Cortical Thinning at Midlife: The PATH Through Life Study.

Cortical thinning is a part of normal ageing. Recent studies suggest that accelerated cortical thinning in vulnerable regions may be a useful biomarker for neuropathologies including Alzheimer's disease (AD). Longitudinal studies, which have largely focused on older adults, have provided estimates of normative rates and patterns of age-related cortical thinning. Very little, however, is known about healthy cortical thinning at midlife. Here we provide longitudinal estimates of age-related cortical thinning observed over 8 years, in a large (n = 404) group of healthy individuals aged 44-49 years at baseline, who were scanned with MRI (1.5T) on up to three occasions. Age-related cortical thinning was assessed across the whole cortex. We measured a mean annual decrease in cortical thickness of 0.26 % on the left and 0.17 % on the right hemisphere, and largely affecting frontal and cingulate cortices. Medial and lateral temporal regions were generally spared. Studying regions that are specifically vulnerable to-or spared from-healthy age-related cortical thinning at midlife may be important for the early identification of neurodegeneration, including AD.