Effects Of Hydroxytyrosol-Rich Olive Polyphenol Dietary Supplement Combined With Mediterranean Diet Adherence on the Cognitive Health of Patients With Mild Cognitive Impairment.

Nutrition is an important modifiable risk factor of human cognitive health. Increasing data suggests that certain nutrients or food ingredients, such as plant polyphenols, have the potential to benefit cognitive abilities even in later life. In terms of polyphenols, Hydroxytyrosol (HT) has gained health benefit claims as a potential preventative antioxidant supplementation of neurodegenerative and amyloid-associated diseases while its pharmacological mechanisms suggest protection against cognitive decline. The primary objective of this study will be to evaluate the effects of HT-rich olive juice polyphenol supplementation alongside MeDi adherence compared with placebo alongside MeDi adherence in the prevention of cognitive decline among patients with Mild Cognitive Impairment associated with AD and non-AD pathology.

Inclusion Criteria: * GR-based men and women aged 50 - 85 * Willingness and ability to conform to the full protocol. * Ability to accept and sign the consent form. * Presence of a diagnostic classification of Mild Cognitive Impairment according to the National Institute on Aging and Alzheimer's Association (NIA-AA) framework MCI, which corresponds to stage 3 on the pre-dementia range. * MoCA score of ≥18 and ≤ 26. Or * MMSE (Mini-Mental State Examination) score of ≥26 and ≤ 28. * No active suicide ideation based on the Columbia-Suicide Severity Rating Scale. * Absence of severe depressive symptomatology based on the Geriatric Depression Scale-15. * Not using any laxative drugs for at least three days prior to the screening visit. * Information about APOE status Exclusion Criteria: * Patients with mild, moderate, or severe dementia. * Current or recent (within the last 4 weeks) engagement with a strict dietary regime i.e., vegetarian / vegan / ketogenic / paleolithic / high protein / weight loss. * Any known issues with blood taking. * Any known bleeding disorders. * Any known allergy to olives, inability to tolerate gluten or multiple allergies/intolerances that would significantly limit food intake. * Average alcohol use of \>21 glasses per week for men and \>14 glasses per week for women (on average for the last six months). * History of psychiatric illness including intellectual disability, schizophrenia, bipolar disorder, severe, active depression and alcoholism. * Neurologic conditions such as vascular dementia, movement disorders, history of conditions such as anaemia and cancer in the last five years, renal or liver failure, malignant tumours, or organ transplant. * Coffee consumption greater than 5 cups per day. * Body mass index \> 35 kg/ m2. * Not taking a stable dose of statins for at least 3 months before the recruitment visit. Taking antibiotics in the 1 week preceding the recruitment visit. * Pregnancy or lactation. * Participation in another clinical trial during the last 30 days prior to the recruitment visit. * Subject taking supplements that may affect lipoprotein metabolism, \>1 g of fish oil/day, antioxidant supplements, cannabidiol (CBD) oil.