OCD (Obsessive Compulsive Disorder) or obsessive compulsive behaviours** (OCBs) and Tourette, as well as another tic disorder called Chronic Tic Disorder*, often appear together. Research shows these conditions are probably genetically linked and as a result, we tend to see both conditions run in families.
Before we discusses the risks of being born with these conditions, let’s look at some general stats on TS and OCD:
- 25%-50% of people with Tourette or Chronic Tic Disorder (CT) meet the criteria for a formal diagnosis of OCD
- 80% of people with Tourette or Chronic tic disorder may have obsessive compulsive behaviours
- 30% of people with OCD have a family history of co-occurring Tourette or Chronic Tic Disorder
- A lot of recent research including twin studies, neuroimaging studies, and a genome-wide complex trait analysis, suggest that there is a significant genetic association between TS and OCD (of .41)
A large study published in 2015 took a look at these two conditions. Here are some of the key results:
- If your oldest sibling has TS or chronic tic disorder plus OCD, you have a significantly higher likelihood of having these conditions.
– The risk of having TS or Chronic Tic Disorder (CT) plus OCD was higher for people who had an oldest sibling who was affected by these conditions
– People with an oldest sibling with TS/CT were 18 times more likely to have a diagnosis of either Tourette or Chronic Tic Disorder
– Individuals with an oldest sibling with OCD, were 5 times more likely to have an OCD diagnosis than a person who does not have an oldest sibling with OCD
- If you have a brother or sister with TS or Chronic tic disorder, you’re more likely to have these conditions than other people.
– If one of your siblings has TS or CT, you have a 9.88% risk of also having CT/TS
– If none of your siblings has TS or CT, you have 0.42% risk of having CT/TS
- If you have a brother or sister with OCD, you’re more likely to have these conditions than other people.
– If one of your siblings has OCD, you have a 4.01% of having it as well
– If none of your siblings have OCD, there is a 0.84% you will have it
- For full siblings with Tourette (same mom and same dad), the chance that their brother or sister will have TS is greater than for half-siblings (either same mom or same dad).
– This suggests that there is a genetic contribution or basis for TS/CT
What is does this all mean?
Simply put, this is what we know right now –if you have a family member with TS and OCD, you’re more likely to have TS and OCD too. Your chances of having TS and OCD are a lot greater if your older sibling has these conditions.
Please share your experiences or tell us what you think about this!
*Chronic Tic Disorder or CT: the presence of either involuntary motor or vocal tics
** Obsessive compulsive behaviours (OCBs): Reports show that 11-80% of patients with TS have OCB
Browne, H. A. et al. “Familial Clustering of Tic Disorders and Obsessive-Complusive Disorder” JAMA Psychiatry, 2015: 72 (4).
Carroll, Amber & Robertson, Mary. Tourette Syndrome A Practical Guide for Teachers, Parents and Carers. David Fulton Publishers: 2000.