Alzheimer's Disease

In a new study from the University of Illinois at Chicago, researchers examining post-mortem brain tissue from people ages 79 to 99 find that new neurons continue to form well into old age. The study provides evidence that this occurs even in people with cognitive impairment and Alzheimer’s disease, although neurogenesis is significantly reduce in these people compare to older adults with normal cognitive functioning.

The neural stem cells

The idea that new neurons continue to form into middle age; so let alone past adolescence, is controversial, as previous studies have shown conflicting results. The UIC study is the first to find evidence of significant numbers of neural stem cells and newly developing neurons present in the hippocampal tissue of older adults, including those with disorders that affect the hippocampus, which is involve in the formation of memories and in learning.

They find that there was active neurogenesis in the hippocampus of older adults well into their 90s; so said Orly Lazarov, professor of anatomy and cell biology in the UIC College of Medicine and lead author of the paper. The interesting thing is that we also saw some new neurons in the brains of people with Alzheimer’s disease and cognitive impairment.

She also found that people who score better on measures of cognitive function; so had more newly developing neurons in the hippocampus compare to those who score lower on these tests; hence regardless of levels of brain pathology. Lazarov thinks that lower levels of neurogenesis in the hippocampus are associate with symptoms of cognitive decline and reduce synaptic plasticity rather than with the degree of pathology in the brain.

Hippocampus of older adults

The fact that we found that neural stem cells and new neurons; which are present in the hippocampus of older adults means that if we can find a way to enhance neurogenesis; so through a small molecule, for example; so they may be able to slow or prevent cognitive decline in older adults, especially when it starts; which is when interventions can be most effective,” Lazarov said.

Lazarov and colleagues look at post-mortem hippocampal tissue from 18 people with an average age of 90.6 years. They stain the tissue for neural stem cells and also for newly developing neurons. They find, on average, approximately 2,000 neural progenitor cells per brain.

There’s still a lot we don’t know about the maturation process of new neurons; also the function of neurogenesis in older brains, so it is difficult to predict how much it might ameliorate; so the effects of cognitive decline and Alzheimer’s disease. The more we find out; hence the better able we will be to develop interventions that may help preserve cognitive function even in people without Alzheimer’s. We all lose some cognitive function as their age it’s normal.