A survey of lifestyle factors in dystonia

Abstract Background Knowledge about what causes dystonia is highly incomplete, especially about the impact of nongenetic factors. Aims of the Study This cross‐sectional survey‐based explorative study examined different nongenetic factors in patients with dystonia. Methods Information from both medical records and a questionnaire was collected. In total, 220 patients with dystonia were identified, of which 51 participated in the survey. Results Women had a higher prevalence for cervical dystonia than men. Smoking was approximately twice as common in our studied population compared to the general Swedish population. Significantly more men than women met the criteria for low level of physical activity, yet the proportion of missing data was high in this category. Conclusions Conclusions on causality cannot be drawn in this preliminary study, further research is encouraged regarding the link between smoking and dystonia.


| INTRODUC TI ON
"Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned, twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action associated with overflow muscle activation." (Albanese et al., 2013).
Dystonia was first described in 1911, but still today the definition is being updated and debated (Albanese et al., 2013;De Pablo-Fernandez & Warner, 2017). The latest updated definition, quoted above, was presented in 2013. In addition to motor symptoms, increasing evidence indicates that nonmotor symptoms are troublesome for patients (Stamelou et al., 2012), leading to reduced quality of life (Müller et al., 2002;Timmers et al., 2017). Nonmotor symptoms can be pain, impaired sensory functions, neuropsychiatric disorders, sleep disturbances, and cognitive disturbances (Kuyper et al., 2011;Stamelou et al., 2012).
There is a reported connection between dystonia and psychiatric disorders, such as generalized anxiety disorder, obsessive-compulsive disorder, alcohol dependence, and depression. Whether these symptoms are effects of dystonia or side effects of treatment remains unclear.
A coherent understanding about the prevalence and risk factors for dystonia is still missing. Studies on prevalence of dystonia present varying numbers, ranging from 5 to 40 per 100,000 (Government of Canada and Neurological Health Charities Canada, 2014;Steeves et al., 2012) A systematic review by Krewski et al. (2017) found possible susceptibility to cervical dystonia among females. For blepharospasm, they proposed that there is no significant gender difference. Higher, rather than lower, consumption of coffee and alcohol has shown to be protective for onset of specific forms of dystonia, blepharospasm, and myoclonal dystonia, respectively, although the protective effect of alcohol is debated (Krewski et al., 2017).
The questionnaire contained two parts. The first part consisted of questions related to diagnosis, education, and caffeine consumption. The second part was a standardized questionnaire, with questions about lifestyle, more specifically about exercise, the use of tobacco and alcohol, and dietary habits. women with dystonia to men with dystonia, the p-value was calculated using chi-square test. Level of significance was set to 0.05.

| RE SULTS
Mean age of all 220 patients was 63 years (SD ± 15 years). Time since dystonia diagnosis ranged from 0 to 61 years, with median (interquartile range) of 12.6 years (3.9-21.5 years). Of these patients, 154 (70%) were women, 145 (66%) had cervical dystonia, and 176 (80%) had no other recorded disease, except for dystonia. Significantly more women had cervical dystonia, but no gender differences were seen in the smaller groups of blepharospasm, oromandibular dystonia, hereditary dystonia, other specified dystonia, or unspecified dystonia.
A total number of 51 patients were included in the survey, 75% were women (Table 2). Mean age for women was 68 years (SD ± 10.4 years) and for men 67 years (SD ± 12.7 years). Seventyfive percent of the patients had cervical dystonia, the remaining had blepharospasm, oromandibular dystonia, or other specified dystonia. Hazardous drinking (alcohol)-more than 9/14 (women/men) standardized units of alcohol per week, or 4/5 (women/men) or more units at one occasion, one or more times per month.
Low level of physical activity-One who does not meet the requirements of 150 min per week of moderate activity (e.g. walking, bicycling and gardening) or 75 min per week of intense activity (e.g. running and other sports).
Unhealthy eating habits-0-4 points out of 12 points, calculated from 4 questions about weekly intake of vegetables, fruit, fish and pastry/candy/crisps. Each answer renders 0-3 points depending on how frequent the intake is.

TA B L E 2 Demographics of survey responders (N = 51)
Diagnosis n Only two patients had parkinsonism, one with orofacial dystonia and one with hemifacial spasm.

Mean disease duration (years)
Patients' answers to lifestyle questions are presented in Table 3.
There was a gender difference in terms of low level of physical activity, where men were significantly more inactive than women. The seven men who were most inactive had cervical dystonia (n = 4), hemifacial spasm (n = 2), and other specified dystonia (n = 1), thus with similar distribution of dystonia subtypes compared with the whole sample. For visual comparison, statistics for the same questions from the general population is presented, collected by the Public Health Agency of Sweden (PHAS) and the NBHW. Daily tobacco smoking was twice as common in our dystonia patients as in the general Swedish population. Statistical analysis was not performed due to the small number of dystonia patients. Furthermore, only 31.6% of the women in our study had never been smokers.

| D ISCUSS I ON
Knowledge about nongenetic factors and their correlation to dystonia is very limited. This study aimed at learning more, through a lifestyle questionnaire sent out to 170 patients with dystonia. It should be considered as a preliminary study looking for any correlations with lifestyle factors to suggest further studies on causality or possible risk factors. The response rate was rather low, 32%, which is an interesting finding in itself. Our experience with other movement disorders, such as Parkinson's disease (PD), is quite different. PD patients generally have much higher response rates in similar studies, and it is also a group that is well-known for nonuse of tobacco and caffeine (Marras et al., 2019).
In the present study, age did not differ between women and men with dystonia, which is consistent with previous studies. However, significantly more women were diagnosed with dystonia, compared to men. This has been described in previous studies of all types of dystonia (Pekmezović et al., 2003) and cervical dystonia (Marras et al., 2007) Among patients with cervical dystonia, significantly more were female than male. These findings are consistent with those of Krewski et al. (2017)