Restoring production of hippocampal neurons in old age

The production of hippocampal granule neurons continues throughout adulthoo d but dramatically decreases in old age. Here we show that reducing cortico steroid levels in aged rats restored the rate of cell proliferation, result ing in increased numbers of new granule neurons. This result indicates that the neuronal precursor population in the dentate gyrus remains stable into old age, but that neurogenesis is normally slowed by high levels of cortic osteroids. The findings further suggest that decreased neurogenesis may con tribute to age-related memory deficits associated with high corticosteroids , and that these deficits may be reversible.