Ask the MAB
Lawrence Scahill, MSN, Ph.D., is Professor of Nursing & Child Psychiatry at Yale University and is a member of the TAA Medical Advisory Board.
Q: Please define the differences between a Transient Tic Disorder, Chronic Motor Tic Disorder, Tic Disorder and Tourette Syndrome?
A: These labels come from the Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association. This professional group has tried to set down guidelines for making diagnostic determinations across a wide range of conditions including Tic Disorders. The term “Tic Disorder” is a general term that includes the list of conditions including: Transient Tic Disorder, Chronic Tic Disorder, and Tourette Syndrome. The distinction between these labels is related to the type of symptom present and the duration of tic symptoms.
Transient Tic Disorder is used when motor tics, vocal tics (or both) are present for more than two weeks – but less than one year. Chronic Motor Tic Disorder is the right diagnosis when motor tics – and only motor tics – have been present for a least a year for a year. Although it appears to be less common, Chronic Vocal Tic Disorder is defined by the presence of vocal tics (but no motor tics) for more than a year. The diagnosis of Tourette Syndrome requires the presence of multiple motor tics and at least one vocal tic persisting for at least a year.
In addition to the tics being present for more than a year, the diagnosis of TS requires that the tics be persistent (occurring daily) and there is no significant period of time when the tics are not present. As a guide, the DSM specifies three months, but this period of time is somewhat arbitrary. The intent is to confirm that the person has had an enduring pattern of tics that lasted at least a year. This issue often comes up in the clinic. For example, consider the case of an 8-year-old boy who started having tics at age 6. The parents will recall the onset of eye blinking that “lasted for a few months and went away.” Sometime later, the child showed facial grimacing – again lasting a few months and then subsiding. At age 7 ½ years, several tics appeared head jerking, throat clearing, blinking, grimacing. These tics occurred daily and this time they didn’t subside. At 8 years of age, he comes into the clinic with an enduring pattern of tics for the past six months – but tics were first noticed two years previously. Does this child have TS? The answer is probably. If the diagnostic criteria were strictly applied – a little more time would be needed.
Q: Is TS a neurological disorder, psychiatric disorder or a neurobehavioral disorder?
A: This is also a discussion about labels. There is a large body of evidence showing that tics are due to subtle disruption of specific nerve pathways in the brain. Not surprisingly, these nerve pathways have to do with motor action. In order for us to carry out everyday activities or even specialized activities like playing an instrument or hitting a baseball, we have to activate certain muscle groups and deactivate other muscle groups that aren’t needed for that action. Thus, coordinated motor action requires facilitation and inhibition of muscle groups at the same time. This coordination is managed by motor pathways in the brain. The involuntary performance of a tic may be a disruption of this balance between facilitation and inhibition of motor pathways. Taken together, this suggests that tics are neurological. But there may be a little more to it.
Careful observation by parents and individuals with TS indicates that tics occur in some situations more than others. Stressful situations, excitement (the Disneyland effect) and anxiety can increase tics. Motor activities involving high levels of concentration (playing the piano) can decrease tics. Recent success with habit reversal training suggests that people can learn techniques to alter or eliminate tics. These observations indicate that environmental factors and learning can influence tics. If environmental factors and learning can influence tics, maybe the term “neurological” is incomplete and that TS may be a bit more complicated than this term implies.
One of the problems with the term “psychiatric” is that our society is not over the stigma of mental illness. Because of this stigma, some people shy away from the idea that TS is a mental illness. Evidence compiled from neuroimaging and examination of brain tissue of patients with TS after death suggests that the division between neurological and psychiatric may not be as sharp as once believed. In keeping with view, some suggest the term neuropsychiatric. This term implies that there are both neurological and psychiatric elements in TS.
What about the term – neurobehavioral? As many parents of children with TS know, TS is often more than just tics. Children with TS are more likely than the general population to have problems with impulsiveness, over-activity, distractibility, disruptive and defiant behavior, repetitive behavior and anxiety. Some children with TS have lowered capacity for managing frustration and may over-react to what others consider minor frustration. It is not clear that these problems are part of TS – indeed not every child with TS has such problems. When present, however, these behavioral problems can be far more pressing than tics. Thus, neurobehavioral seems to fit – but consensus on what it means has not emerged.
In conclusion, TS is fundamentally a neurological disorder. Although it is defined by the presence of motor and vocal tics, to say that TS is only neurological suggests that it is only about motor and vocal tics. It is clear that environment influences behavior – including tics. Behavior also influences the environment. Children with TS who are impulsive, disruptive and defiant can pose a real challenge for parents. To promote optimal development for these children with TS, families and clinicians need to look beyond the tics.
Q: As my young son grows older, can he expect to see an increase or a decrease in his TS movements and sounds?
A: is now pretty convincing evidence that tics get better for most children by the end of their teenage years. The onset of tics is usually between 5 and 7 years of age. Following the onset, there is often observed waxing and waning pattern , but there may be a gradual worsening until about 11 years of age. After this “peak” there is often a gradual decline such that by 8 or 19 years of age the tics have subsided. The tics may not go away completely, but are likely to be reduced in a majority of cases.
There are two other important points here. First, as discussed above, tics may not be the whole story in TS. Therefore, even though the tics may be reduced, issues such as impulsiveness, distractibility, low frustration tolerance, disruptive behavior and the like, may not be resolved. Efforts to deal with these problems should start early. Successful management of these behavioral problems can improve long-term outcome.
Second, although tics subside in many cases, they persist in others. It is not clear in childhood which individuals will show persistent tics in adulthood. Tic severity does not appear to be a strong predictor. In other words, some children with mild tics in childhood have more tics in adulthood. Other children with prominent tics continue to have prominent tics in adulthood. The pattern is not clear.
In conclusion, chances are good that tics will improve for many children with tics by the end of their teenage years. But this pattern is not true for everyone with TS.