title: What is aging? Highlights of a 25-year study.
mesh_terms: D000223:Adaptation, Psychological; D000328:Adult; D000368:Aged; D000375:Aging; D000818:Animals; D006321:Heart / Q000502:physiology; D006801:Humans; D007109:Immunity; D008137:Longitudinal Studies; D008606:Mental Processes; D008875:Middle Aged; D010551:Personality; D051381:Rats; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology