Speech and language disorders are problems or conditions that affect either how someone produces speech, or how they understand or use language. Speech is defined as the sounds that we produce to help us communicate with others. Language is how we get our meaning across to others, or understand their meaning when they communicate with us: basically how we compose sentences in our heads, and then express them.

There are several different conditions or disorders that affect speech and language. They are all barriers to effective communication—or more precisely, physiological barriers to communication. This page explains more about these conditions and signposts you to pages where you can find more information about each one.

Defining Speech and Language Disorders

Speech disorders are generally defined as those where the production of words is affected in some way.

This might be because of problems coordinating the muscles required to produce words, or because somehow the words do not come out of the mouth. One idea is that in some of these conditions, the messages between the brain and mouth get confused in some way.

Examples include:

• Stammering, where speech gets 'stuck' in either the brain or the mouth, and the person who stammers is unable to get the words out coherently;

• Cluttering, where your brain goes faster than your speech can follow, so that your sentences tend to be confused, and your word order may not be coherent;

• Verbal dyspraxia, where you may have trouble coordinating the movements required to speak, and which is often linked to dyspraxia more generally; and

• Dysarthria, a difficulty in speaking caused by muscle weakness, which is often found with conditions like Parkinson's or stroke.

Voice disorders can also be classified as speech disorders, because they affect the sound of the speech. They include hoarseness or losing your voice, as well as more complex issues like polyps or nodules and vocal fold paralysis.

Language disorders, by contrast, are those where the use of words is affected, but their production largely remains unchanged.

Examples include:

• Aphasia, where you cannot 'find' the right word in your head, even though you know it and often use it. You may even be able to describe its shape and meaning; and

• Developmental language disorder, where someone's use of language does not match their age or intellectual ability.

We can therefore distinguish between speech and language disorders by saying that people with speech disorders generally know what they want to say, but cannot get the words out. They can usually communicate highly effectively in writing or by typing, and sign language will be unaffected.

People with language disorders, by contrast, may struggle to know what to say because they cannot find the right word, or may be unable to put words together coherently into sentences. They will find it harder to communicate using words in any medium—out loud, via computer, or using sign language.

Prevalence of Speech and Language Disorders

Speech and language disorders are relatively common, especially among children.

In the United States, estimates suggest that around 3% of children aged between 3 and 17 years old are likely to have problems with speech, language or swallowing (which uses similar muscles) in any given year.

Among younger children, those aged between 3 and 6 years old, this rises to 11%.

In the United Kingdom, it is estimated that around 2 million children at any given time are likely to be experiencing some problem with speaking or understanding words.

Many speech and language disorders are more common among children. This may be partly because people 'grow out of' some of these issues, and also because treatment is quite effective. Problems with fluency in particular are often associated with the brain working faster than the muscles that make speech, so this issue will usually resolve by itself. Treatment is therefore often about providing coping strategies in the meantime, to avoid frustration.

However, some conditions are associated with disorders that are more common in older people. For example, dysarthria is often associated with Parkinson's or stroke, and aphasia is also a common result of stroke. Voice disorders are also more likely to occur in adulthood. This is because many are the result of overuse or abuse of the voice in some way, and this is often cumulative.

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Causes of Speech and Language Disorders

There are many different causes of speech and language disorders, and the same condition can also have several different possible causes.

This is why it is always worth getting conditions investigated.

For example:

• Hoarseness could just be the result of a bad cold, in which case it will go away after a week or two. However, it could also be a sign of some kind of growth on the vocal cords, such as nodules or polyps, or even throat cancer.

• Stammering and other dysfluencies are often genetic in origin, or at least genetically linked. However, they can also be associated with brain trauma of some kind, including growths within the brain.

• Articulation disorders, where words are not pronounced properly or are shortened inappropriately, are often familial or genetic in origin. However, they can also be an early sign of hearing loss. This is always worth investigating because it too can have a wide variety of causes, some more benign than others.

Treating Speech and Language Disorders

There is also a wide difference in duration and treatment of speech and language disorders.

Some conditions resolve spontaneously. Many others may need treatment. Some may endure for considerable periods of time, or even last for a lifetime. Treatment then is often about finding coping strategies or alternative forms of communication, rather than directly addressing the condition itself.

The same condition or disorder may even be acute in one person, and eventually resolve, and chronic in another.

It is always worth getting speech and language disorders investigated (see box), if only to check that the cause is benign. Speech therapy is often extremely effective in finding coping strategies even if no active improvement is possible.

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A Final Thought

A wide range of conditions and disorders fall under the heading of speech and language disorders.

They may have a variety of causes and effects, as well as lasting very different lengths of time. Some may spontaneously resolve without any treatment. However, it is still worth seeking professional advice if you or your child are experiencing one of these issues, because speech therapy is often extremely helpful either in resolving the condition, or providing alternative strategies for use in the short or longer term.

As a general rule of thumb, if either the person with the speech or language disorder or (for a child) their parent are concerned that the condition is affecting their ability to manage in everyday life, it is always worth asking for a referral to a speech and language therapist.

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