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 since 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.

What is the leading cause of stuttering in adults?

Leading cause of Stammering in Adults

Any child, adolescent or adult who began stuttering when they were between 2 and 4 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 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?

  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 on a gene on chromosome 7. In the case of females, stuttering was linked to a specific location on chromosome 15.
  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 pre-central 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 appear 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 multi-lingual children.
  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: the other factors that cause stuttering in adults

Adults who were fluent in speech can suddenly develop 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 –

Stammering causes
  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 neural degenerative 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.
  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 dysfluencies 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.

These are some of the lesser-known factors that can contribute to an adult stuttering –

  1. Stress – 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.
  2. Relapse of old stutter – 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 a 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.
  3. 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.