Cross-sectional Study for the Identification of Blood Biomarkers in Healthy Young and Old Individuals

Inclusion Criteria: 1. Men and women between 18 and 25 years (young adults group) or older than 70 for persons at the time of inclusion (old adults group). 2. Subjects with no subjective cognitive complaints. 3. Individuals interested in participating in the study who fully understand all the procedures that will be performed. 4. Explicit participant agreement to undergo all the study procedures, which encompass: 1. Collection of basic demographic data. 2. Collection of a blood sample. 5. Give informed consent and agree that no data resulting from the study (which is no clinically relevant) will be given to the participant Exclusion Criteria: 1. No signs of subjective cognitive impairment. 2. Any significant systemic illness or unstable medical condition which could lead to difficulty complying with the protocol. Including: auditive and visual impairment, renal insufficiency under hemodialysis treatment, hepatic cirrhosis, chronic pneumopathy under oxygen therapy, solid organ transplantation, fibromyalgia, active oncologic disease under treatment (excluding localized tumours). 3. Any significant major psychiatric illness (following DSM-IV diagnosis manual) o diseases that interfere with cognitive function (including major depression disorder, bipolar disorder, schizophrenia). 4. Acquired brain injury: brain traumatic injury with parenchymal or extra-axial macroscopic injury, large vessel ischemic stroke or hemorrhagic stroke, brain tumors or other conditions that may cause acquired brain injury (brain radio- or chemotherapy). 5. Parkinson's disease, epilepsy under treatment and with frequent seizures (\>1 /month) in the last year, multiple sclerosis or any other neurodegenerative disease. 6. Researcher criteria: individuals that have any condition which, under researcher's view, could lead to difficulty complying with the protocol.