Current evidence on older adults is derived from population-based cohort studies and randomized controlled trials, which may not include frail individuals. Data are lacking on older outpatients, a potentially diverse population. Therefore, we initiated the Milan Geriatrics 75+ Cohort Study, a prospective hospital-based outpatient cohort study. Chapter 1 of this thesis provides a background on the controversies regarding the homeostasis of older adults. Chapter 2, 3 and 4 report findings from the Milan Geriatrics 75+ Cohort Study. Chapter 2 explores the association between blood pressure and cognition, and whether it varies according to age and functional status. Chapter 3 examines the relationship between blood pressure and mortality risk, and whether it varies according to functional and cognitive status. Chapter 4 investigates the association between thyroid status and mortality risk in euthyroid older adults, and whether it differs by sex and age. Chapter 5 and 6 report findings from the PROSPER cohort, which includes older adults at high cardiovascular risk. Chapter 5 presents new evidence on the association of heart rate and heart rate variability with functional decline. Chapter 6 analyses the relationship between blood pressure variability and functional decline. Chapter 7 summarises and discusses the main findings of this thesis.UBL - phd migration 201