Secondary causes of restless legs syndrome in older people

Abstract

Background: secondary causes of restless legs syndrome (RLS) have been reported to be more common in those with late-onset RLS. However, 'late-onset' in previous studies was defined as onset after 45 years. Objective: to determine the prevalence of secondary causes of RLS and the relationship between aetiological factors and age of symptom onset in an older population. Design: prospective study conducted over a 5-year period. Participants: 80 consecutive non-related patients diagnosed with RLS. Measurements: patients were assessed according to a standard protocol. Age at symptom onset, severity of symptoms, neurological findings and laboratory tests were examined. Results: iron deficiency (serum ferritin <50 ng/ml) was present in 22% of patients with onset before 50 years, 39% of those with onset at 50 to 64 years and 58% in those with onset after 64 years (P=0.009). Clinical neuropathy was also more common in older-onset patients (P= 0.08). Family history was positive in 39%, 23% and 8% of these groups, respectively (P= 0.008). Conclusion: secondary causes of RLS become more common and a positive family history less common with increased age, of symptom onset.