Developmental & Acquired Causes of Stuttering in Adults

by Team Stamurai

Stuttering is a common speech fluency disorder. Today, between 0.72% and 1% of the world's population stutters. People who stutter include children, adolescents, adults, and the elderly. Some begin stuttering from early childhood and stutter well into their senior years.

There are several cases where children show symptoms of stuttering but recover on their own within a year or so. Then there are the others who stutter throughout their childhood and adulthood before seeking speech therapy.

Although rare, there are a few cases of sudden onset of stuttering in adults. In such cases, it is important to consult a medical professional as well as a speech-language pathologist to determine the causes of stuttering.

If someone develops stuttering as an adult, it may be a case of acquired stuttering. Keep reading to find out why you or someone you know may be developing a stutter in adulthood.

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What Causes Stuttering in Adults?

Any child, adolescent or adult who began stuttering when they were between 2 and 4 years old, has developmental stuttering. Developmental stuttering is the most common form of stuttering. The prevalence and incidence of developmental stuttering vary significantly per year according to country and region.

Roughly 2% of adults between the ages of 21 and 49 years stutter due to developmental reasons. Repetition of one-syllable words, silent or audible blocking, broken words or pauses, prolongation of vowels and consonants, and words produced with unnaturally high physical force are all symptoms of stuttering.

Why Does Developmental Stuttering Continue Well into Adulthood?

Can you develop a stutter in adulthood? Yes. However, a majority of the population begins stuttering in their early childhood and continues to do so in their later years due to lack of speech therapy and stuttering treatment.

Here are a few reasons why many individuals continue to stutter in their adulthood.

1. Genetic factors

More than 80% of the children who stutter typically have a family history of stammering. Multiple chromosomal aberrations may contribute to stuttering. Preliminary studies show that genes on chromosome 18 may contribute to developmental stuttering.

Studies by Cox and Yairi in 2000 have identified three chromosomes (16, 13 and 1) that may contribute to developmental stuttering. Another study by Riaz, Steinberg, Ahmad, Pluzhnikov, and Riazuddin et al. in 2005 has shown a strong link between genes on chromosome 12 with familial stuttering. In 2006, Wittke-Thompson et al. published a study that showed that chromosome 15 is associated with persistent stuttering.

Another recent study showed that in the case of males, stuttering was linked to a gene on chromosome 7. In the case of females, stuttering was linked to a specific location on chromosome 15.

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2. Brain Structure and Function

A study by Brown et al published in 2005 showed that people who stutter have lower activation of areas involved in auditory functions. The mechanisms associated with hearing one’s own speech may not function optimally in those who stutter.

fMRI studies have shown that people who stutter typically exhibit a higher right hemisphere activity during the speaking. The excessive activation of the right precentral sensorimotor complex is prevalent during speech tasks among children who stutter.

Studies by Chang et al. include the anatomical differences in the brain structure of children and adults who stutter.

3. Language

Stuttering begins in children when they are rapidly developing their language skills. It begins as children start using bigger words and longer sentences to express themselves. It is common for parents to notice symptoms of stuttering like repetitions, blocks and prolongations appearing for the first time in their children between the ages of 2 and 4 years.

Language factors have more impact on how a child stutters – like the beginning of a word that starts with a consonant. However, children who stutter have more phonological challenges as compared to those who don't stutter. There is no consistent result that indicates a higher prevalence of stuttering in multilingual children.

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4. Environmental Factors

Stressful environments can precipitate stuttering in already vulnerable children. Environmental stress can include an overly competitive household or sudden changes in the neighbourhood.

Unexpected changes to a child’s routine or sudden emotional trauma resulting from loss can worsen stuttering. However, predisposition and environmental factors work together to precipitate stuttering. Only stress does not induce stuttering in a child who has no history of stuttering in the family.

Most adults who stutter do so since their early childhood. Developmental stuttering often responds to regular and rigorous speech therapy. Speech language pathologists along with psychological counsellors can help adults reduce their frequency and intensity of stuttering over time.

