Q: Professor Dressler, you have just completed a study on excessive stress triggering the onset of idiopathic cervical dystonia. What is the background?
Dressler: Idiopathic cervical dystonia is by far the most common form of cervical dystonia. Idiopathic means that there is only cervical dystonia and that it occurs without any identifiable cause. Genetics appear to play a role, as a number of associated gene defects have been identified and the condition typically runs in families. However, when gene defects are identified, only a few percent of gene defect carriers actually develop the condition. This means that there must be additional factors that trigger the manifestation of the gene defects. These factors are known as epigenetic factors.
Q: What do we know about these epigenetic factors?
Dressler: Very little. Stress has been implicated in these speculations since cervical dystonia was first described. However, most of these reports are anecdotal. There is virtually no published evidence. This is what we wanted to change.
Q: What did you do?
Dressler: We collected 100 consecutive patients with idiopathic cervical dystonia from our clinics and described the natural course of their disease. In 13 of these patients, we found that excessive psychological stress preceded the onset of cervical dystonia.
Q: How was this excessive stress defined?
Dressler: It was defined as the worst stress the patients had ever experienced before and after the onset of their cervical dystonia.
Q: Can you give examples of these stressful situations?
Dressler: There were partner conflicts, including divorce, separation and domestic violence. There were special family burdens, legal disputes and migration. Some patients even had several of these factors combined.
Q: How was the onset of cervical dystonia related to stress?
Dressler: Cervical dystonia started 8.3±3.9 months (mean±standard deviation) after the onset of the stress.
Q: Was the cervical dystonia in these patients unique or special?
Dressler: The clinical presentation of their cervical dystonia was indistinguishable from idiopathic cervical dystonia without psychological stress. However, its course was very different: in 85% of our patients, the onset of cervical dystonia was very rapid. It took only 5.8±4.4 weeks for the cervical dystonia to reach maximum severity. This usually takes several years. 2.7±0.8 years after disease onset, remission began. Eventually, the disease severity decreased to 54.5±35.3% of the maximal severity. Again, this was very different from idiopathic cervical dystonia without psychological stress, where remissions are very rare and only mild. In short, cervical dystonia with psychological stress has a very rapid onset and an unusually good chance of remission.
Q: Why are your findings important?
Dressler: For the first time, we have described in detail a relatively large number of patients with idiopathic cervical dystonia in whom psychological stress seems to be the trigger for its manifestation. With this, we can now differentiate three main types of interactions between stress and dystonia: 1) Stress can be a trigger for the manifestation of dystonia. 2) Stress may modulate the severity of existing dystonia. 3) Stress may cause psychogenic dystonia.
Q: Any warnings?
Dressler: Everything we have said so far refers to idiopathic dystonia. Psychogenic or functional dystonia is a completely different condition. Although psychological stress can play an important role in the development of dystonia: Dystonia is not psychogenic in the vast majority of patients.
Q: What are the mechanisms linking stress and the development of idiopathic dystonia?
Dressler: This is largely unknown. Some potential mechanisms have been suggested in the literature, but they are very vague.
Q: Strictly speaking, your study was on cervical dystonia. Do you think that your findings apply to other forms of dystonia?
Dressler: You are absolutely right. Other forms of idiopathic dystonia would also need to be studied, before we could make definitive statements. However, it would be plausible that basic mechanisms such as those described here also apply to other forms of dystonia.
Q: So far, you have studied patients with massive psychological stress. Could the same mechanisms explain why milder stress modulates dystonia?
Dressler: It would not be surprising, if the same mechanisms were responsible for the dystonia-modulating effects of milder stress. This could have far-reaching implications for therapeutic considerations.
Q: What is the outlook?
Dressler: If we understand epigenetics and the mechanisms involved, we might be able to intervene. This could lead to preventive therapies for idiopathic dystonia in patients at risk. Even in patients where idiopathic dystonia has already manifested, modulating these mechanisms might allow us to reduce its severity. This would be the first causal therapy. Both would be major breakthroughs.
The original publication will appear as:
Dressler D, Kopp B, Pan L, Adib Saberi F (in press) Excessive Psychological Stress Preceding the Onset of Idiopathic Cervical Dystonia. J Neural Transm