@article{oai:shiga-med.repo.nii.ac.jp:00003277,
 author = {角, 幸頼 and 松尾, 雅博 and 中林, 孝夫 and 増田, 史 and 高橋, 正洋 and 加根村, 隆 and 栗山, 健一 and 山田, 尚登 and 鷹見, 将規 and 角谷, 寛 and SUMI, Yukiyoshi and MATSUO, Masahiro and Nakabayashi, Takao and Masuda, Fumi and TAKAHASHI, Masahiro and KANEMURA, Takashi and Kuriyama, Kenichi and YAMADA, Naoto and TAKAMI, Masanori and KADOTANI, Hiroshi},
 issue = {16},
 journal = {Sleep Science and Practice},
 month = {Aug},
 note = {Background
This descriptive study was conducted to examine the changes in the symptom frequency in patients with rapid eye movement (REM) sleep behavior disorder (RBD) without medical intervention, in order to determine the association of RBD symptom frequency with disease duration.

Methods
Data were collected from 70 consecutive RBD patients who visited the Sleep Clinic in Shiga University of Medical Science. RBD symptom frequencies at the first visit to the clinic were quantified based on the reports by the patients and their family members.
For quality assurance, patients living alone or those with cognitive decline were excluded. Finally, 50 patients with family-confirmed symptom history were enrolled. The symptom frequencies were converted to a unit that reflects the estimated number of nights in a year affected by RBD (NAR). Using NAR, we observed the relation between RBD symptom frequency and the disease duration.

Results
Of the 50 patients, 41 were male and 9 were female, consistent with the male-dominant nature of this disease. The mean age at RBD onset was 62.2 ± 9.1 years, and the mean disease duration at the time of visit was 6.0 ± 4.9 years. The median symptom frequency was 50 NAR, with a 1st quantile value of 24 NAR and a 3rd quantile value of 115 NAR. When RBD symptom frequency was plotted against disease duration, we found that the frequency was lowest in the first 2 years of RBD (median, 18; range, 2–29 NAR), and higher frequencies were found in 2-year bin groups from 2 to 8 years after RBD onset (median, 60; range, 50–150 NAR). Intriguingly, after 8 years of RBD, the frequency returned to a level comparable to that in the first 2 years of RBD (median, 50; range, 12–100 NAR).

Conclusions
There was no association between RBD symptom frequency and disease duration. RBD  linical symptoms could be less prominent when neural damage becomes severe. Therefore, a natural decrease in RBD symptom frequency may be indicative of progression of neurodegeneration., Journal Article},
 title = {Changes in the symptom frequency of rapid eye movement sleep behavior disorder according to disease duration},
 volume = {1},
 year = {2017}
}