What causesprosopagnosia?

There are two types of prosopagnosia known as:

• developmental prosopagnosia where a person has prosopagnosia without havingbrain damage
• acquired prosopagnosiawhere a person develops prosopagnosia after sustaining damage to their brain, often following a stroke or a head injury

In the past, most cases of prosopagnosia were thought to occur following a brain injury (acquiredprosopagnosia).But research has found that many more people haveprosopagnosia without having brain damage (developmentalprosopagnosia) than was first thought.

Developmental prosopagnosia

A number of studies have indicated that as many as one in 50 people may have developmentalprosopagnosia, which equates to about 1.5 million people in the UK.

Mostpeople withdevelopmentalprosopagnosia simply fail to develop the ability to recognise faces. Someone born with the condition may not realise they have a problem.

Developmental prosopagnosia may have a genetic component and run in families. Many people with the condition have reported at least one first-degree relative, such as a parent or sibling (brother or sister) who also has problems recognising faces.

Acquired prosopagnosia

Acquiredprosopagnosia is rare. When someone acquires prosopagnosia after a brain injury, they'll quickly notice that they've lost the ability to recognise people they know.

But if prosopagnosia occurs after brain damage in early childhood, before the child hasfully developed the ability to recognise faces, they maygrow up notrealising they're unable to recognise faces as well as other people can.

Prosopagnosia isn't related to memory problems , vision loss or learning disabilities , butit'ssometimes associated with other developmental disorders, such as autistic spectrum disorder , Turner syndrome and Williams syndrome.