Changes in brain structure and function are a normal part of the aging process from middle age through older adulthood, yet relatively few studies have focused on healthy aging of brain circuitry and how it varies across people. A better understanding of how typical aging affects the brain is sorely needed, particularly since it would provide a vital baseline for studies of numerous brain disorders whose prevalence increases with age. The AABC (formerly HCP-A) is working to uncover how brain structure and function changes as a normal part of aging by collecting and analyzing multimodal neuroimaging, behavioral, and genetic data. The AABC collected information on 1000+ healthy adults to discover how individual experiences affect ways in which different parts of the brain are connected and how these connections change across healthy adulthood. There were 2 participant populations in the study, healthy young adults ages 22-35 and healthy adults ages 36-100+. Both cross-sectional and longitudinal data was collected relevant to general health including vascular burden, genetic status, diet, physical activity, systemic health, hormonal status, and life history of stress, sleep patterns, social/community engagement, and adversity.

Participants were excluded if there was a lifetime history of neurological disease, brain surgery, major psychiatric disorders, alcoholism/ drug hospitalization, major head injury, epilepsy, brain tumor, undergoing cancer treatments near head or neck, any stage 4 cancer,  brain hemorrhage, brain aneurysm, subdural hematoma or stroke, Long-term use of immunosuppressants, Known genetic disorder such as sickle cell disease or cystic fibrosis, and <80 with macular degeneration diagnosis. Within the last 5 years: pharmacologic or surgical treatment by a neurologist, or endocrinologist for a period of 12 months or longer, except for back pain or thyroid or other condition that is clearly not brain-related or severe depression requiring treatment for over 12 months. Within the last 1 year: diagnosis of thyroid problems and/or changing doses of thyroid medication or heart attack. Other exclusion criteria includes diabetes diagnosed within last 3 months, significant hearing loss that prevents phone communications, vision worse than 20/200, current pregnancy, unsafe metal or devices in the body, moderate to severe claustrophobia, weight greater then 275lbs and/or BMI >35, use of migraine prevention medications, migraine less than 72 hours before 1st visit or during visit, uncontrolled high blood pressure (>170/100), severe lung, liver, kidney, or heart disease or other major organ failure, MOCA ≤19 up to age 79, MOCA ≤17 ages 80-89, MOCA score ≤16 for ages >90, and participants aged 60 to 79, a score of 29 or below on the TICSmec (If participants ages 80 and above score 29 or below on the TICSmec, we give them a secondary screen to determine their eligibility).