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 on the body composition measured by DXA scans (MAPT-DXA)

This is a multi-centre , randomised, placebo-controlled study in parallel groups in 1680 frail elderly subjects over the age of 70 years, living at home, monitored for a period of 3 years. The subjects will be randomised into one of the following 4 groups:

• Omega-3 group: 800 mg/day of docosahexaenoic acid (V0137CA nutritional supplement)
• Omega-3 + multi-domain intervention group: 800 mg/day of docosahexaenoic acid ( V0137CA)
• Placebo + multi-domain intervention group
• Placebo group The multi-domain intervention includes training / information sessions in the following 4 areas: nutrition, physical activity, cognitive training and social activities, and preventive consultations.

Selected subjects will present at least one of the following frailty criteria:

• Loss of one Instrumental Activity Daily Living (IADL)
• Subjective memory complaints to a physician
• Slow walking speed. Follow-up visits will occur every six months for 3 years for both dispensing of supplement and compliance (months 6, 12, 18, 24, 30 and 36) and neuropsychological and functional assessment (months 6, 12, 24, 36).

Inclusion Criteria:

• subjects of both sex, aged of 70 years or over,
• subjects with at least one of the following frailty criteria: a subjective memory complaint, expressed to their attending physician, an inability to perform one of instrumental activities of daily living, a slow walking with a speed ≤ 0.77 m/s, i.e 5 seconds to walk 4 meters.
• subjects with an MMSE score of greater than or equal to 24,
• subjects capable of understanding the protocol, complying with its requirements and attending the study visits,
• subjects with sufficient availability to take part in the multi-domain intervention programme,
• subjects who, in the opinion of the investigator, are liable to comply with the treatment during the study;
• subjects capable of giving their written informed consent
• Covered by a health insurance system

Exclusion Criteria:

• Criteria related to diseases:

  • known presence of dementia or Alzheimer's disease (DSM IV criteria),
  • deterioration in global cognitive function (MMSE < 24),
  • dependency for basic activities of daily living (ADL<6),
  • presence of serious diseases, which could be life-threatening in the short term,
  • history or presence of any disease that could compromise the subject's participation in the multi-domain intervention sessions,

• Criteria related to treatments:

  o taking of supplements containing omega-3 (apart from food) within the past 6 months and/or taking omega-3 at inclusion.

• Criteria related to subjects:

  • visual or hearing impairments incompatible with performance and/or interpretation of the neuropsychological tests,
  • history or presence of any previous pathologies that could, in the opinion of the investigator, interfere with the results of the study or expose the subject to an additional risk,
  • subjects deprived of their freedom by administrative or judicial decision, or under guardianship or admitted to a healthcare or social institution,
  • participation in another clinical study in the previous month or participation scheduled during the study.