Tourette’s syndrome is a neurological disorder characterized by involuntary, repetitive movements and vocalizations called tics. People with Tourette’s do not choose to have these tics and often report that they feel an irresistible urge to perform them. There has been much debate over whether Tourette’s is present from birth or develops later in life.
What causes Tourette’s syndrome?
The exact cause of Tourette’s is not known, but it is likely due to a combination of genetic and environmental factors. Research suggests that abnormalities in certain brain regions and chemical imbalances in the brain involving the neurotransmitters dopamine and serotonin play a role in the development of Tourette’s.
Genetics appear to be an important contributor, as Tourette’s tends to run in families. However, no single gene has been definitively linked to all cases of Tourette’s. Instead, multiple genes interacting with each other and the environment seem to influence risk. Most individuals with Tourette’s have a close family member such as a parent, sibling, or child who has tics or a more formal diagnosis.
Environmental factors
Certain environmental factors may also impact the development and severity of tics in Tourette’s syndrome, such as:
- Stress or anxiety
- Fatigue
- Illness
- Some medications
These factors may trigger or worsen tics, even though they did not directly cause the disorder. Some researchers believe that environmental factors may somehow switch on or off the genes that predispose someone to developing tics.
Is Tourette’s present from birth?
In most cases, Tourette’s does not appear to be present at birth. The first tics typically emerge between the ages of 5 and 7 years old, with the average age of onset being around 6 years old. Prior to the onset of tics, children tend to have uneventful medical histories and normal developmental milestones.
Some studies using specialized video footage have detected subtle tics in infancy that could potentially represent very early signs of Tourette’s. However, these transient tics are very common in babies and do not necessarily mean a child will go on to develop Tourette’s later in life. Only when tics persist and become chronic after the first few years of life is a diagnosis of Tourette’s considered.
Tic severity over time
In most individuals with Tourette’s, tic severity follows a waxing and waning course over time:
- Tics usually first emerge between 5-7 years old.
- Tics tend to worsen in frequency, intensity, and complexity through childhood and early adolescence, reaching peak severity between ages 10-12.
- Severity gradually declines for most patients as they move through the late teen years into adulthood.
- Although tics wax and wane over time, they do not fully remit in adulthood.
The course of Tourette’s helps demonstrate that it is not present from birth, but seems to develop and progress through childhood, adolescence, and adulthood.
Rare cases of persistent tics from infancy
In very rare cases, some infants may display persistent motor and vocal tics starting from their first year of life. If tics begin early and continue unabated for more than a year without significant improvement, this may represent a rare form of Tourette’s present from birth. However, most clinicians are hesitant to definitively diagnose Tourette’s before age 5 unless symptoms are severe and persistent.
Possible explanations
There are a few possible explanations for chronic tics emerging in infancy:
- Misdiagnosis: Infantile tics may be misdiagnosed as Tourette’s, when they are actually transient and not linked to the chronic disorder.
- Different subtype: There may be uncommon subtypes or variants of Tourette’s that uniquely manifest with very early onset tics.
- Environmental trigger: A prenatal or perinatal stroke, infection, or other neurological insult could trigger very early tic onset.
- Extreme genetics: A very strong genetic predisposition could lead to earlier emergence of tics.
Overall though, lifelong tic disorders emerging in infancy appear to be exceptionally rare and not representative of most cases of Tourette’s syndrome.
Does Tourette’s develop later in life?
Tourette’s syndrome is generally considered a childhood-onset neurodevelopmental disorder. Most individuals with Tourette’s experience their first tics before entering adolescence. However, in rarer cases, the onset of tics may occur later:
- Late childhood/adolescence: About 20% of people with Tourette’s first experience tics between 11-18 years old.
- Early adulthood: Approximately 5% of people report initial tic onset between ages 18-21.
- After age 21: Only around 4% of people with Tourette’s have their first tic after age 21.
When tics emerge after early childhood, this is referred to as “late onset Tourette’s syndrome.” The causes and clinical features of late onset Tourette’s may differ from typical childhood presentations:
Possible causes of late onset Tourette’s
- Delayed manifestation of genetic risk factors
- Unique genetic mutations
- Unmasking later in life due to a new environmental trigger
- Secondary causes like physical trauma, tumors, or infections
Characteristics of late onset Tourette’s
- Tics may be milder in nature
- Fewer behavioral comorbidities like OCD or ADHD
- Slower progression in tic severity
- More asymmetry between sides of body affected
Although tic onset after early childhood is considered atypical, Tourette’s syndrome can still legitimately develop later in life. Any age of onset should prompt an evaluation if tics are impairing daily functioning.
Is there a connection between PANDAS and late onset Tourette’s?
Some researchers have theorized that in rare cases, Tourette’s syndrome or tic disorders may suddenly emerge later in childhood following an autoimmune neuroinflammatory reaction called Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS).
PANDAS may develop when strep throat or scarlet fever triggers the immune system to mistakenly attack brain tissue, altering neurochemistry and leading to neuropsychiatric symptoms like:
- Abrupt onset of tics or obsessive-compulsive symptoms
- Deterioration in handwriting
- ADHD symptoms
- Developmental or behavioral regression
- Anxiety, irritability, depression
Symptoms typically emerge overnight and may resemble Tourette’s or OCD. While PANDAS is controversial, some research indicates it can explain why tics occasionally arise later in childhood in response to a specific environmental trigger like strep infection. However, most late onset Tourette’s cases cannot be linked to a post-infectious autoimmune cause.
Conclusion
In summary, the evidence indicates that Tourette’s syndrome is seldom present at birth. In most individuals, tics first emerge between ages 5-7 during early childhood. Tourette’s appears to be a neurodevelopmental disorder influenced by both genetic and environmental factors interacting over the first decade of life.
Cases of chronic tics from infancy and tic onset after adolescence are atypical and require more extensive diagnostic investigation. Tourette’s primarily develops during childhood, but the severity of tics waxes and wanes considerably over time. While not everyone is born with Tourette’s, a genetic predisposition combined with environmental triggers usually leads to onset of involuntary tics during early development.
