Aphasia: Cause, Types, Signs, and Therapy

Aphasia is a language disorder due to brain injury, typically in the left hemisphere, causing impairment in spoken and written language expression and comprehension. It can also result from neurodegenerative diseases, such as primary progressive aphasia. Aphasia is classified as nonfluent or fluent, with various subtypes based on differences in language skills. Recovery from aphasia varies depending on initial severity, lesion site, and factors such as poststroke depression and social isolation. As communication skills improve during recovery, clinicians should keep in mind that a person’s communication difficulties may not be neatly categorized into a single type of aphasia. Therefore, the classification may need to be revised accordingly.


Aphasia can be caused by various factors, but it is most commonly observed in individuals post-stroke, with approximately 25%-50% of all strokes resulting in aphasia. It is more common in older adults, and the incidence and prevalence of TBI and tumor-induced aphasia are not well-known. One study conservatively estimated that aphasia occurred in 1% of veteran soldiers of the Iraq and Afghanistan wars, while another study found that aphasia occurs in 13%-19% of individuals with TBI. A study estimated that the incidence of tumor-associated aphasia ranged from 30% to 50%, with an estimated prevalence rate of 198,028 to 330,048.

Signs and Symptoms

Aphasia symptoms can vary in severity depending on factors such as the extent of damage, the communication environment, and language background. Aphasia can cause deficits in verbal expression, auditory comprehension, reading, and writing. 

Anomia, or difficulty retrieving words, is common in all individuals with aphasia. Alexia (reading comprehension difficulties) and agraphia (written expression difficulties) may come with aphasia.

Aphasia can manifest in various signs and symptoms that affect spoken and written language. Common signs include:

Expressive language dysfunction

  • Difficulty retrieving words (anomia), jargon or generating meaningless phrases, neologisms or creating new words that are not recognizable, substituting sounds or words, omitting function words, making grammatical and syntax errors, and speaking haltingly. 

“Maria is a 6-year-old girl who has been experiencing difficulty expressing herself verbally. Her parents have noticed that she often struggles to retrieve words, especially when talking about things she has learned in school or with her friends. She sometimes uses incorrect words, such as saying “horse” when she means “zebra,” and has trouble combining words to form sentences that make sense. Maria’s speech is often halting and effortful, and she tends to use short, fragmented phrases. Her parents have also noticed that she makes grammatical errors, such as leaving out articles or using verb tenses incorrectly.”

Comprehensive language dysfunction

  • Signs include difficulty in spoken language comprehension, including understanding complex grammar, long or rapidly presented speech, and nonliteral language. 

“Sarah is a 7-year-old girl who has been diagnosed with receptive aphasia. She has difficulty understanding spoken language, especially complex sentences or instructions. When her mother tells her to clean up her room, Sarah might only hear the last part of the sentence and begin to clean up a toy instead of her entire room. When her teacher gives the class instructions, Sarah may need to hear them multiple times or have them broken down into smaller pieces to understand what she needs to do. She also struggles with understanding figurative language, such as idioms or metaphors, which can make social interactions more challenging for her.”


  • A written expression can be affected, leading to difficulty in writing, typing, or copying letters, words, and sentences, writing nonmeaningful syllables or words, and incorrect grammar or syntax.

Samantha is a 10-year-old girl who has been diagnosed with dyslexia and dysgraphia. She struggles with writing and spelling and often leaves out letters or writes them backward. When she writes sentences, they are often incomplete or have grammatical errors. She also has difficulty copying words and sentences accurately from the board in class, which affects her ability to keep up with her classmates. Samantha’s teachers have noticed that she has to work harder and take more time to complete written assignments, and her grades in written work are lower than her grades in oral work.” 


  • Reading comprehension can also be impaired, leading to difficulty recognizing words, sounding out words, and interpreting meaning.

“Samantha is a 10-year-old girl who has been diagnosed with alexia. She struggles with reading and comprehending written material of any length. Samantha may have difficulty recognizing common words, associating sounds with letters, and interpreting the meaning of written words. For example, when asked to read a simple sentence such as “The cat sat on the mat,” she may have difficulty recognizing the words “cat” and “mat” or may interpret the sentence as “The cat sat on the rat.” This can significantly impact Samantha’s academic performance and make it challenging for her to keep up with her peers in reading assignments and tests. Samantha may require specialized reading instruction, accommodations, and assistive technology to support her reading comprehension.”

