Objective

To determine if hyposmia in isolated REM sleep behavior disorder (IRBD) predicts short-term conversion to any α-synucleinopathy and declines with time.

Methods

Olfaction was tested using the University of Pennsylvania Smell Identification Test (UPSIT-40) in 140 consecutive patients with polysomnography-confirmed IRBD and in 77 matched controls. Patients were followed-up during 5.6 ± 3.9 (range 0.2–13) years. Twenty-one patients underwent serial UPSIT-40 evaluations at 1–3 and 4–6 years after baseline.

Results

UPSIT-40 score was lower in patients than in controls (20.2 ± 6.5 vs. 28.6 ± 5.0; p < 0.001). Hyposmia (UPSIT-40 score < 19 points) occurred in 42.9% patients. Forty-three (30.7%) patients developed Parkinson disease (PD = 27), dementia with Lewy bodies (DLB = 13) and multiple system atrophy (MSA = 3). Kaplan–Meier analysis showed that hyposmics had higher risk than normosmics to develop a synucleinopathy at the short term (p = 0.030). UPSIT-40 score was similar between patients who developed PD and DLB (p = 0.136). Normal smell occurred in all three (100%) IRBD patients who developed MSA, 12 of 27 (44%) who developed PD, and 4 of 13 (31%) that developed DLB. Serial UPSIT-40 evaluations showed no changes with time (p = 0.518).

Conclusion

In IRBD, hyposmia is a short-term risk for synucleinopathies but cannot distinguish underlying PD from DLB. Normosmia not only occurs in latent MSA but also in latent PD and DLB. In future IRBD neuroprotective trails, individuals at entry could be enriched for hyposmia, whereas serial evaluation of smell would not be useful to monitor the efficacy of a therapeutic intervention.

中文翻译：

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低血容量对孤立的REM睡眠行为障碍的意义

客观的

要确定孤立的REM睡眠行为障碍（IRBD）中的低血尿症是否可以预测短期内转化为任何α-突触核蛋白病并随时间下降。

方法

使用宾夕法尼亚大学气味识别测试（UPSIT-40），对140例经多导睡眠图检查确认的IRBD的连续患者和77个匹配的对照组进行嗅觉测试。在5.6±3.9（0.2-13年）范围内对患者进行了随访。21名患者在基线后1-3年和4-6年接受了连续UPSIT-40评估。

结果

患者的UPSIT-40得分低于对照组（20.2±6.5对28.6±5.0；p  <0.001）。低血尿症（UPSIT-40得分<19分）发生在42.9％的患者中。四十三（30.7％）例患者发生帕金森病（PD = 27），路易体痴呆（DLB = 13）和多系统萎缩（MSA = 3）。Kaplan–Meier分析表明，低剂量组在短期内发展为突触核蛋白病的风险要高于正常组（p  = 0.030）。发生PD和DLB的患者之间的UPSIT-40评分相似（p  = 0.136）。在三名（100％）患MSA的IRBD患者，27名中的12名（44％），PD以及13名中的4名（31％）患DLB的患者中，嗅觉均正常。连续UPSIT-40评估显示，时间没有变化（p  = 0.518）。

结论

在IRBD中，低血尿症是发生突触核蛋白病的短期风险，但不能区分潜在的PD和DLB。正常睡眠不仅发生在潜在的MSA中，而且还发生在潜在的PD和DLB中。在未来的IRBD神经保护试验中，进入时的个体可能会出现低渗血症，而嗅觉的连续评估对于监测治疗干预的有效性将无济于事。