Christensen Ib Thrane, Larsson Elna-Marie, Holm Ida E, Nielsen Ole B F, Andersen Stig
Department of Geriatric Medicine, Aalborg University Hospital, Hobrovej 18-22, 9000, Aalborg, Denmark.
Department of Radiology, Aalborg University Hospital, Aalborg, Denmark.
BMC Geriatr. 2017 Jun 20;17(1):129. doi: 10.1186/s12877-017-0516-2.
Alzheimer's disease (AD) is the most common cause of dementia and early and accurate diagnosis is important. Olfactory dysfunction is an early sign of AD. The contribution by test of olfactory function has been surveyed in AD vs a line of conditions but remains to be settled in the workup of unselected patients referred with suspected dementia.
We performed a two-step investigation: first, a comparative study of healthy controls and probable AD patients to test the applicability of the chosen scents (cuisine study); second, a study of consecutive patients referred to our geriatric outpatient clinic for suspected dementia with the investigating personnel blinded to the results of the Olfactory Test (blinded study).
The sum of scents detected discriminated patients with probable AD from controls in the cuisine study (n = 40; p < 0.001; area under ROC curve 0.94). In the blinded study (n = 50) the diagnosis was probable AD in 48%, minimal cognitive impairment in 24%, vascular dementia in 8%, alcohol induced impairment in 12%, depression in 4%, and Parkinson's disease and Lewy body dementia in 2%. Area under the ROC-curve was 0.67. The odds ratio for probable AD with 2+ smell errors was 12 (95%-CI: 1.3-101; p = 0.026 (reference 0-1 smell errors)) age adjusted. None in the AD group had zero smell errors (Negative Predictive Value 100%).
Olfactory testing may support to dismiss the diagnosis of probable AD in the workup of a mixed group of patients referred with cognitive impairment. Still, it had a low sensitivity for probable AD.
阿尔茨海默病（AD）是痴呆最常见的病因，早期准确诊断至关重要。嗅觉功能障碍是AD的早期迹象。嗅觉功能测试在AD与一系列病症中的作用已得到研究，但在对疑似痴呆的未筛选患者进行检查时，其作用仍有待确定。
我们进行了两步调查：首先，对健康对照者和可能患有AD的患者进行比较研究，以测试所选气味的适用性（烹饪研究）；其次，对连续转诊至我们老年门诊疑似痴呆的患者进行研究，研究人员对嗅觉测试结果不知情（盲法研究）。
在烹饪研究中（n = 40；p < 0.001；ROC曲线下面积为0.94），检测到的气味总和可区分可能患有AD的患者与对照者。在盲法研究中（n = 50），48%的诊断为可能的AD，24%为轻度认知障碍，8%为血管性痴呆，12%为酒精所致损害，4%为抑郁症，2%为帕金森病和路易体痴呆。ROC曲线下面积为0.67。年龄校正后，有2个及以上嗅觉错误的可能患有AD的比值比为12（95%可信区间：1.3 - 101；p = 0.026（参考值0 - 1个嗅觉错误））。AD组中无人嗅觉错误为零（阴性预测值为100%）。
嗅觉测试可能有助于在对认知障碍转诊的混合患者群体进行检查时排除可能患有AD的诊断。不过，其对可能患有AD的敏感性较低。
