Agnosia is an uncommon medical condition that affects the nervous system, but it can cause significant problems in daily life. If you have the signs of agnosia, you should see your doctor for advice.
What is agnosia?
Agnosia is a rare type of neurological disorder (a condition that affects the nervous system). It is caused by damage to parts of the brain and, can either occur suddenly - for example, as a result of a stroke or an accident - or over time (such when a person has a brain tumour).
If you have agnosia, you will find it difficult or impossible to recognise objects, people, sounds or smells, even though your senses are working normally. For example, you may have nothing wrong with your vision, but because the parts of your brain that make sense of what you see are damaged, you won't recognise the objects you’re looking at.
Agnosia is not caused by memory loss, but it can be caused by dementia.
Types of agnosia
There are 3 main types of agnosia.
- visual agnosia (sometimes called visual amnesia) – being unable to recognise objects or people by sight
- auditory agnosia – being unable to recognise sounds
- tactile agnosia – being unable to recognise objects by touch
Within each of these types, there are different subtypes. For example, some people with visual agnosia have trouble recognising faces (known as face blindness) some have trouble recognising colours (known as colour agnosia); some have trouble recognising words (known as agnostic alexia); and others experience different effects on their vision.
It is also possible to have agnosia that affects your ability to recognise smells (known as olfactory agnosia) or taste (known as gustatory agnosia).
What are the symptoms of agnosia?
If you have agnosia, the symptoms will depend on what type of agnosia you have.
For example, if you have visual agnosia, you might have difficulty choosing between a knife and a fork, or identifying the right items of clothing when you get dressed. Or you might have trouble recognising familiar faces.
If you have auditory agnosia, you might be unable to recognise people’s voices, or recognise sounds as music, or name familiar sounds such as a phone ringing.
If you have tactile agnosia, you might be unable to recognise objects without using your sense of sight; for example, you may be unable to distinguish between a piece of metal and a piece of wood without looking at them.
How is agnosia diagnosed?
To diagnose agnosia, your doctor will probably:
- ask you questions about your symptoms and your general health
- ask you to identify some common objects using sight, touch, and smell
- check for other possible reasons for your symptoms (for example, by checking your hearing and vision)
- test your brain function and memory
- refer you for some imaging tests, such as a CT scan or MRI scan
How is agnosia treated?
Whether agnosia can be treated will depend on factors that include the type of agnosia, what has caused it, and the symptoms.
Since there is no cure for agnosia, where possible, doctors will try to find the underlying cause then treat that. For example, if a brain scan has shown that a tumour is growing, it might be possible to treat the tumour with radiation or surgery.
In some cases, a person might be able to learn strategies to help them cope. This usually involves learning how to use their other senses to compensate for an affected sense. For example, if you have auditory agnosia, learning how to lip read might be helpful.
Living with agnosia
If you have agnosia, it can cause significant problems in your daily life, as well as affect those around you. Here are some tips that might help you:
- Keep your environment as predictable as possible. For example, always keep things in the same place and ensure your living space is free of clutter.
- Stick to a familiar routine, and consistently do tasks the same way every time.
- Label things so you can identify what they are.
If you, or your family or carers, need help living with agnosia, you might find it useful to talk to your doctor or a counsellor. You can also find information and support online.
- Synapse – for people impacted by brain injury
- Stroke Foundation – for people affected by stroke
- Genetic and Rare Disease Network – for people with rare diseases
- National Institute of Neurological Disorders and Stroke (US)
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Last reviewed: June 2019