The adult hippocampal neuralgenesis in healthy subjects is high, but it drops dramatically in Alzheimer’s patients
The hippocampus has been shown to be one of the areas most affected by Alzheimer’s (AD). This structure is also home to one of the most remarkable phenomena in the adult mammalian mind, which is the addition of neurons over the course of life. This process is called adult hippocampal Neurogenesis (AHN), and it confers an unprecedented degree of plasticity on the entire hippocampal system3,4. Despite this, there is no direct evidence that AHN occurs in humans. Determining whether new neurons are continually incorporated into human dentate gyrus during physiological and disease-related aging is a critical question that has outstanding therapeutic potential. We identified thousands of immature neuronal cells in the DGs of neurologically-healthy human subjects, up to their ninth decade of age, by combining brain samples collected under controlled conditions with state-of-the art tissue processing techniques. The neurons showed varying degrees of maturity along the differentiation stages of AHN. The number and maturity of these neurons decreased as AD progressed. These results show that AHN persists during physiological and pathological aging and suggest that impaired neurogenesis may be a relevant mechanism underlying the memory deficits associated with AD.