This study aims to develop and validate a sensitive and non-invasive eye-tracking software application.

This study will obtain participant responses to brief cognitive tests designed to evaluate several key functions known to be affected by Alzheimer's Disease and non-invasive eye movement measurements in response to visually presented stimuli during specifically designed eye-tracking tests. The study data will be used to develop machine learning algorithms and validate a software application intended to track the progressive component of Alzheimer's Disease and associated cognitive changes.

Inclusion Criteria:

• For all participants:

  1. Able to provide informed consent
  2. Aged 18 years or older at the time of enrollment
  3. Able to read in either French or English
  4. Visual acuity of 20/100 in at least one eye (corrective glasses, contact lenses, surgery etc. are permitted)

• For patients only:

  1. Confirmed diagnosis of AD based on the NIAAA diagnostic criteria of probable AD
  2. Having undergone a full neuropsychological evaluation within the last 6 months or having a planned full neuropsychological evaluation within the next 6 months.
  3. AD diagnoses supported by FDG-PET scan or amyloid biomarkers (CSF or amyloid PET)

Exclusion Criteria:

• For AD participants:

  1. Diagnosed with one of the following dementia subtypes: Fronto-temporal dementia, Lewy-body dementia, or Creutzfeldt-Jakob disease.
  2. Incapacity to provide informed consent or inability to adequately understand the task instructions.

• For all participants:

  1. Evidence or medical history of psychiatric issues, which are known to also affect movements and oculomotor control.
  2. Presence of comorbid neurological conditions to avoid eye movement anomaly confounds (strabismus, cranial nerve palsy, stroke-causing hemianopsia).
  3. Diagnosis of macular edema or other pre-existing ocular conditions (e.g., glaucoma, cataracts) that would prevent from performing the eye movement assessments.
  4. Unstable medication use: recent (less than one month from enrollment) start of, change of dose, or irregular use of, new prescription drugs known to have an effect on ocular motor visual function, such as benzodiazepines, antipsychotics and anticonvulsants. Occasional use of benzodiazepines for medical procedures is permitted, at the investigator's discretion, but should not occur within a short time period of an eye movement assessment.
  5. Diagnosed with an active substance use disorder.
  6. History of stroke.
  7. Recent traumatic brain injury (within the last 6 months).

• For healthy controls only:

  1. Evidence or history of significant neurodegenerative disorder affecting brain function (e.g., MS, PD, ALS, Non-AD Dementia)

For this study, we will recruit 250 participants. 200 will be AD patients (including predominant AD with mixed vascular and MCI due to AD), who will subsequently be divided into 4 sub-groups of 50 based on their CDR score (questionable/very mild dementia (CDR = 0.5), mild dementia/MCI (CDR = 1), moderate dementia (CDR = 2), and severe dementia (CDR = 3)), and 50 will be healthy cognitively intact age-matched control participants.