Poster Session 06 Program Schedule
02/15/2024
04:00 pm - 05:15 pm
Room: Majestic Complex (Posters 61-120)
Poster Session 06: Aging | MCI | Neurodegenerative Disease - PART 2
Final Abstract #68
Association Between Olfactory Dysfunction and Neurodegenerative Disease Progression: a Systematic Review
Yumiko Baba, Aoba-Japan International School, Bunkyo, Japan
Paul Lewis, Columbia University Vagelos College of Physicians and Surgeons, New York, United States
Category: Neurodegenerative Disorders
Keyword 1: olfaction
Keyword 2: Parkinson's disease
Objective:
Associations between olfactory dysfunction (OD) and neurodegenerative disease (ND) have been widely reported. This systematic review aims to characterize the relationship in the setting of Alzheimer’s disease (AD) and Parkinson’s disease (PD).
Participants and Methods:
A systematic review was conducted following PRISMA guidelines using predetermined search terms, such as “olfactory dysfunction” and “anosmia” as well as “Parkinson” and “Alzheimer” on PubMed, PsycInfo, and Cochrane. A total of 2331 articles were found on AD (n=1505) and PD (n=826). These results were narrowed based on title and abstract, which yielded 52 articles to be screened. From the studies screened, 31 articles were excluded due to subjects (non-human animal models), credibility (not peer-reviewed), language (other than English), and relevance (not a result or analysis of the article), leaving 21 papers for the final synthesis (AD n=5; PD n=16).
Results:
Associations between OD and ND were present in the analyzed studies. Across the included studies involving both PD (n=262) and healthy controls (HC, n=244), OD was strongly associated with PD (OR 10.6, LR+3.73, CI 2.85-4.87), and a positive correlation was found between the Sniffin’ Sticks Test and the Mini Mental Status Exam (p=0.047) specifically with orientation (p=0.041) and language (p=0.003). While average University of Pennsylvania Smell Identification Test (UPSIT) scores were lower in PD patients (21.2, SD=6.7) compared to healthy controls (32.8, SD=4.3), motor function and disease duration were not associated with OD. In AD patients, a positive correlation was found between the San Diego Odor Identification Test (SDOIT) and the Boston Naming Test, with 27% and 77% correct in AD patients, and 62% and 96% in HC, respectively. Studies found that the identification of certain odors were significantly lower in AD such as grape (p=0.025) and chocolate (p=0.029) and in PD such as banana (p<0.0001), dill pickle (p<0.0001), and licorice (p<0.0001) compared to HC.
Neuronal and tissue atrophy related to AD and PD in the brain were also associated with OD. PD patients who had a more severe OD underwent a greater reduction in the volume of basal ganglia, olfactory bulb, orbitofrontal cortex, and striatal regions than HC. In PD, OD was positively correlated with markers for brain reserve (intracerebral volume, p=0.037; and gray matter volume, p=0.007). AD patients who had lower SDOIT scores had reduced left hippocampus and gray matter volume in the medial temporal lobe. An apolipoprotein E (APOE)-e4 gene was negatively correlated with cerebrospinal fluid Aß protein levels, though APOE-e4 carriers and non-carriers showed no group difference in odor identification (p=0.271). Patient quality of life was also affected by OD.
Conclusions:
Overall, OD was associated with structural and clinical differences in both PD and AD. Further examining OD in ND may provide a more accurate understanding of the disease course and another method for clinical diagnosis and goals of care plans.
| 
