Identifying predictors of cognitive decline within older age helps to understand its mechanisms and to identify those at greater risk. Here we examine how cognitive change from 11 to 70 years is associated with cognitive change within older age (70 to 82 years) in the Lothian Birth Cohort 1936 longitudinal study (N=1091 at recruitment). Using latent growth curve models, we estimate rates of change from age 70 to 82 in general cognitive ability (g) and in three cognitive domains: visuospatial, memory and processing speed. g accounted for 71.3% of interindividual change variance. Greater 11-70 cognitive gain predicted slower decline in g over 12 subsequent years (β = .163, p = .001), independently of cognitive level in childhood and at age 70, and domain-specific change beyond g. These results contribute toward identifying people at higher risk of age-related cognitive decline.