Cohort Profile: The Community-based Cohort of Functional Decline in Subjective Cognitive Complaint elderly study of the Geroscience Center for Brain Health and Metabolisms (GERO)

Background: Dementia worldwide is one of the most important causes of disability in the elderly and the most rapidly growing cause of death in the last 20 years in Chile. Cognitive complaint is considered a predictor for cognitive and functional decline (FD), incident mild cognitive impairment, and incident dementia. The GERO cohort aims to determine multidimensional risks factors associated with the prognosis of elderly with cognitive complaint on DF. Method: The GERO cohort is a prospective cohort study of community-dwelling elderly with cognitive complaint, without dementia, aged 70 or older living in 4 municipalities in Santiago, Chile. Participants were identified by a household census and information on demographics, biomedical, psychosocial, neuropsychological, neuropsychiatric, and motor function were collected by means of questionnaires and evaluations. Neuroimaging, blood, and stool samples were also obtained. FD was measured by the Pfeffer (score range 0-33), Technology Activities of Daily Living Questionnaire (T-ADLQ, score range 0-100), and Everyday Cognition (ECOG, score range 0-36) questionnaires. Result: A total of 17,759 households were successfully approached, identifying 2,533 eligible subjects, accepting to participate 299 (59 men; 240 women). The mean age was 76.8±5.1, 25% older than 79. The average years of schooling was 8.9± 4.8. None of participants showed underweight. The average score for the Mini-mental State Exam (MMSE) was 27.1± 2.4, with 5.3% of the sample scoring less than 23. The mean values for Pfeffer, T-ADLQ, and ECOG were 0.8±1.3, were 11.9± 10.3, and 0.4±0.4 respectively. In the multivariate analysis MMSE was inversely correlated with the ECOG score (regression coefficient: -0.03 [95%CI -0.07; -0.002]. Pfeffer also was associated, but its statistical significance was lost after the multivariate adjustment. Conclusion: Few other studies addressed cognitive complaint and functionality in elderly recruited at home. Elderly in the GERO-cohort with cognitive complaint, without dementia, show a good level of functioning at the first assessment. Cognitive function measured by the MMSE seems to be associated to a subtle decline in general functioning as everyday cognition. Future multidimensional and prospective analysis of this cohort could bring more information about this association.