Age-related cortical thinning in cognitively healthy individuals in their 60s: the PATH Through Life study.

Although it is recognized that the human cortex thins with age, longitudinal estimates of thinning patterns specific to healthy young-old age (<75 years) individuals are lacking. Importantly, many neurodegenerative disorders first manifest between midlife and old age, and normative estimates may provide a reference for differential change associated with such disorders. Here, we provide longitudinal estimates of cortical thinning observed over 12 years in a large group (n = 396) of healthy individuals, aged 60-66 years at baseline scan, who were scanned with magnetic resonance imaging (1.5T) on 4 occasions. Longitudinal age-related thinning was observed across most of the cortices, with a mean change of -0.3% per year. We measured significant thinning in heteromodal association cortex, with less thinning in regions expected to atrophy later in life (e.g., primary sensory cortex). Men showed more extensive thinning than women. Our comparison of cross-sectional and longitudinal estimates adds to growing evidence that cross-sectional designs may underestimate age-related changes in cortical thickness.