Welge-Lüssen A
Department of Otorhinolaryngology, University Hospital Basel, Basel, Switzerland.
B-ENT. 2009;5 Suppl 13:129-32.
Olfactory and gustatory disorders increase with advancing age. Moreover, olfactory disorders are common in neurodegenerative disorders, especially in idiopathic Parkinson's disease (IPD) and Alzheimer's Disease (AD). Since the decrease in olfactory function is usually gradual, it often remains undetected. Given the poor self-assessment of olfactory function, olfactory testing is mandatory in suspected cases to establish the diagnosis of hyposmia or anosmia. The high rate of anosmia over the age of 70 is suspected to be due to several factors such as changes in the olfactory epithelium (reduced mucus secretion, hormonal changes, changes in epithelial thickness, for example), and the reduced neuroregeneration rate in olfactory receptor cells themselves. There is no known adequate treatment for stopping or reversing this age-related decline in olfaction. In IPD, olfactory impairment precedes motor symptoms by years and is independent of dopaminergic loss. Using fMRI, altered neuronal activity in the amygdaloid complex and hippocampal formation during olfactory stimulation have been demonstrated, as has a link between the expression of olfactory event-related potentials and olfactory-induced brain activity. In AD--by contrast with IPD--the severity of the disease and the olfactory disorder correlate. The olfactory disorders alone, however, cannot distinguish between AD and IPD. A complete loss of gustatory function is rare, while dysgeusia is common, especially with increasing age. There are multiple possible explanations, including concomitant disease and the side-effects of medication. These need to be established on the basis of exact history and examination. Treatment remains difficult.
嗅觉和味觉障碍会随着年龄的增长而增加。此外，嗅觉障碍在神经退行性疾病中很常见，尤其是在特发性帕金森病（IPD）和阿尔茨海默病（AD）中。由于嗅觉功能的下降通常是渐进的，所以往往难以察觉。鉴于对嗅觉功能的自我评估较差，对于疑似病例，必须进行嗅觉测试以确诊嗅觉减退或嗅觉丧失。70岁以上人群中嗅觉丧失率较高，这可能是由于多种因素造成的，例如嗅觉上皮的变化（如黏液分泌减少、激素变化、上皮厚度改变等），以及嗅觉受体细胞自身神经再生率降低。目前尚无已知的有效治疗方法来阻止或逆转这种与年龄相关的嗅觉衰退。在IPD中，嗅觉障碍比运动症状早出现数年，且与多巴胺能丧失无关。使用功能磁共振成像（fMRI）已证实，嗅觉刺激期间杏仁核复合体和海马结构中的神经元活动发生改变，嗅觉事件相关电位的表达与嗅觉诱发的脑活动之间也存在联系。与IPD不同，在AD中，疾病严重程度与嗅觉障碍相关。然而，仅嗅觉障碍无法区分AD和IPD。味觉功能完全丧失很少见，而味觉障碍很常见，尤其是随着年龄的增长。其原因有多种可能，包括伴随疾病和药物副作用。这些需要根据确切的病史和检查来确定。治疗仍然困难。
