Neurology Central

Adult hippocampal neurogenesis reduced in people with Alzheimer’s disease

A research team from the University of Madrid (Madrid, Spain) has recently shown that adult hippocampal neurogenesis (AHN) occurs throughout life and has demonstrated its occurrence in people up to the age of 97. The team also found that the number and maturation of immature neurons in the hippocampus gradually declined as Alzheimer’s disease (AD) advanced. The results of this study have recently been published in Nature Medicine.

Author, Maria Llorens-Martin (University of Madrid) commented: “I believe we would be generating new neurons as long as we need to learn new things. And that occurs during every single second of our life.”

The research team used tissue processing methods to analyze 58 human brain samples obtained from tightly controlled conditions. They found thousands of immature neurons in the denate gyrus in people with neurologically healthy brains.

In people beginning to develop AD there was a progressive decline in the number and maturation of these neurones found, from 30,000 per millimetre to 20,000 per millimetre.

“That’s a 30% reduction in the very first stage of the disease. It’s very surprising for us, it’s even before the accumulation of amyloid beta [a hallmark of Alzheimer’s]and probably before symptoms, it’s very early,” explained Llorens-Martin.

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Rosa Sancho, from Alzheimer’s Research UK (Cambridge, UK), said: “While we start losing nerve cells in early adulthood, this research shows that we can continue to produce new ones even into our 90s.

“Alzheimer’s radically accelerates the rate at which we lose nerve cells and this research provides convincing evidence that it also limits the creation of new nerve cells,” explained Sancho.

The results of the study show the persistence of AHN for the pathological and physiological aging in humans. It also provides evidence for impaired neurogenesis in AD as a possible important mechanism underlying memory deficits, which could lead to the development of novel therapeutic treatment.

Sancho concluded: “Larger studies will need to confirm these findings and explore whether they could pave the way for an early test to flag those most at risk of the disease.”

Source: Moreno-Jimenez EP, Flor- Garcia M, Terreris-Roncal J et al. Adult hippocampal neurogenesis is abundant in neurologically healthy subjects and drops sharply in patients with Alzheimer’s disease. Nat. Med. doi:10.1038/s41591-019-0375-9 (2019) (Epub ahead of print).