Age-related dendritic growth in dentate gyrus of human brain is followed by regression in the 'oldest old'.

Dendritic extent in dentate gyrus granule cells of normal aging human brain was found to increase between middle age (fifties) and early old age (seventies). However, dendritic regression was found in the oldest old (nineties). This finding of dendritic regression following growth is in contrast to previous quantitative reports of continued dendritic growth in parahippocampal gyrus of aging human brain. This new result reinforces the concept of age and region specificity in changes in dendritic extent.