The design is an open-ended, prospective, observational, (non-interventional) registry for subjects with mild cognitive impairment (MCI), early symptomatic Alzheimer's disease, Alzheimer's disease, or dementia with clinical suspicion of Alzheimer's disease under the care of a neurologist, psychiatrist, geriatrician or other qualified provider. Longitudinal data are collected from subjects, their care partner(s), and their treating healthcare provider during routine clinical encounters using a structured and standardized data collection method. Approximately 2,000 subjects, with no defined upper limit, across around 75 clinical sites worldwide will be recruited.

The objective of the registry is to create a prospective cohort of Alzheimer's disease subjects to evaluate long-term real-world safety and effectiveness of standard of care treatments for Alzheimer's disease. Data collected through the registry may be used to address a range of research questions and use cases, including but not limited to: Evaluating the effectiveness and safety of commercially available medications for the treatment of Alzheimer's disease, Providing information to support ongoing risk-benefit evaluation by drug manufacturers and regulators, Research related to drug utilization, disease burden, and unmet needs and Supporting post-authorization safety studies to generate evidence related to real world safety of medications used for the treatment of the disease(s) under study

Inclusion Criteria:

To be eligible to participate in this registry, an individual must meet all the following criteria (determined by the investigator):

1. Has been diagnosed with mild cognitive impairment (MCI), early symptomatic Alzheimer's disease, Alzheimer's disease, or dementia with clinical suspicion of Alzheimer's disease.
2. Subject is at least 18 years of age or older and has attained the legal age for consent to procedures involved in the research, under the applicable law of the jurisdiction in which the research is being conducted at the time of enrollment.
3. Has care partner(s) willing to participate as a source of information who maintains regular contact with the subject (defined as at least ten hours per week), will accompany the subject to the clinic visits, has attained the legal age for consent under the applicable law of jurisdiction in which the research is being conducted at the time of consent, and is willing and able to provide informed consent as the care partner.
4. Subject has the ability to understand the purpose, risks, and voluntariness of Registry participation and is willing and able to provide informed consent
5. For US subjects only, must be willing and able to provide Personally Identifiable Information (full legal name, sex at birth, date of birth, home address zip/postal code, and social security number at a minimum).
6. Has been prescribed (and intends to initiate) a commercially available therapy for the treatment of Alzheimer's disease (or symptoms of Alzheimer's disease) (Eligible Medication) at the time of enrollment.

Note: Participation in the registry will not interfere with the standard of care provided by the subject's treating clinician. Investigators retain independent clinical judgment in managing patient care.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in the registry:

1. Is participating or planning to participate in a double-blind randomized clinical trial for a MCI or AD.
2. Has been previously treated with an ATT prior to enrollment into the registry

Subjects enrolled in this registry will be treated according to routine clinical care; treatments are prescribed at the provider's discretion and the decision to treat the subject with a drug is made prior to and independently of study participation. The clinician will determine subject visit schedules according to routine practice, patient needs,and local standard of care (SoC)