Agnosia: Definition, Causes, Symptoms, Types and Treatment

It is the loss of the ability to recognize objects, faces, voices or places.

It’s a weird mess. If you have this condition, you can still think, talk and interact with the world. Agnosia generally affects only a single information pathway in the brain.


Agnosia occurs when the brain suffers damage along certain pathways. These routes connect the main areas of sensory processing. These parts of the brain store knowledge and information. Primary areas of sensory processing include visual and auditory cortices.

It is usually caused by lesions in the parietal and temporal lobes of the brain. These lobes store information and semantic language. Strokes, head trauma or encephalitis can cause injuries.

Other conditions that damage or deteriorate the brain can also cause agnosia. These conditions include:

  • Dementia.
  • Poisoning by carbon monoxide.
  • Anoxia.

Types and symptoms of agnosia

There are 3 different types of agnosia.

  • Visual.
  • Auditory.
  • Tactile.

Agnosia visual

Visual agnosia occurs when there is brain damage along the pathways that connect the occipital lobe of the brain to the parietal and temporal lobes. The occipital lobe gathers incoming visual information. The parietal and temporal lobes allow you to understand the meaning of this information.

Apperceptive visual agnosia

Visual apperceptive agnosia causes difficulty in assembling parts of an image into a comprehensible whole. This condition can make it difficult for him to understand the relationship between the objects.

You can, for example, try to copy an image of a circle and end up drawing a series of concentric scribbles.

You can still use vision to navigate your environment and pick up objects without problems. Visual apperceptive agnosia is usually caused by lesions in the parietal or temporal lobes on both sides of the brain.

Associative visual agnosia

Associative visual agnosia is the inability to remember information associated with an object. This can include the name, use or origin of an object. This form of agnosia does not prevent you from drawing an object.

You may not be able to name the object in the drawing. You can recognize and use an object that is shown to you, but you may not be able to tell what the object’s name is.


Prosopagnosia is the inability to recognize faces. It is caused by problems with the fusiform face area (FFA), a specific region of the brain that recognizes faces. The difficulty with facial recognition can also occur in Alzheimer’s disease. It happens because brain deterioration damages this region.

Autism can also cause difficulty in recognizing faces. A 2014 article discussed how children with autism spectrum disorders can learn to recognize faces in a different way. It may be harder for them to understand the identity or emotional state of another person.


Achromatopsia is the loss of color vision due to lesions in the V4 region of the brain. It is the inability to name colors despite being able to perceive them. Color anomia occurs when an injury separates the V4 regions of the brain from the language areas.

Alexia pure

It is the inability to recognize words visually. It is not possible to read with pure alexia. In general, you can still speak and write without difficulty.


The akinetopsia is the inability to perceive movement. This condition can cause you to see moving objects as a series of still images, such as an object moving under a strobe light. If the condition is severe, you may not be able to see any movement.

Agnosia auditiva

Auditory agnosia is also known as deafness of pure words. It is the inability to recognize or process sounds despite intact hearing. It develops when the A1 sound processing region of the brain is disconnected from its language centers. He can still read, write and speak with deafness of pure words.


Phonagnosia is the inability to recognize and identify familiar voices. It develops when the brain suffers damage to a certain part of the sound association region.

This region is located in the right half of the brain. You can still understand the words that others speak if you have this condition. It can also recognize environmental sounds or sounds produced by objects.

Tactile agnosia

Tactile agnosia is the inability to recognize objects through touch. You can feel the weight of the object. However, you may not be able to understand the meaning or use of the object. Lesions in the parietal lobe of the brain are the cause of tactile agnosia.


Astereognosis is the inability to identify objects only by touch. This condition does not allow you to associate information about size, weight and texture with the correct words. You can still name objects by sight. You can also draw images of objects, as well as reach them.


Autotopagnosia is when you lose the ability to orient the parts of your own body. Damage to the left parietal lobe of the brain causes this condition.

You know where your limbs are in space at all times, even with your eyes closed. But this consciousness is distorted when the internal representation of the brain of the brain is damaged.


The treatment of the underlying cause and the care of the symptoms is the main way to treat agnosia. The main objective is to allow him to function independently in his daily life.