Cerebral Haemodynamic Changes During Cognitive Testing: A fTCD Study

850,000 people live with dementia in the UK, with that number expected to rise to more than 1 million within the next 5 years. The most common type of dementia (55%) is Alzheimer's dementia, and vascular dementia is the second commonest type (15%). Mild cognitive impairment (MCI) affects up to 20% of older adults and describes a set of symptoms rather than a specific medical condition or disease. A person with MCI has subtle problems with one or more of the following: day-to-day memory, concentrating, planning or organising, language (eg struggling to find the right word), and judging distances and seeing objects properly. Although MCI significantly increases the risk of developing dementia (by up to 5 times), at present it is not possible to accurately predict which patients with MCI will progress to dementia. In recent times there has been an increasing awareness that problems with brain blood flow may contribute to the development, or progression, of dementia. Tests of mental abilities, with standardised questions and pen-and-paper tests are a key component of the formal diagnosis of dementia, yet little is known of the effects of these tests on brain blood flow. Brain blood flow can be can be assessed non-invasively by the use of Trans Cranial Doppler (TCD). This means using ultrasound probes over both sides of the head to measure changes in blood flow in one of the main brain arteries (the middle cerebral artery). This proposed study will therefore use TCD to evaluate changes in brain blood flow during performance of the Addenbrooke's-III (ACE-III) cognitive assessment in four key groups of patients, specifically: 1. Healthy older adults 2. Patients with mild cognitive impairment (MCI) 3. Patients with vascular dementia 4. Patients with Alzheimer's dementia