PDF(Pubmed)
Abstract：
BACKGROUND: Strong evidence suggests that olfactory dysfunction (OD) can predict additional neurocognitive decline in neurodegenerative conditions such as Alzheimer\'s and Parkinson\'s diseases. However, research exploring olfaction and cognition in younger populations is limited. The aim of this review is to evaluate cognitive changes among non-elderly adults with non-COVID-19-related OD.
METHODS: We performed a structured comprehensive literature search of PubMed, Ovid Embase, Web of Science, and Cochrane Library in developing this scoping review. The primary outcome of interest was the association between OD and cognitive functioning in adults less than 60 years of age.
RESULTS: We identified 2878 studies for title and abstract review, with 167 undergoing full text review, and 54 selected for data extraction. Of these, 34 studies reported on populations of individuals restricted to the ages of 18-60, whereas the remaining 20 studies included a more heterogeneous population with the majority of individuals in this target age range in addition to some above the age of 60. The etiologies for smell loss among the included studies were neuropsychiatric disorders (37%), idiopathic cause (25%), type 2 diabetes (7%), trauma (5%), infection (4%), intellectual disability (4%), and other (18%). Some studies reported numerous associations and at times mixed, resulting in a total number of associations greater than the included number of 54 studies. Overall, 21/54 studies demonstrated a positive association between olfaction and cognition, 7/54 demonstrated no association, 25/54 reported mixed results, and only 1/54 demonstrated a negative association.
CONCLUSIONS: Most studies demonstrate a positive correlation between OD and cognition, but the data are mixed with associations less robust in this young adult population compared to elderly adults. Despite the heterogeneity in study populations and outcomes, this scoping review serves as a starting point for further investigation on this topic. Notably, as many studies in this review involved disorders that may have confounding effects on both olfaction and cognition, future research should control for these confounders and incorporate non-elderly individuals with non-psychiatric causes of smell loss.
METHODS: We performed a structured comprehensive literature search of PubMed, Ovid Embase, Web of Science, and Cochrane Library in developing this scoping review. The primary outcome of interest was the association between OD and cognitive functioning in adults less than 60 years of age.
RESULTS: We identified 2878 studies for title and abstract review, with 167 undergoing full text review, and 54 selected for data extraction. Of these, 34 studies reported on populations of individuals restricted to the ages of 18-60, whereas the remaining 20 studies included a more heterogeneous population with the majority of individuals in this target age range in addition to some above the age of 60. The etiologies for smell loss among the included studies were neuropsychiatric disorders (37%), idiopathic cause (25%), type 2 diabetes (7%), trauma (5%), infection (4%), intellectual disability (4%), and other (18%). Some studies reported numerous associations and at times mixed, resulting in a total number of associations greater than the included number of 54 studies. Overall, 21/54 studies demonstrated a positive association between olfaction and cognition, 7/54 demonstrated no association, 25/54 reported mixed results, and only 1/54 demonstrated a negative association.
CONCLUSIONS: Most studies demonstrate a positive correlation between OD and cognition, but the data are mixed with associations less robust in this young adult population compared to elderly adults. Despite the heterogeneity in study populations and outcomes, this scoping review serves as a starting point for further investigation on this topic. Notably, as many studies in this review involved disorders that may have confounding effects on both olfaction and cognition, future research should control for these confounders and incorporate non-elderly individuals with non-psychiatric causes of smell loss.
摘要：
背景：强有力的证据表明，嗅觉功能障碍（OD）可以预测神经退行性疾病如阿尔茨海默病和帕金森病的额外神经认知能力下降。然而,在年轻人群中探索嗅觉和认知的研究是有限的。本综述的目的是评估非COVID-19相关OD的非老年人的认知变化。
方法：我们对PubMed，OvidEmbase,WebofScience,和科克伦图书馆在制定这一范围审查。感兴趣的主要结果是小于60岁的成年人的OD和认知功能之间的关联。
结果：我们确定了2878项研究的标题和摘要综述，167正在进行全文审查，和54选择用于数据提取。其中,34项研究报道了限制在18-60岁之间的人群，而其余20项研究包括了更多的异质性人群，除了一些60岁以上的人群外，大多数人都在这个目标年龄范围内。在纳入的研究中，嗅觉丧失的病因是神经精神疾病(37%)，特发性原因（25％），2型糖尿病（7%），创伤（5%），感染（4%），智力残疾(4%)，其他（18%）。一些研究报告了许多关联，有时是混合的，导致关联总数大于纳入的54项研究。总的来说,21/54研究表明嗅觉和认知之间存在正相关，7/54证明没有关联，25/54报告了好坏参半的结果，只有1/54显示出负关联。
结论：大多数研究表明OD和认知之间存在正相关，但是与老年人相比，这些数据与年轻人的关联不那么强烈。尽管研究人群和结果存在异质性，这项范围审查是进一步调查这一主题的起点。值得注意的是,由于本综述中的许多研究涉及可能对嗅觉和认知产生混杂影响的疾病，未来的研究应该控制这些混杂因素,并纳入非精神病原因导致嗅觉丧失的非老年人.
方法：我们对PubMed，OvidEmbase,WebofScience,和科克伦图书馆在制定这一范围审查。感兴趣的主要结果是小于60岁的成年人的OD和认知功能之间的关联。
结果：我们确定了2878项研究的标题和摘要综述，167正在进行全文审查，和54选择用于数据提取。其中,34项研究报道了限制在18-60岁之间的人群，而其余20项研究包括了更多的异质性人群，除了一些60岁以上的人群外，大多数人都在这个目标年龄范围内。在纳入的研究中，嗅觉丧失的病因是神经精神疾病(37%)，特发性原因（25％），2型糖尿病（7%），创伤（5%），感染（4%），智力残疾(4%)，其他（18%）。一些研究报告了许多关联，有时是混合的，导致关联总数大于纳入的54项研究。总的来说,21/54研究表明嗅觉和认知之间存在正相关，7/54证明没有关联，25/54报告了好坏参半的结果，只有1/54显示出负关联。
结论：大多数研究表明OD和认知之间存在正相关，但是与老年人相比，这些数据与年轻人的关联不那么强烈。尽管研究人群和结果存在异质性，这项范围审查是进一步调查这一主题的起点。值得注意的是,由于本综述中的许多研究涉及可能对嗅觉和认知产生混杂影响的疾病，未来的研究应该控制这些混杂因素,并纳入非精神病原因导致嗅觉丧失的非老年人.