Acquired Stuttering: What Causes People to Develop a Stutter Suddenly in Adulthood

Adults who are fluent in speech can experience the sudden onset of stuttering. Acquired stuttering is the broad term for this condition. It can happen due to multiple physical, psychological and psychosomatic factors.

If someone you know begins stuttering in their adulthood, you should treat the situation with urgency and seriousness.

Here are the different types of acquired stuttering that can affect adults –

1. Neurogenic Stuttering

It is an acquired speech disorder that generally arises after trauma to the brain. It can be the result of a cerebral vascular accident (CBA) or a neurodegenerative disease.

In at least 50% of the cases, aphasia, verbal apraxia or dysarthria accompanies neurogenic stuttering.

Medical history and comorbid conditions play critical roles in the differential diagnosis of neurogenic stuttering. One sign of neurogenic stuttering is that it can occur at any location on a word. The stutter does not have to be at the beginning of the word or its second syllable.

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2. Psychogenic Stuttering

This type of stuttering in adults arises from psychological factors. It may occur alongside other psychological disorders. Often psychogenic stuttering is the result of severe emotional trauma. It can also occur due to prolonged psychological trauma.

It is extremely rare. Many psychologists and speech therapists consider it a conversion reaction. Medical history of the individual is important for the differential diagnosis. It can help rule out other forms of acquired stuttering.

You should remember that the presence of neuropathy does not invalidate the diagnosis of psychogenic stuttering.

3. Pharmacogenic Stuttering

New medication or an overdose can cause sudden stuttering in adults. Medical research shows that drugs like broncho-dilator theophylline, selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants can cause stuttering-like disfluencies in adults as a side effect.

Drug-induced stuttering is distinct from neurogenic stuttering. Speech therapists and medical professionals can work together to reverse the effect of the medicinal compound. It may be necessary to reconstruct the recent drug history of the person, vary the dose or replace the drug entirely to stop the stuttering.

4. Lesser-known factors that can contribute to new stuttering in adults –


Only stress rarely precipitates stuttering in adults who are not predisposed to the disorder. However, it does happen. For example, severe stress caused by financial issues or bereavement can trigger speech disorders. Even a car crash or a similar accident can cause them to stutter. It is rather difficult for doctors and speech therapists to determine stress as the causal factor because the brain scans and other neurological examinations do not know any aberrations in the brain structure or function.

A Relapse of Old Speech Disfluencies

Relapse is a common cause of stuttering in adults. Dr Charles Van Riper and Dr Barry Guitar state that when preschool aged children recover from developmental stutter, they may not have a memory of their speech impediment at all. Psychological stress, emotional trauma and anxiety in adulthood, and other factors like change in medication or neurological stress can lead to the relapse of old speech disfluencies in adults. If the person does not have a record of their childhood disfluencies, treatment and recovery, it may seem like a sudden onset without a prologue.

Spasmodic Dysphonia

It is a comparatively rare disorder that presents itself as a recurring block of the larynx (voice box). It typically begins in the middle-age. Spasmodic dysphonia causes involuntary spasms in the larynx muscles. It causes the voice to break and it can create a strangled or strained sound. The problems can range from not being able to produce a particular sound while speaking to the inability to talk.

The effects are sometimes very similar to stuttering in adults.

Stuttering is a complex speech fluency disorder that can occur in children and continue until their adulthood. An adult can begin stuttering suddenly. However, that is an immediate cause for concern since it signifies neurological, or psychological disorders or the side effects of a new medication.

Why have I started stuttering in my adulthood?

The plausible reasons for the sudden onset of stuttering will depend upon multiple factors, such as -

  • Any history of speech disfluencies
  • Co-existing medical conditions
  • Recent development of health issues like a cerebrovascular disease or neurodegenerative disorder
  • Occurance of a traumatic brain injury, brain tumor, or brain surgery
  • New medication or changing the dose of an existing medication like a selective serotonin reuptake inhibitor (SSRI)
  • A recent traumatic event or exposure to prolonged emotional/psychological trauma

One or more of these factors can contribute to the onset of speech disfluencies in adulthood. It is impossible to state why you have begun stuttering suddenly without a full health checkup.