Aphasia with Speech Problem

A speech disorder is a common symptom of aphasia and the types of aphasia that are most commonly associated with speech symptoms are:

  1. Broca’s aphasia: Also known as nonfluent or expressive aphasia, this type of aphasia results in difficulty with speech production, such as difficulty initiating speech, producing words and sentences, and forming grammatically correct sentences.
  2. Global aphasia: It is the most severe form of aphasia and involves significant difficulties with all aspects of language, including speech production, comprehension, reading, and writing.
  3. Mixed aphasia: This type of aphasia is a combination of Broca’s aphasia and Wernicke’s aphasia, which affects both speech production and comprehension.
  4. Transcortical motor aphasia: This type of aphasia is similar to Broca’s aphasia but is characterized by intact language comprehension despite difficulties with speech production.
  5. Anomic aphasia: This type of aphasia primarily affects word-finding abilities, making it difficult for individuals to retrieve words and express their thoughts clearly.

Other Common Types

There are other types of aphasia, each of which is characterized by specific language deficits. The most common types of aphasia include:

  1. Wernicke’s aphasia: Also known as fluent or receptive aphasia, this type of aphasia is characterized by fluent speech that is often devoid of meaning. Individuals with Wernicke’s aphasia may have trouble understanding spoken language and may use neologisms (made-up words) or replace words with inappropriate ones.
  2. Anomic aphasia: This type of aphasia is characterized by difficulty finding words, especially nouns. Individuals with anomic aphasia may be able to speak fluently and understand the language well but may struggle to retrieve the right words when speaking or writing.
  3. Conduction aphasia: This type of aphasia is characterized by difficulty repeating words or phrases, even though comprehension and spontaneous speech may be relatively intact.


Aphasia is caused by damage to the brain’s language network, which typically results from left-hemisphere damage. However, aphasia can rarely occur with a right-hemisphere lesion, especially in left-handed individuals who are more likely to have bilateral language networks or located in the right hemisphere. When a right-hemisphere lesion causes aphasia in a right-handed individual, it is called crossed aphasia. Common causes of aphasia include:

  1. Stroke: A stroke happens when the brain’s blood flow is disrupted, either by a blockage (ischemic stroke) or bleeding (hemorrhagic stroke). Ischemic stroke is more common and occurs when a blood clot blocks an arterial brain. Hemorrhagic stroke is less common and occurs when a blood vessel ruptures, causing bleeding in the brain.
  2. Traumatic Brain Injury: TBI occurs when the brain is damaged due to trauma such as a blow and penetrating injury to the head. TBI can result in damage to the language centers of the brain and lead to aphasia.
  3. Brain Tumors: Brain tumors are abnormal growths of cells in the brain. These tumors can be cancerous (malignant) or noncancerous (benign). A tumor (depending on its size and location) can cause aphasia by damaging the brain’s language centers.
  4. Brain Surgery: Surgery on the brain can be necessary to remove tumors, repair blood vessels, or address other issues. However, brain surgery can also damage the brain’s language centers, which can lead to aphasia.
  5. Brain Infections: Infections in the brain, such as meningitis or encephalitis, can cause inflammation and damage to the brain tissue. This damage can affect the brain’s language centers and lead to aphasia.

Role of Speech Therapists

Speech therapists are essential in screening, assessing, diagnosing, and treating people with aphasia. Their roles include clinical/educational services, prevention and advocacy, and education, administration, and research. Speech therapists have a variety of appropriate roles, such as assessing individuals who present with communication difficulties, diagnosing and documenting the presence of aphasia, and counseling people with aphasia and their care partners about communication and related issues. They can also provide prevention information to individuals who are at risk for conditions that cause aphasia and educate other professionals and the public about the needs of people with aphasia and the role of speech therapists in managing aphasia.

