Tourette Syndrome is expressed differently in different people. In some, certain symptoms will predominate which in others are not present. For some it is overt tics that are the greatest difficulty. For others it may be obsessive thinking, impulsive and compulsive behaviours that are their most significant challenge. In many anxiety and social 'stresses' are a very significant problem.
No abrupt dividing lines can be defined between different 'aspects' of Tourette Syndrome. In most individuals, behaviours/impairments are complex, integrated and expressed as a seamless repertoire. Discrete 'fencing off' of symptoms/behaviours is subjective although some professionals tend to split symptoms into 'co-morbidities' by 'identifying' multiple single disorders. Such an approach is often seen as less representational of actual clinical phenotypes. Dysinhibition (impaired inhibition) and impaired selectivity are implicated in may aspects of TS especially tics, impulsivity, compulsions, obsessions and reactivity and also sensory hypersensitivity. Many symptoms are thought to be due to sensorimotor dysfunction and other structural/neuro-chemical developmental abnormalities in the basal ganglia, cortex, cerebellar and other regions of the brain.
It is difficult to be definitive about the causation of reading, writing and social communication difficulties, when present, due the complex influences involved. These present different difficulties according to the individual and their combination of symptoms. Reading and writing are often affected by obsessive and compulsive behaviours (OCB), simple or complex tics and may also be influenced by impaired attention/concentration (also affected by tics and OCB) and for many by sensory integration issues. Some vocal tics and motor tics are easily heard/seen by others although many are not, with only the person themselves being aware of them, and neural tic 'activity' does not appear to be limited to expressed vocal and motor impulses alone. Evidence suggests tic activity also influences sensory and cognitive processes. Tic behaviours often wax and wane and in many individuals become less problematic in adulthood or the individual becomes more adept at compensating and in suppressing them. Although tics may diminish with age in many, other aspects of TS may presist or become more problematic with time.
Low mood is a common aspect of TS and is a symptom recorded in up to 79% of individuals attending clinics. Evidence shows that, in TS, concentrations of the neurotransmitters, serotonin and nor-epinephrine (nor-adrenaline), in the brain, are low. Reduced serotonin and nor-epinephrine levels are known to be involved in low mood. The stresses and social stigma of living with TS are also likely to contribute greatly. Low serotonin is also thought to be involved in obsessive-compulsive behaviours in TS, although it is likely that neuroanatomical (structural) differences play an important role. TS-related OCBs show similarities to behaviours characteristic of classic psychiatric OCD however research indicates there are distinct and characteristic differences. TS-related OCB frequently proves highly resistant to standard pharmaceutical therapies, such as SSRIs, which are used to treat OCD in patients without TS. OCB in TS has a complex inter-relationship with tic behaviours, especially so-called 'complex tics' and reiterative and persistent thoughts. Many tics and OCBs have a strong 'just-right' aspect to them and may involve evening-up and symmetry and may have a numerical (or counting) component.
A comprehensive listing of peer-reviewed published research material/citations is available on this site for those who wish to read further. It must be borne in mind that TS is a 'complex' condition and distinct international differences of perspective are prevalent in the approach to research and interpretation of findings. Often diagnostic definitions influence research paradigms, data sampling and subsequent numerical analysis. Diagnostic definitions are also undoubtedly influenced by prevalent therapeutic regimes (especially pharmacotherapies) and the convenience of identifying treatable aspects of complex disorders such as TS. Much of the research to date has centered around tic behaviours and also symptom groups that are shared with other disorders such as obsessive behaviours, attention deficit and hyperactivity. There has been a recent increase in clinical research involving other non-tic symptomatologies of TS notably the social/language difficulties and cognitive and sensory dysinhibition/dysregulation.
