Use it and still lose it? The association between activity and cognitive performance established using latent growth techniques in a community sample

The idea that activity, both physical and mental, may be a protective factor against cognitive decline in later life has enjoyed currency in both the popular and general medical literature. However, considerable uncertainty remains about the relationship between activity and cognitive performance due to differing definitions of activity and to the use of select samples. The current report analysed data from a probability sample of 887 participants recruited from the community, aged 70-93 years in 1991 and followed up in 1994 and 1998. Activity was assessed using a six-item scale comprising activities that are both commonly undertaken and relevant to old age. Latent growth curves were fitted to longitudinal outcomes including activity, cognitive performance and health measures. Reduction in activity over the course of the study was observed in most participants. Substantial correlations between rates of change in activity and cognitive and health measures were observed. Decline in cognitive performance was also observed in a sub-sample of participants who maintained activity over the three waves of measurement. It was concluded that decline in mental and physical activity in older age is paralleled by decline in cognitive functioning and health. The results do not preclude the possibility that introduced modifications in activity might change the course of cognitive performance later in the life span. Further research is required to establish the causal nature of the relationship between activity and cognition.