An Observational Study Using Multimodal Sensors to Measure Cognitive Health in Adults and Distinguish Mild Cognitive Impairment From Normal Aging

Key Inclusion Criteria: * Fluent in spoken and written English * Minimum 8 years of education or 8th grade equivalent. * Willing to authorize the use of confidential health information in accordance with applicable privacy regulations. * Willing to wear an Apple Watch for daily use for the duration of the study. * Willing to use their personal iPhone for routine daily use for the duration of the study. * Technical requirements: iPhone models: iPhone 8 or newer iOS versions: current publicly available iOS version * Access to one of the following personal computing devices. Microsoft Windows based personal computers (laptops and desktops) Mac personal computers (laptops and desktops) Apple iPad tablets * Access to WiFi or hardwired internet access in participant's place of residence. * Active email address for enrollment account creation and for use in relaying study information. * Active mobile telephone number for use in relaying study information when appropriate. * Primary address within the United States (50 states and Washington, DC; not a post office (PO) box). Key Exclusion Criteria: * Inability to comply with study requirements. * Any self-reported medical history of dementia (such as Alzheimer's disease, frontotemporal dementia, dementia with Lewy body, vascular dementia, rapidly progressive dementia, or Parkinson's disease dementia). * Self-reported dependence on others to perform core activities of daily living, including feeding, dressing, bathing, toileting, or grooming. NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.