Understanding Agnosia: Causes, Types, and Treatment

Agnosia is a rare condition characterized by difficulties recognizing or perceiving familiar objects, people, or sounds due to sensory processing deficits. It primarily affects one’s ability to understand what they see, hear, or touch.

Generally, only one of the senses (vision, hearing, or touch) is affected. Therefore, individuals with agnosia are often able to utilize their other senses to compensate and improve their quality of life. However, there are also ways to improve one’s ability to process stimuli and regain affected functions.

To help you understand what agnosia is, this article will discuss its:

• Causes
• Types
• Treatment

Causes of Agnosia

Difficulties with recognition in individuals with agnosia are unrelated to memory, attention, or other cognitive problems. Instead, agnosia is caused by damage to the areas of the brain responsible for sensory processing, such as the posterior cortex and occipitotemporal regions.

Agnosia can develop following various neurological conditions, including:

• Stroke
• Tumor
• Infection
• Dementia
• Hypoxia
• Toxins
• Head injury
• Developmental disorders

Although agnosia affects one’s ability to recognize or perceive sensory information, the senses themselves function normally. For example, individuals who cannot recognize what they see are not experiencing a problem with their eyes. Rather, they’re experiencing a problem with the way the brain processes what their eyes see.  

Depending on which areas of the brain are affected, individuals may experience a wide variety of symptoms. In the following section, we’ll differentiate the various types of agnosia.

Types of Agnosia

Agnosia affects the way the brain processes what you see, hear, or touch, but it generally only affects the processing of one of these senses.

Below, we’ll discuss the differences between visual, auditory, and tactile agnosias.

Visual Agnosia

Visual agnosia refers to difficulties recognizing what you see despite being able to see clearly. For some, certain types of objects may be more difficult to recognize than others.

Visual agnosias are the most common and best-understood type of agnosias. They can be further classified as apperceptive or associative.

Apperceptive agnosia refers to impairments caused in the early stages of visual processing when the brain gathers visual stimuli into an image. Individuals with this classification of agnosia may struggle to match two identical objects; however, they are often able to verbally identify how the objects appear (the color, texture, etc).  

In contrast, associative agnosia describes the inability to assign meaning to images. Individuals with this type of agnosia can often draw, match, or copy what they see; however, they struggle to match different categories or presentations of a stimulus. For example, they may not be able to match a mechanical pencil to a wood pencil, or a closed umbrella to an open one. Additionally, individuals with associative agnosia struggle to name the objects they are looking at.

Types of visual agnosias include:

• Prosopagnosia describes difficulties recognizing familiar faces. However, individuals are usually still able to identify other aspects of a person such as their gender, hair, and clothing.
• Simultanagnosia describes difficulties seeing more than one object at a time when they are grouped together.
• Color agnosia describes difficulties distinguishing between colors.
• Topographical agnosia describes difficulties interpreting spatial information, resulting in difficulties with navigation using visual cues.
• Finger agnosia describes difficulties differentiating between fingers.
• Akinetopsia describes the difficulties perceiving motion. Most people with this condition see moving objects as a series of stills.
• Agnostic alexia describes difficulties recognizing written words visually despite being able to write and talk.

Auditory Agnosia

When an individual has auditory agnosia, they are unable to recognize or perceive what they hear. Although their hearing functions are normal, the brain struggles to assign meaning to or differentiate between sounds.  

Types of auditory agnosias include:

• Phonagnosia describes difficulties recognizing familiar voices.
• Verbal auditory agnosia (pure word deafness) describes difficulties understanding spoken words. However, these individuals can typically read, write, and speak properly, which is what distinguishes it from some types of aphasia.
• Nonverbal auditory agnosia describes difficulties comprehending nonverbal sounds. For example, when they hear a car motor start, they would not associate it with an engine or car. However, they are still able to understand spoken language.
• Amusia describes the inability to differentiate music from other types of sounds.

Tactile Agnosia

Tactile agnosia refers to the inability to recognize or perceive touch. Individuals with tactile agnosia can feel what they touch; however, they often struggle to identify or differentiate what they are touching.

Types of tactile agnosias include:

• Amorphognosia describes difficulties identifying the size and shape of an object by touch. For example, you could not tell if an object is round or square just by feeling it.
• Ahylognosia describes difficulties identifying distinctive physical properties of an object such as texture and weight.

Now that you understand the various ways agnosia can present itself following a neurological injury, the following section will discuss management interventions and treatment.

Agnosia Treatment

Agnosia treatment involves identifying sensory processing deficits and implementing effective ways to optimize the individual’s functional independence despite them. Additionally, it can involve repetitively practicing targeted exercises and activities to improve the individual’s ability to process sensory information.

A major obstacle in treating agnosia is getting the individual to acknowledge they have it. Anosognosia refers to the state of unawareness that deficits exist. As a result, individuals with anosognosia are often resistant to participating in any form of treatment, as they lack the insight needed to recognize that they have a problem.

An effective way to get an individual to acknowledge that they have agnosia is to repetitively ask them to identify or differentiate people or objects using the affected sense. Then, have the individual identify or differentiate the same stimuli using one of their unaffected senses. They should gradually become aware of their sensory processing deficits and acknowledge the need for treatment.

Compensatory Strategies

Treatment for agnosia involves learning how to use compensatory strategies to help make up for sensory processing deficits. Because agnosia generally only affects one of the senses, individuals can learn how to recognize people, objects, or places using their other, unaffected senses.

Examples of compensatory strategies include:

• feeling an object if you have difficulties recognizing what it is by sight
• identifying a person by their voice if you have difficulties recognizing their face
• learning to use lip-reading if you have difficulties auditorily comprehending what someone is saying

By utilizing alternative cues and combining sensory modalities, individuals can improve their ability to recognize or perceive familiar objects, people, and sounds.

Rehabilitation

For individuals with less severe agnosia, treatment also focuses on rehabilitation. Individuals with agnosia are often capable of improving their deficits through intensive, task-specific practice. This is possible because the brain has neuroplasticity, which is the ability to make adaptive changes in its neural circuitry. It allows for functions affected by damage to be rewired to unaffected regions of the brain and improved through repetitive practice.

Rehabilitation approaches must be individualized and focus on the client’s specific sensory deficits. Participating in speech and occupational therapy can help individuals with agnosia identify their specific sensory deficits and practice targeted exercises and activities to stimulate the brain and improve them.

Understand Agnosia: Key Points

Agnosia is a neurological disorder characterized by difficulties recognizing or perceiving visual, auditory, or tactile stimuli. It’s caused by damage to the areas of the brain responsible for processing sensory information.

Generally, only one of the senses is affected, and individuals can learn to rely on their other senses to make up for deficits and improve their quality of life. Additionally, individuals can practice targeted exercises and activities to promote neuroadaptive changes in the brain and improve sensory processing skills.

We hope this article helped you understand what agnosia is, the various ways it can present itself, and how to optimize your quality of life if you have it.