a condition that makes it difficult, or impossible, for people to recognize faces — even of people close to them. Although vision itself isn’t affected, the part of the brain that processes this information can’t do it correctly. This condition is also known as face blindness. 

Prosopagnosia is one of several different types of agnosia. An agnosia is a neurological disorder where your brain can’t understand information from your senses. It usually only affects one sense at a time. The sense itself functions normally, but your brain can’t process or recognize the information it’s detecting. 

The term prosopagnosia comes from the Greek words for “face” (prosopon) and “lack of knowledge” (agnosia). The term was coined by a scientist named Joachim Bodamer. Although this term was coined in 1947, reports of face blindness have happened throughout history. 

SEE RELATED: Visual agnosia: Symptoms, types and causes 

Symptoms and diagnosis

Specific symptoms will depend on the type of prosopagnosia. Diagnosis can be difficult because there is no proven test or method. Doctors typically use tests that rely on cognitive neuroscience and imaging.

Symptoms

Prosopagnosia is divided first by when it begins: developmental (congenital) prosopagnosia is present from early life, while acquired prosopagnosia follows brain injury or disease. 

There are two primary types of prosopagnosia: apperceptive and associative. 

In apperceptive prosopagnosia, visual perception of faces is difficult. This also makes it harder to see facial expressions or other nonverbal cues.

In associative prosopagnosia, you may be able to perceive a face but not remember it. This makes it hard to recognize people at all, even people you know or are close to. 

The two different types may be related to damage in specific regions of the brain, specifically the face-processing network. 

People with prosopagnosia may also struggle to: 

• Identify their own face 
• Discern between faces and objects 

SEE ALSO: Signs that may show your child has a vision problem

Social impact of prosopagnosia

In many cases, not being able to identify faces can cause anxiety or fear of social situations. This has been linked to:

• Negative effects on mental health 
• Depression
• Anxiety
• Mood disorders

The evidence though is mixed and comes largely from self-report. A study from 2024 found no significant link between measured face-recognition ability and psychological well-being, and only a weak association between self-reported difficulty and social interaction anxiety. Face blindness does not always lead to these problems in everyone who has it.

Children with face blindness may struggle with: 

• Social development
• Separation anxiety
• Behavioral problems

Diagnosing prosopagnosia

There is a range of tests your doctor may use to diagnose face blindness. Your brain may be examined with the use of imaging tests, which may include: 

• Computerized tomography (CT) – CT provides images of the brain using X-ray data modeled on a computer. It is often used to identify internal injuries or tumors. 
• Magnetic resonance imaging (MRI) – MRI uses your body’s response to a magnetic field to produce images. It is often used to examine the soft tissue parts of the body (not bone). 
• Evoked potentials – Evoked potential testing uses electrodes to measure your brain’s response to a stimulus. This test is used to see how fast nerve responses reach your brain. This can help determine damage, even if it’s subtle. 

There will likely also be tests of your senses, memory, and ability to recognize faces and objects. The diagnostic criteria for apperceptive and associative prosopagnosia can be different. There are several different tests that focus on different aspects of recognition and memory such as:

• Cambridge Face Memory Test (CFMT) – Measures the ability to learn and then recognize unfamiliar faces.
• Cambridge Face Perception Test (CFPT) – Measures the ability to tell faces apart.
•  Famous Faces Test (FFT) – Measures recognition of well-known people.
•  20-Item Prosopagnosia Index (PI20) – A questionnaire about everyday difficulties recognizing people.

Your doctor may ask questions relating to: 

• Whether you’ve experienced head trauma
• Whether you have any other underlying conditions, like stroke or Alzheimer’s disease

Causes and Risk Factors

There are several different brain regions that can be affected in prosopagnosia. Damage or developmental problems in any of these areas may cause face blindness. The condition can be congenital (at birth) or acquired (developed later in life). 

Causes of congenital prosopagnosia

Some people are born with prosopagnosia. It’s possible there is a genetic component to this condition. Sometimes it runs in families, implying it could be inherited. For instance, mutation of a gene called MCTP2 is sometimes found in face blindness. This gene is thought to be involved in producing a calcium-binding protein found in the brain.  

However, there are many genes that could be involved. Mutations may also occur de novo, meaning they’re new, spontaneous changes. 

SEE ALSO: How DNA testing can detect eye diseases

Causes of acquired prosopagnosia

Prosopagnosia can also be acquired. This often happens because of a brain injury.

The perception of faces involves a network of connected regions in your brain. The temporal lobe is the area of the brain that helps you understand sensory information and connect to memories. It contains a part called the fusiform gyrus. The fusiform gyrus helps connect the part of your brain that houses memories to the part that processes vision. 

Inside the fusiform gyrus is another area called the fusiform face area. This part in particular is linked to recognizing and remembering faces. It does not however work alone. Face recognition runs on a small network where the occipital face area handles a face's basic visual features, the fusiform face area processes identity, and a region in the superior temporal sulcus tracks information like expression and gaze. Regions further forward in the temporal lobe link a face to what you know about the person.

An injury to these or other areas of the brain could cause prosopagnosia. These injuries can be caused by several different events or conditions, which may include: 

• Head injuries 
• Alzheimer’s disease or dementia 
• Brain tumors 
• Stroke 

Risk factors

Parents can pass down congenital prosopagnosia, which is thought to be autosomal dominant. This means you only have to inherit one copy of the mutated gene to get the condition. Having a family member with congenital prosopagnosia means someone may be more likely to inherit it. Most cases, though, have no identified genetic cause, and researchers believe many genes are likely involved. 

