We congratulate Dr. Stefanidis and his coworkers for their beautiful and important study. They found significantly diminished mental-related scores in uremic patients with restless legs syndrome (RLS) compared with patients without RLS.1 This supports and expands our previous findings.2 The findings that RLS goes along with diminished mental-related scores are consistent both in patients with primary and secondary RLS. Another study in dialysis patients showed that most of the domains of the SF-36 were affected in RLS (except physical function).3 Our study supports that RLS itself tends to affect mental aspects independent of primary or secondary forms. In fact, the association of RLS with poor mental health has been noted in several epidemiological survey studies.4 We hypothesize that deteriorated mental aspects in RLS could relate to cognitive impairment. Although patients with RLS performed worse than normal controls on the prefrontal cognitive impairment,5 the cognitive deficits in RLS did not result from the chronic sleep disruption.6 Recently, an association between RLS and neuroticism has been additionally implicated.7 Further investigation about this issue in RLS is needed.
Takashi Nomura: Conception, organization, and execution of research project, design and execution of statistical analysis, writing of the first draft of manuscript and editing/review of final manuscript. Masayoshi Kusumi: Execution of research project, review and critique of statistical analysis, review and critique of final manuscript. Yusuke Uemura: execution of research project, execution of statistical analysis, review and critique of final manuscript. Kenji Nakashima: Conception and organization of research project, review and critique of statistical analysis, editing and review of final manuscript. Yuichi Inoue: Conception and Organization of research project, review and critique of statistical analysis, editing and review of final manuscript.
We thank Dr. Birgit Högl at Innsbruck Medical University for her helpful comment.
Takashi Nomura MD, PhD*, Masayoshi Kusumi MD, PhD*, Yusuke Uemura MD*, Kenji Nakashima MD, PhD*, Yuichi Inoue MD, PhD, * Department of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan, Japan Somnology Center, Neuropsychiatric Research Institute, Shibuya-ku, Tokyo, Japan.