Patient case (clinical description): A 70-year-old man comes to the office accompanied by his wife.  The patient has experienced progressive memory loss over the last years.  He needs help with some of his routine activities, such as paying bills.  The patient's wife says, "He used to be such an independent person, but now he needs help with many things, even finding direction to home!"  Medical history includes hypertension, hyperlipidemia, and type 2 diabetes mellitus.  Family history includes Alzheimer disease in his father.  MRI reveals diffuse cortical and hippocampal atrophy. The diagnosis of AD is made using the National Institute on Aging and the Alzheimer's Association (NIA-AA) criteria.

Patient's own account: I am a 70-year-old man, and I paid a visit to the doctor with my wife the other day. I noticed that I tend to forget small things and that my memory has decreased over the past few years. I even ask my wife to help me out with my daily routine. I used to be the one paying the bills, but now she has to give me a hand. My wife mentioned to the doctor that I used to be independent and that I tend to forget where we live. I suffer from hypertension, high cholesterol, and type 2 diabetes. My poor dad was suffering from Alzheimer disease, so I hope I'm not going to end the same way! I did an MRI and they found out that some part of my brain was decreasing. I also did an Alzheimer test.

Clinical trial: Cerebral Haemodynamic Changes During Cognitive Testing: A fTCD Study

Eligibility criteria:
Inclusion Criteria:

          -  Informed volunteer consent, patient consent

          -  Male or female, aged between 18 and 100 years of age

          -  Able (in the Investigator's opinion) and willing to comply with all study requirements

          -  Willing to allow his or her General Practitioner (GP) to be notified of participation
             in the study

          -  Good understanding of written and verbal English

        Healthy Controls-specific Inclusion Criteria

          -  No evidence of subjective or objective memory impairment on cognitive testing

          -  No major medical co-morbidity (outlined in detail in the exclusion criteria) or
             medication use that could adversely affect cognition

        MCI Patient-specific Inclusion Criteria

        Clinical diagnosis of MCI made by a specialist* in a patient who fulfils the established
        clinical consensus criteria for MCI [NIA/AA 2011] specifically:

          -  Concern regarding a change in cognition compared to the person's previous level, by
             the patient and/or informant

          -  Objective evidence of impairment of one or more cognitive domains, greater than
             expected for age, and educational background, over time if repeated measures are
             available.

          -  Preserved independence of functional abilities and minimal to no impairment on complex
             instrumental functions

          -  Not demented

        Vascular Dementia Specific Inclusion Criteria

        Clinical diagnosis of VascD made by a specialist* in a patient who fulfils the NINDS-AIREN
        criteria for VascD, specifically:

          -  Cerebrovascular disease defined by the presence of focal signs on neurological
             examination consistent with stroke and evidence of cerebrovascular disease on brain
             imaging.

          -  One or more of:

               -  Onset of dementia within 3 months of a diagnosed stroke

               -  Abrupt deterioration in cognitive function

               -  Fluctuating, stepwise progression of cognitive deficits

        Alzheimer's Dementia Specific Inclusion Criteria

        Clinical Diagnosis of AlzD made by a specialist* in a patient who fulfils the NIA/AA
        criteria for Probable AlzD, specifically:

          -  Meets the criteria for dementia

               -  The memory impairment and cognitive deficits cause significant impairment in
                  social or occupational functioning, and represent a significant decline from a
                  previous level of functioning, not explained by a delirium or a major psychiatric
                  disorder

               -  Impairment of at least two cognitive domains

          -  Insidious or gradual onset

          -  Clear history of worsening cognition by report or observation

          -  The initial and most prominent cognitive deficits are evident on history and
             examination in one of the following domains:

               -  Amnestic: impaired learning and recall of recently learned information

               -  Non amnestic: language/visuospatial/executive dysfunction

          -  No evidence of substantial cerebrovascular disease, core features of dementia with
             lewy bodies, features of frontotemporal dementia, prominent features of semantic
             variant primary progressive aphasia, evidence of active neurological disease, a
             non-neurological co-morbidity or medication that could affect cognition

               -  A specialist being defined as a psychiatrist or a geriatrician, or a specialist
                  mental health nurse with a specific interest or expertise in cognitive disorders.

        Exclusion Criteria:

        Exclusion Criteria

          -  Male or Female, aged under 18 years

          -  Unable (in the Investigator's opinion) or unwilling to comply with any study
             requirements

          -  Female participants who are pregnant, lactating or planning pregnancy during the
             course of the study

          -  Major co-morbidity likely to affect cerebral autoregulation; severe respiratory
             disease, carotid artery stenosis, atrial fibrillation, severe cardiac failure (left
             ventricular ejection fraction <20%), extreme frailty or multi-morbidity.
No condition on gender to be admitted to the trial.
Accepts Healthy Volunteers
Subject must be at least 18 Years old.
Subject must be at most 100 Years

Eligibility (NLI label): Entailment