But other causes, like injuries, are hard to predict. You can’t always protect against them. But there are ways you can reduce your risk. These may include: 

• Protecting against any heart or circulatory conditions with attention given to blood pressure, cholesterol, blood sugar and smoking alongside a balanced, healthy diet 
• Wearing safety equipment when applicable to avoid head injuries
• Managing any chronic health conditions that run the risk of causing brain damage over time (like epilepsy or sleep apnea) 
• Getting timely treatment for infections before they can spread to the brain 

Living with prosopagnosia

There are some practical steps you can take to help with prosopagnosia, like: 

• Telling people about your prosopagnosia when you first meet
• Using name tags or other labels (like where people sit at work) 
• Asking people to introduce themselves 
• Asking close friends or colleagues for help identifying people 

Your healthcare provider can also help by referring you to specialists, programs and other resources. This includes mental health therapy or counseling resources for problems like anxiety and depression.

Support networks and resources

There are also several face blindness organizations that connect people with prosopagnosia to each other for support. Some organizations may also offer specialist resources, presentations or modules. 

Treatment and management

Treating the underlying condition or injury could help the prosopagnosia resolve. However, this depends on condition severity, the treatment used and other factors. This could take anywhere from a few months to a full year. 

However, a majority of cases of prosopagnosia are permanent. For these cases, it will be important to follow recommendations from your healthcare professional. They can help you find ways to manage your condition so its impact is minimal. 

For instance, perceptual training can help apperceptive prosopagnosia. This training helps you learn how to identify facial features, expressions and cues. Rehabilitation that focuses on coping can help you learn alternative ways to recognize someone (like using voices, shapes and context clues).

Emerging therapies 

Wearable devices that can help with visual impairment have shown a possible benefit in patients with brain injuries. For prosopagnosia, a new wearable system was tested and showed positive results. The system had real-time face recognition software and a training mode to help the wearer improve their recognition abilities over time. 

Oxytocin might also be a promising treatment. Oxytocin is a chemical in your brain involved in social functions. One study showed that administering oxytocin using an intranasal spray gave participants better scores on a face recognition test. 

Non-invasive brain stimulation (stimulating a certain area of the brain with an electrical current) may also help prosopagnosia. This intervention has shown positive results in cognitive training tasks, like perceptual training and motor skills.

Frequently asked questions about prosopagnosia

Prosopagnosia affects everyone differently, and it can come with a lot of questions. 

How to pronounce prosopagnosia

Prosopagnosia is pronounced “pro-so-pag-no-zee-ah.”

Can prosopagnosia be cured? 

Prosopagnosia itself cannot be cured. A majority of cases are permanent. However, sometimes the cause of acquired prosopagnosia can be cured. In these cases, it is possible for the prosopagnosia to resolve. 

What do people with prosopagnosia see? 

Prosopagnosia affects everyone differently. Some people may be able to see faces, but those faces may all look the same. Others may see a blurry image instead of someone’s face (this usually happens with the apperceptive type). 

How common is prosopagnosia? 

There isn’t a lot of data on how common acquired prosopagnosia is. This is partly because the diagnostic criteria for prosopagnosia versus a poor ability to recognize faces aren’t easy to define. Developmental (congenital) prosopagnosia is widely reported to affect about 2% to 2.5% of people. A 2023 study tested more than 3,000 adults and applied the different diagnostic cutoffs researchers have used over the past 14 years. Depending on which cutoff was used, the estimated prevalence ranged from less than 1% to more than 5%. The cutoffs most commonly used in research produced a figure closer to 1%.  

One study suggests that diagnostic criteria should be expanded to be more inclusive, which could lead to new diagnoses among millions who may have the disorder but don’t realize it.  

How is the still-face paradigm different from developmental prosopagnosia?

The still-face paradigm is a method that has been used in mother-baby studies. It involves the mother adopting a still face instead of engaging with the baby. The children usually react negatively, doing their best to re-engage their mother. 

Some people with prosopagnosia may have a difficult time seeing the emotions on people’s faces. This can make it harder to form relationships, and may negatively affect mental health. However, there is no recognized connection between the still-face paradigm and developmental prosopagnosia. 

SEE RELATED: How important is eye contact to a child’s development?

Raising awareness about prosopagnosia

Prosopagnosia might be more common than people think, especially because it can be hard to differentiate it from a general difficulty with faces. 

Alone, it isn’t dangerous for your health. However, face blindness could indicate a neurological disorder, brain tumor or other serious condition. 

A sudden loss of the ability to recognize faces is a medical emergency when it appears alongside signs of a stroke. Call 911 immediately and do not drive yourself if your suddenly not recognizing faces happens together with any of the following:

• Weakness or numbness on one side of the body
• Drooping on one side of the face
• Slurred speech or trouble finding words
•  A sudden, severe headache unlike any you’ve had before
• Sudden loss of vision, double vision or loss of part of your field of view

If the change came on suddenly but you have none of these signs, contact your healthcare provider promptly rather than waiting. 

If you do have prosopagnosia, there are ways to possibly help you see and remember faces. Your healthcare provider can recommend treatment strategies and suggest organizations that support people with this condition.