Childhood and adult factors associated with restless legs syndrome (RLS) diagnosis

Background and purpose: RLS appears to be caused by a complex interaction of genetic and environmental factors. This study sought to identify some environmental risk factors significantly associated with the occurrence of RLS. Patients and methods: Three adult behaviors and 10 childhood factors potentially related to development of RLS were evaluated for significant association with the occurrence of RLS in a large case-controlled family history study. All available family members of the probands in this study were evaluated for RLS using a validated diagnostic telephone interview that included a background questionnaire covering factors potentially associated with the development of RLS. Where possible, the mothers of the subjects were also interviewed regarding developmental factors that might affect the child's health and perhaps occurrence of RLS. All family members with a definite diagnosis of RLS or Not-RLS were included in the study. Of a total of 973 participants, 262 (27%) had RLS and 711 did not. Results: An odds ratio (OR) with 95% confidence limits (CI) was calculated for the relationship of each factor to RLS diagnosis. Restless sleep in childhood was associated with an increased risk of developing RLS later in life for both men (OR = 2.64; 95% CI: 1.31-5.29) and women (OR = 2.54; 95% CI: 1.41-4.59). Blood donation was also significantly associated with an increased risk of developing RLS among men only (OR = 1.99; 95% CI: 1.10-3.58), which was more pronounced for those donating blood more than the median number of donations for this group of five (OR = 2.3, 95% CI: 1.16-4.43). No other factor was significantly associated with the occurrence of RLS. Conclusions: This is the first case-controlled study that demonstrates a significant association between blood donation and the occurrence of RLS in males. The association was most significant for those men donating five or more times. Smoking and alcohol use were not related to the occurrence of RLS. Neither childhood growing pains nor attention-deficit hyperactivity disorder (ADHD) was related to RLS. The only consistent factor found related to prevalence of RLS for both men and women was the report of 'restless sleep' in childhood.