Catching a cold or the flu, which leads to inflammation in the brain, impairs our ability to form spatial memories. That’s according to researchers from the Brighton and Sussex Medical School (UK) who have been studying how brain chemistry changes with inflammation and the resulting effects on cognition. They say the impairment results from a decrease in glucose metabolism in the brain’s memory centre, disrupting the neural circuits involved in learning and memory.
Inflammation has long been linked to disorders of memory like Alzheimer’s disease. The new findings, published in the journal Biological Psychiatry, help explain why inflammation impairs memory and could spur the development of new drugs targeting the immune system to treat dementia.
For the study, the team scanned 20 participants before and after either a benign salt water injection or typhoid vaccination (used in this case to induce inflammation). Positron emission tomography was then used to measure the effects of inflammation on the consumption of glucose in the brain. After each scan, participants tested their spatial memory by performing a series of tasks in a virtual reality.
Study leader Neil Harrison said a reduction in glucose metabolism within the brain’s memory centre, known as the medial temporal lobe, was seen following inflammation. Participants also performed less well in spatial memory tasks, an effect that appeared to be directly mediated by the change in the medial temporal lobe’s metabolism.
Harrison’s team now plans to investigate the role of inflammation in dementia, including how acute infections such as influenza influence the rate of progression and decline. “Our findings suggest that the brain’s memory circuits are particularly sensitive to inflammation and help clarify the association between inflammation and decline in dementia,” says Harrison. “If we can control levels of inflammation, we may be able to reduce the rate of decline in patients’ cognition.”
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