One cause of damage in older brains, and how exercise can help

September, 2011

Two mice studies indicate that an increase in a protein involved in immune response may be behind the reduced ability of older brains to create new neurons, and that exercise produces a protein that helps protect against damage caused by illness, injury, surgery and pollutants.

In the first mouse study, when young and old mice were conjoined, allowing blood to flow between the two, the young mice showed a decrease in neurogenesis while the old mice showed an increase. When blood plasma was then taken from old mice and injected into young mice, there was a similar decrease in neurogenesis, and impairments in memory and learning.

Analysis of the concentrations of blood proteins in the conjoined animals revealed the chemokine (a type of cytokine) whose level in the blood showed the biggest change — CCL11, or eotaxin. When this was injected into young mice, they indeed showed a decrease in neurogenesis, and this was reversed once an antibody for the chemokine was injected. Blood levels of CCL11 were found to increase with age in both mice and humans.

The chemokine was a surprise, because to date the only known role of CCL11 is that of attracting immune cells involved in allergy and asthma. It is thought that most likely it doesn’t have a direct effect on neurogenesis, but has its effect through, perhaps, triggering immune cells to produce inflammation.

Exercise is known to at least partially reverse loss of neurogenesis. Exercise has also been shown to produce chemicals that prevent inflammation. Following research showing that exercise after brain injury can help the brain repair itself, another mouse study has found that mice who exercised regularly produced interleukin-6 (a cytokine involved in immune response) in the hippocampus. When the mice were then exposed to a chemical that destroys the hippocampus, the interleukin-6 dampened the harmful inflammatory response, and prevented the loss of function that is usually observed.

One of the actions of interleukin-6 that brings about a reduction in inflammation is to inhibit tumor necrosis factor. Interestingly, I previously reported on a finding that inhibiting tumor necrosis factor in mice decreased cognitive decline that often follows surgery.

This suggests not only that exercise helps protect the brain from the damage caused by inflammation, but also that it might help protect against other damage, such as that caused by environmental toxins, injury, or post-surgical cognitive decline. The curry spice cucurmin, and green tea, are also thought to inhibit tumor necrosis factor.

Reference: 

Related News

A large longitudinal study, comparing physical activity at teenage, age 30, age 50, and late life against cognition of 9,344 women, has revealed that women who are physically active at any point have a lower risk of cognitive impairment in late-life compared to those who are inactive, but teenage

A study involving 733 participants from the Framingham Heart Study Offspring Cohort (average age 60) provides more evidence that excess abdominal fat places otherwise healthy, middle-aged people at greater risk for dementia later in life.

A 12-year study involving 1,221 married couples ages 65 or older (part of the Cache County (Utah) Memory Study) has revealed that husbands or wives who care for spouses with dementia are six times more likely to develop Alzheimer’s themselves than those whose spouses don't have it.

A comprehensive study reveals how the ‘Alzheimer's gene’ (APOE ε4) affects the nature of the disease. It is not simply that those with the gene variant tend to be more impaired (in terms of both memory loss and brain damage) than those without.

A special supplement in the Journal of Alzheimer's Disease focuses on the effects of caffeine on dementia and age-related cognitive decline. Here are the highlights:

Studies on the roundworm C. elegans have revealed that the molecules required for learning and memory are the same from C.

Although research has so far been confined to mouse studies, researchers are optimistic about the promise of histone deacetylase inhibitors in reversing age-related memory loss — both normal decline, and the far more dramatic loss produced by Alzheimer’s.

An implantable cardioverter defibrillator (ICD) is a small electronic device that monitors and regulates heartbeat, and many have been implanted in patients — an estimated 114,000 in the U.S. in 2006.

A 12-year study following the drinking and smoking habits of 22,524 people aged 39-79 has found that in non-smokers, people who consumed moderate amounts of alcohol were 37% less likely to develop stroke than non-drinkers. This association was not found among smokers.

An imaging study reveals why older adults are better at remembering positive events.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news