If you have a history of brain injuries, tumors, surgeries or neurodegenerative diseases, your doctor might recommend brain imaging studies to understand the cause of your stuttering.

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2. Can you develop a stutter later in life?

Although rare, it is completely possible to begin stuttering later in life (as an adult). Some adults may find themselves slowly beginning to stutter, while others may find themselves in the middle of repetitions and blocks quite unexpectedly. The nature of the stutter will depend upon the cause. To know more about the potential causes of stuttering in adulthood please refer to the article.

3. Why do I stutter sometimes?

Every individual experiences some extent of speech disfluency throughout the day. At the same time, a person who stutters may not do so every time they speak. Some PWS report increased frequency and intensity of stuttering when they are anxious, afraid, stressed or worried.

Someone who stutters may do so on about 10% of the words while speaking or reading aloud. On the other hand, someone who stutters mildly may do so on around 5% of the words while reading aloud.

It is quite normal for a child to stutter, but it is rare for adults to begin stuttering without a history of speech problems! You should consider speaking to a speech-language pathologist (SLP) and your doctor (GP).

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4. Why have I been stuttering so much lately?

Did you stutter as a child? If so, then it may not be a new speech disfluency but a relapse of your old stutter.

Relapses may occur due to lack of practice, as well as increased stress. Stress does NOT cause stuttering, but it can worsen existing speech disfluencies.

If you have no history of stuttering then you should speak to a medical health professional and a speech-language pathologist (SLP). A sudden onset of stuttering in adulthood may have one or more causes. Your stuttering may be neurological, drug-induced, or psychological.

It is important to consult your GP, neurologist, psychologist/psychiatrist and SLP to determine the exact cause(s) of your stuttering.

5. Can adulthood stuttering be cured?

In case you are not experiencing a relapse of developmental stuttering (childhood-onset fluency disorder) there may be a cure.

The treatment depends upon the nature of your acquired stutter.

Neurogenic stuttering typically occurs due to anomalies or disturbances in the brain structure and function. Your neurologist or neurosurgeon may be able to guide you towards the right course of treatment. Speech-language pathologists (SLPs) and speech therapists play integral roles in the treatment of neurogenic stuttering in adults.

Psychogenic stuttering may have its roots in deep-seated emotional or psychological trauma. It may be a part of PTSD. In such cases, you may need the help of a psychologist, psychiatrist and/or cognitive behavioral therapist to overcome your acquired stuttering. Cognitive behavioral therapy (CBT) can help you significantly in overcoming the anxiety and anticipation related to stuttering. Mental health professionals may even recommend prescription medication temporarily to reduce the intensity and frequency of your stuttering.

Pharmacogenic or drug-induced stuttering occurs due to a side effect of medicines. Some medicines can not only make stuttering worse, but they can induce stuttering in previously fluent people. If you have started taking a new medication or changed the dose of an existing medicine before your stuttering began, you may want to talk to the concerned doctor about it. Typically, drug-induced stuttering can be reversed by replacing or adjusting the dose of the drug.

6. Can ADHD cause stuttering in adults?

Attention Deficit Hyperactivity Disorder (ADHD) may cause speech problems and poor articulation. However, these speech issues are more likely to be present since the early childhood of the person who has ADHD.

It is unlikely for an adult who has had ADHD since childhood to develop speech disfluencies as a result of it.

If you are living with ADHD and experiencing a sudden onset of stuttering you should speak to your psychiatrist and general physician immediately.

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7. Can speech therapy help adults reduce the instances of acquired stuttering?

Speech therapy works across all ages. The time it takes to work may increase with increasing age.

That being said, the cause of your acquired stuttering will influence the efficacy of speech therapy. You may need help from your doctor to cope with acquired stuttering.

Adults can benefit from stuttering modification and fluency shaping strategies. Learn more about them right here!

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