Agnosia: definition, causes, treatment
Image by stefamerpik on Freepik

Agnosia is the inability to recognize an object, sound, smell, or face through the senses, without damaging sensory abilities.

An agnosic person has completely normal sensory functions but has difficulty memorizing or interpreting objects.

In most cases, agnosia is associated with a neurological disease or brain injury. Agnosia can involve different senses including sight (visual agnosia), hearing (auditory agnosia), or touch (tactile agnosia). Let’s take stock together about this disorder, its causes, and its treatments.

Agnosia: definition

Agnosia is a gnosic disorder, that is, a disorder of recognition. An agnosic person cannot recognize an object, a sound, a smell, or a known face.

Agnosia is distinguished from other Gnosic disorders by the absence of primary sensory deficit: an agnosic person has normal sensory functions.

The origin of agnosic disorders is closely related to the transmission or interpretation of sensory information. In the brain, impaired sensory memory can explain the onset of certain agnosic disorders.

Agnosic disorders usually involve only one sense. The most common forms are visual, auditory, and tactile agnosia.

Visual agnosia

Visual agnosia is when a person is unable to recognize certain objects, shapes, or familiar signs by sight. However, visual agnosia should not be confused with a vision disorder, which is characterized by a decrease in visual acuity.

Depending on the case, visual agnosia may be related to a problem in the interpretation of information concerning space, shapes, faces, or colors. There are several forms of visual agnosia.

  • Object agnosia: it is either associated with associative agnosia with an inability to name an object present in the visual field, or with aperceptual agnosia with an inability to name and draw an object present in the visual field.
  • Prosopagnosia: this is the inability to recognize familiar faces, both those of close people and one’s own face.
  • Color agnosia: This agnosia is characterized by an inability to name different colors.

Auditory agnosia

Auditory agnosia results in the inability to recognize certain known sounds. Depending on the case, it is possible to distinguish:

  • cortical deafness, characterized by an inability to recognize known sounds, familiar noises, or music;
  • verbal deafness, which corresponds to an inability to understand spoken language;
  • amusia, which refers to an inability to identify melodies, rhythms, and timbres of voices.

Tactile agnosia

The sense of touch comes into play here. Also called astereognosis, tactile agnosia is characterized by an inability to recognize an object by simple palpation. This recognition disorder can concern the material, weight, volume, or shape of the object.


Asomatognosia is a particular form of agnosia. It is characterized by a loss of recognition of part or all of one’s own body.

The agnosic person here has the feeling that some parts of his body do not belong to him. There are two forms of asomatognosia:

  • autotopoagnosia, which is characterized by an inability to recognize different parts of the body;
  • Digital agnosia that concerns only the fingers.

The causes of agnosia?

Agnosic disorders can have different explanations. They are often due to the appearance of brain damage as a result of:

  • a stroke or stroke, which is caused by a blood circulation disorder in the brain;
  • head trauma, a shock to the skull that can cause brain injury;
  • neurological disorders, including dementia or neurodegenerative diseases such as Alzheimer’s disease;
  • a brain tumor that results in the development and multiplication of abnormal cells in the brain;
  • a brain abscess, or brain abscess, which can be the result of different infections.

The consequences of agnosia?

Agnosic disorders cause discomfort in daily life that can be more or less important depending on the case. But depending on the severity, they can affect cognitive functioning and lead to behavioral disorders.

However, the consequences and evolution of agnosia depend on several factors such as:

  • the type of agnosia;
  • the cause of the symptom;
  • the patient’s condition.

Treatment: how to treat agnosic disorders?

To treat agnosia effectively, the cause must first be treated. Everything here depends on the diagnosis. This is usually performed by clinical examination and supplemented by thorough medical examinations. Neuropsychological examinations and medical brain imaging tests are sometimes necessary to confirm the diagnosis.

Treatment of agnosia is usually accompanied by rehabilitation to improve the patient’s quality of life. This rehabilitation can involve different specialists including occupational therapists, speech therapists, and physiotherapists.

Image Credit: Image by stefamerpik on Freepik

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