Look after your T-cells (Image: Science Faction/Getty)
Read more: “Infectious moods: How bugs control your mind”
The decline in our memories in old age could be partly due to the ageing of immune cells, opening up new prospects for treatments
Could boosting the immune system keep your memory sharp as you age? Jonathan Kipnis of the University of Virginia in Charlottesville thinks so.
Prompted by studies suggesting immune responses can help repair the nervous system, Kipnis and his colleagues created mice that lack CD4 cells, a kind of T-cell. They found the mice performed extremely poorly in tasks involving learning and memory, but when they were injected with CD4 cells from healthy mice, their memories improved (Proceedings of the National Academy of Sciences, vol 101, p 8180). Similarly, when he killed CD4 cells in healthy mice, their memory declined.
Further animal studies by Kipnis and others show that learning new tasks triggers a mild stress response within the brain, which prompts CD4 cells to rally to the meninges, the membranes that surround the brain. Here, they release IL-4, which both switches off the stress response and tells brain cells called astrocytes to release brain-derived neurotrophic factor, a protein that enhances learning (Journal of Experimental Medicine, vol 207, p 1067).
Whether these animal studies are relevant to human learning and memory remains unclear, but there is some indirect evidence to support it. For example, many chemotherapy drugs suppress the immune system, which might explain why some people with cancer develop “chemobrain” – a term used to describe the cognitive problems and memory loss associated with chemotherapy.
Sluggish immune cells might…
