Agnosia

Agnosia is a rare disorder that makes you lose the ability to recognize objects, faces, voices, or places previously known. It is specific for a given sensory modality. 

There are three main types of agnosia: 

• Visual: This is the most common type of agnosia, in which you are not able to recognize objects or faces. It includes:
  

  • Prosopagnosia, that is, the inability to identify faces even though the person is known 

  • Agnostic Alexia, that is, the inability to recognize written pieces (including letters and words)

  • Colour Agnosia, that is, the inability to discriminate between colours and therefore cannot name the colour

  • Object Agnosia, that is, the inability to name objects

  • Simultanagnosia, that is, the inability to recognize a whole image although individual details are recognized

• Auditory: People with auditory agnosia are unable to recognize sounds and language to varying degrees, depending on the severity of the disease. It includes:
  

  • Auditory/verbal information agnosia, that is, the inability to hear words

  • Auditory agnosia, that is, the inability to hear environmental sounds such as a car starting or a dog barking

  • Receptive amu​sia, that is, the inability to hear music

• Tactile: This type of agnosia is the inability to identify objects by touch.
  

Agnosia can result from: 

• Strokes 
  

• Brain injury 
  

• Dementia
  

• Tumour
  

• Developmental disorders
  

• Overexposure to environmental toxins
  

• Other neurological conditions

When to seek expert advise

If you or a loved one is facing similar symptoms, it is recommended that you consult with your doctor immediately. You can obtain additional information and expert medical advice from the Section of Neurology at The Aga Khan University Hospital.