This is a non-randomized, non-treatment, observational study designed to discover correlations between retinal imaging and amyloid PET imaging. Subjects will be recruited to the clinical cohort from referring physicians. Subjects may be participants from existing studies and clinical practices

Inclusion Criteria:

1. Male and female adults aged 50 to 90 years (inclusive).

2. Individuals with reported cognitive complaint (self or from an informant) under clinical investigation by a health professional for cognitive impairment where Alzheimer's disease (AD) is one of the differential diagnoses.

3. Demonstrated cognitive impairment as evidenced by at least one of the following:

   1. Mini Mental State Examination (MMSE) score < 26/30
   2. Montreal Cognitive Assessment (MoCA) score < 26/30
   3. Score > 1 Standard Deviation below population mean on a standardized neuropsychological test, based on normative data from age-, sex-, education-, and where possible, race-matched peers [Based on guidelines for detecting Mild Cognitive Impairment due to AD (Albert et al., 2011)]

4. Cognitive impairment on the above test/s is unable to be fully explained by systemic, neurological or psychiatric disorders other than Alzheimer's disease.

5. Capacity to give informed consent by patient or Legally Authorized Representative (LAR).

6. Ability to undergo PET and MRI scans.

Exclusion Criteria:

1. Any ophthalmologic condition that would prevent obtaining retinal imaging and/or could interfere with the analysis of the MHRC-C1 images by the CAS, including:

   • Pupil dilation contraindicated (due to a pathology, or presence of 3 quadrants with Van Herick frading of 0 or 1 without iridotomy)

   • Inadequate pupil dilatation (< 6mm diameter) preventing uniform illumination of the retina with the MHRC-C1

   • Diagnosis of glaucoma or signs of glaucoma (excavation ratio ≥0.7)

   • Signs of vascular occlusion or retinopathy (microaneurysm, exudate, hemorrhage or edema) within a diameter of 10 mm from the mid-point between the optic nerve head and the macula

   • Presence of drusen and/or age-related macular degeneration (AREDS 9-step scale

     • 4 - cumulative drusen area diameter ≥ 250 um, pigmentary changes and cumulative drusen area diameter ≥ 63 um or pigmentary changes and cumulative geographic atrophy area diameter ≥ 354 um)

   • Macular anomaly (e.g. macular hole, dystrophy, degeneration)

   • Nuclear sclerosis > 2 (LOCS II four-point grading system) or presence of central cortical or central posterior subcapsular cataract

   • Deficient visual fixation (inability to fixate for at least 2 s)

   • Refractive error outside the range of -15 D to +15 D

   • Corneal or media opacities (e.g. Weiss ring) affecting retinal imaging on a cumulative area > 1 disc area within a diameter of 10 mm from the mid-point between the optic nerve head and the macula (i.e. the area of interest for the MHRC-C1 imaging)

   • Scar, atrophy, naevus, tumor, epiretinal membrane or retinal pucker with a cumulative area > 1 disc area within a diameter of 10 mm from the mid-point between the optic nerve head and the macula

   • Papilledema

2. Inability of obtaining at least 3 images of satisfactory quality with the MHRC-C1 per the Optina Diagnostics quality index software.

3. Impossibility of obtaining a satisfactory quality amyloid-PET scan for interpretation by imaging specialists.

4. Individuals currently enrolled in cerebral amyloid modifying medication studies.

Up to 100 adults between 50 and 90 years old, and undergoing evaluation for Alzheimer's Disease or other cognitive impairments will be recruited from the community. Patients will be asked if they would like to hear about a study related to better diagnostic tools for cognitive decline and dementias, which is seeking volunteers to undergo a non-invasive eye scan with a new type of camera. Informed consent will be obtained prior to enrollment in the study.