What Causes Difficulty with Talking in Adults?

As people age, certain conditions can cause them to have speech problems, struggle to communicate, or stop speaking altogether. While this can feel overwhelming, education is power. Learning about your or your loved one’s diagnosis can help you understand the right next steps, which may include speech therapy. 

This article explains common diagnoses that can cause speech issues in adults and when speech therapy can be helpful.


Our brains have two halves: the left side and the right side. Our language skills typically are developed on the left side. When areas of this side of the brain are damaged, such as by a stroke, it can lead to an impairment of language abilities.

Aphasia is a language disorder that occurs as a result of this damage. Aphasia can make it difficult for a person to speak, understand, read, and write. The severity of aphasia can range dramatically. In some people, communication can be almost impossible. In other people, the effects are quite minor.

How does aphasia affect language?

Aphasia can disrupt only a single aspect of language, such as the ability to recall people’s names or string words together in clear sentences. However, more commonly, multiple parts of communication are involved. This can make it difficult for people to communicate with loved ones, navigate activities of daily living, socially connect with others, or perform at work.

It’s important to know that people with aphasia are not any less intelligent than they were before. While they may have a hard time expressing their thoughts and ideas, the thoughts and ideas themselves are not disrupted. People with aphasia simply need help to communicate clearly.

What causes aphasia?

As mentioned, aphasia is often the result of a stroke. About 25% to 40% of stroke survivors acquire aphasia. However, aphasia can be caused by any type of brain damage, including brain tumors, head injuries, brain disorders, or other neurological disorders like Alzheimer’s disease.

What are the signs of aphasia?

Some symptoms of aphasia include:

  • Difficulty thinking of the right words to say

  • Using the wrong words in sentences or leaving out words altogether

  • Saying related but incorrect words, such as “steak” instead of “hamburger”

  • Switching the order of words, such as “bean green” instead of “green bean”

  • Using made-up words

  • Not using full and complete sentences

  • Not understanding what others are saying; this can be worsened if someone is speaking quickly, using longer sentences, or located in a noisy environment

  • Difficulty reading

  • Trouble spelling and writing sentences


Dysarthria is a motor-speech disorder that can cause speech problems in adults. Dysarthria weakens the muscles used to form words and produce speech. This makes it difficult to coordinate and control these muscles, which can lead to a range of communication challenges. Dysarthria is often the result of damage to parts of the brain that are responsible for these muscles' movements. 

How does dysarthria affect speech?

This disorder can affect many aspects of an adult’s speech. For example, a person’s speech may become slow, mumbled, or slurred. They may lose the ability to pronounce sounds and words correctly. They may be unable to control the volume of their voice or the quality and pace at which they talk. Finally, because dysarthria involves muscle weakness, some individuals may drool when speaking or have breathing issues. 

What causes dysarthria?

Dysarthria is often caused by damage to the brain and, in particular, to specific areas of the brain that are important for the motor aspects of speech. 

While dysarthria can occur at birth (referred to as congenital dysarthria), it is often a result of an illness or injury. Some common causes of dysarthria include: 

  • Stroke

  • Brain injury

  • Tumors

  • Parkinson's disease

  • Amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease)

  • Huntington's disease

  • Multiple sclerosis

  • Cerebral palsy

  • Muscular dystrophy

In addition to brain damage, dysarthria can be caused by damage to the organs involved in speech production. For example, someone who’s received surgery to their head, tongue, or voice box may develop dysarthria, as well as someone who has experienced trauma to their face or mouth.

Dysarthria can affect your speech patterns in many different ways, depending on its cause. Some people with dysarthria may only have minor speech problems that still allow them to have everyday conversations without trouble. Others have more severe symptoms that make it difficult for other people to understand their speech at all. 

What are the signs of dysarthria?

Typical symptoms of dysarthria that affect speech include: 

  • Changes to the speed at which you talk; you may talk rapidly or very slowly

  • Speech that sounds slurred, mumbled, or choppy

  • Abnormal or varied rhythm in your speech

  • Difficulty controlling the volume of your voice

  • Difficulty controlling and moving your lips, jaw, and tongue

  • A nasal or hoarse voice quality

Parkinson’s disease

Parkinson’s disease, also called PD, is a neurodegenerative disorder affecting movement. The cause of Parkinson’s is not known, but scientists suspect environmental factors or genetics may play a role. Its symptoms usually begin gradually and worsen over time.

The signs of Parkinson’s include:

  • Tremor (or trembling) in the hands, arms, legs, jaw, or head

  • Rigid muscles anywhere on the body, which limits one’s range of motion

  • Impaired posture, balance, and coordination

  • Slowed movement (also known as bradykinesia)

  • Difficulty swallowing, chewing, and speaking

  • Cognitive changes such as problems with attention, planning, language, and memory

  • Sleep disorders

  • Depression or other emotional changes

How does Parkinson’s cause speech issues?

Some of the motor symptoms of Parkinson’s, such as limited facial expressions, overall slowed movement, and stooped posture, make it difficult for the person to speak clearly and loudly enough to be understood by others. People with Parkinson's often speak very quietly and in a monotone-sounding voice, so it can be tough to convey much emotion. They may sound breathy or hoarse, or they may slur their words and mumble. Many people with Parkinson's speak very slowly.

The cognitive impairments connected to Parkinson's also affect clear speech–for example, struggling to find the right words. Many people with Parkinson's have reported that these challenges make it extremely difficult to talk with family, friends, and coworkers. They often decide to limit social interactions because of this.

Dementia or Alzheimer’s disease

Dementia is a disease that causes memory loss, as well as a loss of language, communication abilities, and problem-solving skills. It is a progressive disease, which means it gets worse over time. 

Alzheimer’s is the most common type of dementia, making up about 60% to 80% of diagnosed dementia cases. It is caused by damage to the nerve cells of the brain during aging.

Some signs of dementia related to language and cognitive-communication include:

  • Memory changes big enough to make daily life more difficult 

  • Problems with word-finding and expressing thoughts clearly

  • Difficulty understanding other people when talking with them

  • Becoming disoriented; not knowing where you are or what time it is

  • Impaired judgment and difficulty problem-solving

As the disease progresses, it is likely that the person will continue to lose communication abilities. Toward the final stages, they could lose the ability to speak. 

How speech therapy helps adults who have difficulty talking

Speech and language problems can have a major impact on an adult’s life. We communicate every day, for a variety of reasons–from telling someone that you’re cold or tired, to expressing love or concern, to sharing ideas or making a request. So communication challenges can be frustrating and isolating. They can affect a person’s independence, mental health, relationships, and overall quality of life.

A speech therapist can provide support, show the person techniques for clearer communication, and teach caregivers how to help them at home. 

This is why speech therapy is so important for anyone with these diagnoses. Speech therapists can provide support and show the person techniques and strategies to use for clearer communication. They also teach caregivers how to help and interact with their loved one at home. 

Speech therapy benefits adults with aphasia, dysarthria, Parkinson’s, dementia, or other conditions that affect communication, such as acquired apraxia of speech. A speech therapist will provide individualized therapy to meet the person right where they are. They may work to maintain a person’s communication skills for as long as possible. They may also focus on new modes of communication such as augmentative and alternative communication, or AAC. This may involve teaching the person to use a device, written communication, or gestures to allow them to communicate as easily as possible. 

If you or someone you love begins speech therapy for one of these diagnoses, work closely with your therapist, and always ask any questions you have. Your speech therapist will be there to not only help the client, but also support family and friends involved in their care.

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