BackgroundPopulation aging will be one of humanity’s major challenges in the decades to come. In addition to focusing on the pathologies causing the greatest mortality and morbidity in this population, such as dementia, health research in elderly people must consider a myriad of other interlinked factors, such as geriatric syndromes, social aspects, and factors related to preserving quality of life and promoting healthy aging. This study aims to identify the main subject areas attracting research attention with regard to very old (≥ 80 years) populations.MethodsDocuments assigned with the medical subject heading “Aged, 80 and over” were retrieved from MEDLINE and the Web of Science. This dataset was used to determine publication output by disease, geographic region, country, and discipline. A co-word analysis was undertaken to identify thematic research clusters.ResultsSince the mid-2000s, there has been a boom in scientific output focusing specifically on very old populations, especially in Europe (43.7% of the documents) but also in North America (30.5%) and Asia (26%); other regions made only nominal contributions (0.5 to 4.4%). The USA produced the most research, while the most growth over the study period occurred in Japan, Spain, and China. Four broad thematic clusters were identified: a) geriatric diseases, health services for the aged, and social and psychological issues of aging; b) cardiovascular diseases; c) neoplasms, and d) bacterial infections & anti-bacterial agents.ConclusionsScientific research in very old populations covers a wide variety of interrelated topics. In quantitative terms, the top subject areas have to do with cardiovascular and cerebrovascular diseases (including aortic valve stenosis and stroke), dementia, and neoplasms. However, other degenerative pathologies, geriatric syndromes, and different social and psychosocial aspects also attract considerable interest. It is necessary to promote more equal participation in global research on pathologies and topics related to very elderly populations, as the highest rates of population aging and the largest numbers of elderly people in the next decades will be in low- and middle-income countries.