Omega-3 Fatty Acids and/or Multi-domain Intervention in the Prevention of Age-related Cognitive Decline

Epidemiological and fundamental research carried out in recent years has highlighted the role played by omega-3 fatty acids in the process of cognitive decline that accompanies advancing age and Alzheimer's disease. In addition, it has been recognized for some years, following several convergent studies on the prevention of cognitive decline, that nutrition, physical exercise, cognitive training and social activities play a significant role in the maintenance of cognitive faculties. At present, there are a number of epidemiological arguments in favour of a protective role of each of these factors taken in isolation. It can be postulated that a multi-domain intervention may potentiate the protective role of omega-3 fatty acids. The main objective of this study is to assess the efficacy of isolated supplementation with omega-3 fatty acid, an isolated multi-domain intervention (nutrition, physical exercise, cognitive stimulation, social activities), or their combination on the change of cognitive functions in frail elderly subjects aged of 70 years and older over 3 years. Secondary objectives: * To assess the efficacy of each treatment strategy on the change of functional capacities and the prevention of dependency, * To study the long-term safety and tolerability of V0137, * To study compliance and adhesion to the multi-domain intervention programme, Ancillary studies : To assess the impact of an intervention program on brain metabolism in FDG PET (MAPT-NI : : impact of multidomain intervention on brain metabolism (FDG-PET)) * To evaluate the impact of preventive strategies (Omega-3 treatment and multidomain intervention ) of MAPT study on brain atrophy (MRI), * To evaluate the presence and density of ß-amyloid in MAPT subjects using AV45 PET scans (MAPT AV45), * To determine if sleep disorders at early stage of Alzheimer 's disease could be predictive of cognitive decline and used as diagnosis tools (Mapt SLEEP) * To evaluate the impact of omega-3 fatty acids o