Comprehensive Assessment of Neurodegeneration and Dementia

Inclusion Criteria: * Has subjective or objective cognitive impairment * Written informed consent must be obtained and documented (from the patient or, where jurisdictions allow it, from a caregiver/family member) * Sufficient proficiency in English or French to undertake self report and neuropsychological testing * Geographic accessibility to the study site * Must have a study partner who can participate as required in the protocol (provide corroborative information) * Up to 12 years of education * Fits into one of the following groups: Cognitively Unimpaired, Subjective Cognitive Impairment, Mild Cognitive Impairment, Vascular Mild Cognitive Impairment, Parkinson's Disease, Parkinson's Disease with Mild Cognitive Impairment Exclusion Criteria: * The presence of other significant known chronic brain disease such as: moderate to severe chronic static leukoencephalopathy (including previous traumatic injury), multiple sclerosis, a serious developmental handicap, malignant tumors, Parkinson's disease (other than for the Parkinson's cohort), and other rarer brain illnesses * Ongoing alcohol or drug abuse which in the opinion of the investigator may interfere with the subject's ability to comply with the study procedures * Symptomatic stroke within the previous year * Unable to undergo MRI scan due to medical contraindications or inability to tolerate the procedure