Sense of smell tends to decline in individuals with early Alzheimer's disease, typically earlier than when other senses and thinking abilities begin to decline. Memory for new odors is particularly diminished in these individuals. Existing treatments for AD do not improve these symptoms. A targeted treatment for improving sense of smell, called 'Olfactory Training', has been used to improve sense of smell in people with various forms of smell loss, though it is not known whether it can improve smell abilities and thinking abilities in patients who are at high risk of developing Alzheimer's disease. The investigators will conduct a randomized clinical trial with patients who have mild cognitive impairment (MCI). This is an early phase of memory loss that is worse than normal aging and may precede Alzheimer's disease. Patients will be randomized to either olfactory memory training or visual memory training for 3 months, with a final follow-up visit at 6 months. This study will attempt to determine if olfactory training is a useful for improving smell abilities, thinking abilities, and everyday functioning by examining change in these outcomes over time.

There is an urgent and unmet need to develop interventions capable of improving cognition and everyday functioning in individuals at risk for cognitive decline. Olfactory training consists of systematic exposures to odors, with multiple reviews and meta-analyses concluding it has beneficial effects on cognition and olfaction. The application of olfactory training for preventing cognitive decline in MCI has received limited attention. The overarching goal of the research to be carried out in this application is to determine the feasibility and efficacy of Olfactory Memory Training (OMT) for patients with mild cognitive impairment (MCI). 30 patients with MCI will be recruited from the Memory Disorders Center at the New York State Psychiatric Institute and randomized to 3 months of OMT or active control training. OMT will involve an odor memory task, during which patients sample containers consisting of pairs of commercially available odors (flavored tea leaves). During each training session, non-descript containers are placed on a grid. On each trial, patients sample two containers, and attempt to find a match. The active control involves Visual Memory Training (VMT) with matching of abstract symbols rather than odors. Patients will complete 48 training sessions at home lasting approximately 10 minutes each. At baseline, 3 months, and 6 months follow-up, patients will complete a battery of cognitive, olfactory, and functional measures. In Aim 1, the investigators will compare change in cognitive (Preclinical Alzheimer Composite-5 [PACC5]) and olfactory functioning (Sniffin' Sticks Threshold, Discrimination, and Identification [TDI]) over 6 months in OMT versus VMT. In Aim 2, the investigators will compare change in everyday functioning (Alzheimer's Disease Cooperative Study-Activities of Daily Living scale - Prevention Instrument [ADCS-ADL-PI]) over 6 months in OMT versus VMT. If successful, this study has potential to develop a low-cost and scalable intervention. This study will inform the design of subsequent larger trials of OMT.

Inclusion Criteria:

1. Age 55-89 at the time of informed consent.
2. Montreal Cognitive Assessment score >=17.
3. Subjective cognitive complaints, i.e., memory or other cognitive complaints, e.g., naming/language.
4. Meets criteria for cognitive impairment (CI), including either early mild cognitive impairment (eMCI) or late mild cognitive impairment (lMCI), defined as memory function documented by scoring below the education adjusted cutoff on the Logical Memory II subscale (Story A, Delayed Paragraph Recall) from the Wechsler Memory Scale (WMS) - III (the maximum score is 25). The criteria for MCI (includes eMCI and lMCI) are as follows: eMCI is defined by a WMS-III Logical memory delayed recall score of 3-6 with 0-7 years of education, score of 5-9 with 8-15 years of education, and score of 9-11 with 16 or more years of education. lMCI is defined by a WMS-III Logical Memory delayed recall score ≤ 2 with 0-7 years of education, score ≤ 4 with 8-15 years of education, and score ≤ 8 with ≥ 16 years of education.
5. An informant (relative, friend, other caregiver) who contacts the participant at least weekly is required to provide information about the participant's functioning. If the informant drops out, an alternate informant can be designated by the participant.

Exclusion Criteria:

1. Diagnosis of dementia of any type.
2. Neurological disorders including Parkinson's disease, Huntington's disease, multiple sclerosis, stroke, epilepsy, traumatic brain injury (moderate to severe, with greater than 30 min loss of consciousness), and other neurologic disorders with focal signs (e.g., amyotrophic lateral sclerosis).
3. Current clinical diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder, alcohol use disorder, or substance use disorder (Diagnostic and Statistical Manual of Mental Disorders (DSM)-5-Text Revision criteria).
4. Current unstable or untreated major depression, Geriatric Depression Scale (Short Form) score >= 6, or active suicidality based on a suicide scale (Columbia-Suicide Severity Rating Scale Screen version: positive answer to question 1 or 2 followed by item 6 positive answer leads to exclusion. Negative answer to questions 1 and 2: interview ends and the participant is not excluded for active suicidality).
5. Acute, severe unstable medical illness in the judgment of the clinician. For cancer, acutely ill participants (including those with metastases) are excluded, but history of successfully treated cancer does not result in exclusion.
6. Participation concurrently in another therapeutic clinical trial of a cognitive enhancing drug or device or procedure.
7. Current upper respiratory infection (participant rescheduled as soon as this improves), current smoker >1 pack daily (past smoking has been shown not to affect odor identification scores), self-reported congenital anosmia.
8. Severe vision, hearing, or tactile impairment that would prevent the participant from performing the cognitive tests accurately. This will be a clinical determination.
9. History of severe or recent asthma (defined as use of an inhaler for asthma, use of other asthma medication, or occurrence of an asthma attack within the last ten years), known special sensitivities to volatile chemicals, anyone who believes she is pregnant or is nursing a baby, and anyone who is on nasally administered medications other than people on nasal steroids to control rhinitis, allergic and otherwise.
10. Sino-nasal Outcome Test-22 nasal domain score >21, or individual score = 5, representing severe nasal symptoms that interfere with olfaction.
11. Allergies to any odors used in the olfactory testing or olfactory memory training.

The investigators will make de-identified data available to qualified users through a data repository.

The research community will have access to data starting 6 months after the publication of the results that address the Aims of the study.

Due to the pilot nature of the study and fundamental differences between OMT and VMT, neither the participants nor research personnel will be blinded to treatment assignment.