Acceleration of hippocampal atrophy in a non-demented elderly population: the SNAC-K study.

BACKGROUND Brain atrophy in Alzheimer's disease (AD) includes not only AD-specific brain atrophy but also the atrophy induced by normal aging. Atrophy of the hippocampus has been one diagnostic marker of AD, but it was also found to emerge in healthy adults, along with increasing age. It was reported that the important age when age-related shrinkage of the hippocampus starts was around the mid-40s. The aim is to study the aging atrophy speed and acceleration of brain atrophy in a cross-sectional database, to identify the age at which acceleration of hippocampal atrophy starts in non-demented elderly persons. METHODS 544 subjects (aged 60-97 years; 318 female and 226 male) were recruited into the MRI study by using a subsample of an epidemiological sample of 3363 healthy non-demented elderly people (over 60 years of age). Hippocampus and ventricle sizes were measured. RESULTS The normalized volumes (by intracranial volume, ICV) of the hippocampus in males were smaller than those in females. The right hippocampus was larger than the left. The expansion of the lateral ventricles (2.80% per year in males, 2.95% in females) and third ventricle (1.58% and 2.28%, respectively) was more marked than the hippocampal shrinkage (0.68% and 0.79%, respectively). The suggested age at which acceleration of hippocampal atrophy starts is 72 years. CONCLUSIONS Males present smaller hippocampus volumes (normalized by ICV) than females; however, females are more vulnerable to hippocampal atrophy in a non-demented elderly population. An acceleration of hippocampal atrophy may emerge and start around 72 years of age in a non-demented elderly population.