Identification of Epigenetic Markers Common to Obesity and Alzheimer's Disease in Women

Inclusion Criteria: Group 1: * 18-50 year old women, age- (10 years) and sociocultural-matched with group 2 * Non obese and never been obese * 18.5 \< BMI \< 25 * Folstein MMS \> 27 * Informed consent * Affiliation to social security plan Group 2: * 18-50 year old women, age- (10 years) and sociocultural-matched with group 1 * Waist size \> 88cm * 30 \< BMI \< 45 * Insulin-resistant patients (Insulin resistance index, HOMA-IR \> 3.8) * Obesity onset during childhood (pre-puberty period) * Folstein MMS \> 27 * Informed consent * Affiliation to social security plan Group 3: * \>60 year old women, age- (10 years) matched with group 4 * No obesity history (18.5 ≤ BMI \< 25 at adult age) * Sporadic forms of mild to moderate AD with demonstration of AD physiopathologic process according to new recommendations of 2011 of National Institute on Aging and Alzheimer's Association on diagnostic guidelines for Alzheimer's disease * 15\< Folstein MMS ≤ 26 * Informed consent * Affiliation to social security plan Group 4: * \>60 year old women, age- (10 years) matched with group 3 * Obesity history (BMI \> 30 at least one time at adult age) * Sporadic forms of mild to moderate AD with demonstration of AD physiopathologic process according to new recommendations of 2011 of National Institute on Aging and Alzheimer's Association on diagnostic guidelines for Alzheimer's disease * 15 \< Folstein MMS ≤ 26 * Informed consent * Affiliation to social security plan Exclusion Criteria: Group 1: * \<18 * Patient under guardianship, curatorship or judicial protection * Folate supplementation * Diabetic or glucose intolerant subjects * Present participation to another study with neuropsychological evaluation and/or drug administration * Pregnant women Groups 2,3 and 4: * \<18 * Patient under guardianship, curatorship or judicial protection * Folate supplementation * Present participation to another study with neuropsychological evaluation and/or drug administration Group 2: \- Pregnant women Group 4: \- Obese or overweight patients (BMI\>25)