Speech therapists can develop person-centered treatment plans, provide treatment, and document progress in collaboration with the patient and the treatment team. They also serve as an integral collaborative team member, including physicians, other professionals, and the patient and their care partners. Additionally, Speech therapists help people communicate better as they recover from aphasia and stay up-to-date on the latest research to improve the understanding and treatment of aphasia.

The Code of Ethics for speech therapists requires them to limit their professional practice and competence to areas within their certification status, education, training, and experience.


Assessment is an important tool in identifying and diagnosing aphasia. Screening is a preliminary assessment to identify the need for further assessment, and it may be conducted using standardized or nonstandardized methods. A comprehensive assessment is conducted to identify the cause and characteristics of aphasia. It includes a case history, motor speech examination, language testing, and other evaluations to understand the person’s communication needs and the disorder’s impact on their life. 

Assessment tools may include standardized and nonstandardized tests, and clinicians should consider modifications and accommodations for factors such as hearing and visual impairments or cultural and linguistic differences. 

When assessing bilingual clients, clinicians should take into account when and how each language was learned, how each language was used before the condition, and which language is used more in daily activities. Documentation should include any modifications and accommodations made during the testing process to reconcile these factors.


Treatment for aphasia is personalized to target specific needs identified during assessment, with goals set by the person with aphasia and their caregivers. Person- and family-centered care is a team effort that values everyone’s knowledge, skills, and experiences. Community awareness of aphasia can be improved through clinicians providing education and outreach, partnering with people with aphasia to remove communication barriers to accessing communities, and developing aphasia-friendly resources. 

Expressive language treatments

Expressive language treatments are therapies designed to improve spoken language production in individuals with aphasia. There are various types of expressive language treatments, including:

  • Constraint-Induced Language Therapy (CILT) is a type of therapy that encourages communication by limiting other modes of communication.
  • Melodic Intonation Therapy (MIT) uses singing to help people with language difficulties. 
  • Phonological Components Analysis (PCA) focuses on sounds and their relationships.
  • Response Elaboration Training (RET) involves expanding on someone’s verbal communication.
  • Semantic Feature Analysis (SFA) encourages thinking about and discussing the features of a particular word.
  • Script Training focuses on teaching scripted conversation. 
  • Sentence Production Program for Aphasia (SPPA) uses a structured approach to improve sentence structure.
  • Treatment of Underlying Forms (TUF) focuses on teaching the grammatical structures needed for communication. 
  • Verb Network Strengthening Treatment (VNeST) focuses on improving the use and understanding of verbs.

Writing Treatment

Copy and Recall Treatment (CART) is a therapy that uses pictures or written words to teach spelling. If the patient spells correctly, they move on, but if they make a mistake, the clinician helps them practice by copying and recalling the word multiple times until they remember it.

Reading Treatments

  • Multiple Oral Re-Reading (MOR) is a technique where individuals with preserved letter-by-letter reading abilities, relatively intact comprehension and the ability to read aloud at the single-word level read a text passage aloud multiple times to improve whole-word oral reading. 
  • Oral Reading for Language in Aphasia involves repeated practice reading sentences aloud with the clinician to improve reading comprehension via phonological and semantic reading routes.
  • Supported Reading Comprehension approaches incorporate aphasia-friendly text supports and linguistic supports to improve reading comprehension.

Multimodal treatments 

Multimodal treatments use various modes of communication to aid individuals with language impairments. Examples include Augmentative and Alternative Communication (AAC), Gestural Facilitation of Naming, Promoting Aphasics’ Communicative Effectiveness, Reciprocal Scaffolding Treatment, and Visual Action Therapy (VAT).


Aphasia is a language disorder that affects spoken and written language comprehension and expression due to an injury to the brain or neurodegenerative disease. It can be classified into nonfluent or fluent types, and recovery depends on several factors. Aphasia symptoms include difficulty retrieving words, comprehension and writing difficulties, and reading comprehension difficulties. Stroke, traumatic brain injury, and tumors are common causes of aphasia. Treatment options may include speech therapy, occupational therapy, and augmentative and alternative communication strategies, but effectiveness may vary depending on the severity of aphasia and the individual’s engagement in therapy.

Written by: Dr. Jaafar Said

Edited and Reviewed by: Dr. Juhairah Magarang-Said