Relationship between cognitive impairment and olfactory function among older adults with olfactory impairment

The Association between Olfactory Function and Cognitive Impairment in Older Persons with Cognitive Impairments: A Cross-Sectional Study

“…An important result of this study is the relationship between olfactory function and cognitive impairment. Although several previous studies report a relationship between olfactory function and cognitive impairment [7][8][9][10][11]21,30], to the best of our knowledge there are no studies that confirm the relationship between olfactory function and detailed areas of cognitive function. Therefore, we identified the relationship between olfactory function and cognitive impairment based on the UPSIT tool, which assesses olfactory identification function, and the expanded CDR, which is a tool for distinguishing overall cognitive function level.…”

“…Age is generally the most important variable affecting olfactory and cognitive function [6]. Many recent studies have demonstrated that cognitive impairment in older persons is accompanied by a decrease in olfactory function [7][8][9][10][11]. Therefore, in this study, it is considered a natural result that reduced olfactory function and cognitive impairment were more common among participants over 75 years of age than those who were younger.…”

“…Several previous studies have demonstrated that cognitive impairment in older persons is related to general characteristics such as age, sex, and education [2], lifestyle factors such as drinking and smoking [3], and disease factors such as diabetes [4] and depression [5]. In recent years, many researchers have become increasingly interested in studies on the olfactory impairment observed in the early stages of neurodegenerative diseases, such as Alzheimer's disease (AD), and Parkinson's disease (PD), and cognitive impairment [6][7][8][9][10][11].…”

The Olfactory System as Marker of Neurodegeneration in Aging, Neurological and Neuropsychiatric Disorders

“…Declining olfactory acuity and olfactory dysfunction ranging from subtle to severe have now become a well-established feature of the normal aging process [ 28 , 29 , 30 , 31 , 32 ]. These are detectable in an age-dependent manner: in 50% of tested subjects ranging from 65 to 80 years in age, while increasing to 75% of those who are above 80 years [ 8 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”

“…Declining olfactory acuity and olfactory dysfunction ranging from subtle to severe have now become a well-established feature of the normal aging process [ 28 , 29 , 30 , 31 , 32 ]. These are detectable in an age-dependent manner: in 50% of tested subjects ranging from 65 to 80 years in age, while increasing to 75% of those who are above 80 years [ 8 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Age-associated ossification and closure of foramina of the cribriform plate [ 34 , 36 ], as well as quantitative reduction of the olfactory epithelium and its replacement by respiratory epithelium [ 37 ], are anatomical and histological factors leading to olfactory decline and dysfunction.…”