Overview
The goal of this clinical trial is to learn whether a new smell test works as well as the standard clinical smell test, if there is a link between sense of smell and variations in the retina, and if these results could be used as a way to identify early stages of Alzheimer's disease. The main questions it aims to answer are:
- Whether the test is as effective and reliable as the standard test
- Whether there is a link between the results of the smell test and the structure of the back of the eye
Participants will:
- complete a short questionnaire
- have pictures of the inside of their eyes taken
- perform two smell tests
Eligibility
Inclusion Criteria:
- Adults who are ≥ 50 and ≤ 80 years of age
- Fluent in English
- Able to provide written consent
- Able to complete a 2.5-3-hour clinical visit, including sitting for spectral domain optical coherence tomography (SD-OCT) imaging for 30 minutes and taking cognitive and olfactory tests for 90-120 minutes
- Cognitive Ability and Family History of Alzheimer's Disease/Mild Cognitive Impairment
(AD/MCI):
- Cohort 1: Cognitively unimpaired, no family history of MCI or AD, and MMSE ≥ 26
- Cohort 2: Cognitively unimpaired, a positive family history of MCI or AD, and MMSE ≥ 26
- Cohort 3: Clinically diagnosed MCI due to AD, and an MMSE score > 22 and ≤ 25
- Cohorts 1 and 2: proficient in independent use of mobile smart devices
Exclusion Criteria:
- A history of significant ocular or nasal trauma that required medical/surgical intervention
- A history of intraocular surgery except cataract extraction
- A cataract extraction within 3 months prior to enrollment
- Diagnosis of visually significant intraocular disease (such as late-stage age-related macular degeneration, glaucoma, or other optic nerve conditions related to brain tumor or multiple sclerosis), drug related vision loss or retinal damage
- Optic neuritis on both eyes
- Current use of medications that may interfere with olfactory functions
- Current use of hydroxychloroquine and tamoxifen, which are known to cause retinal toxicity that may confound OCT interpretation
- A history of recurrent or chronic oto-pharyngeal-laryngeal (ORL) disease (such as chronic rhinitis, nasal polyposis, or sinus disease), head trauma, toxic exposures, upper respiratory infections at time of assessment
- A family history or diagnosis of other neurodegenerative diseases (e.g., multiple sclerosis, Parkinson's disease, Huntington's disease) or conditions that, in the opinion of the Investigators, may affect cognitive or olfactory functions
- Olfactory loss due to COVID (current olfactory loss and/or temporary loss that has been regained)