That’s because a decrease in glucose metabolism in the brain’s memory center disrupts the neural circuits involved in learning and memory, according to the study, which was published in Biological Psychiatry.
In their experiment, a team at Brighton and Sussex Medical School scanned 20 participants before and after either a benign salt water injection or typhoid vaccination, which was used to induce inflammation.
Positron emission tomography (PET) was used to measure the effects of inflammation on the consumption of glucose in the brain. After each scan, the participants tested their spatial memory by performing a series of tasks in a virtual reality.
A reduction in glucose metabolism within the brain’s memory center, known as the medial temporal lobe (MTL), was seen following inflammation, the scientists reported. Performance on the spatial memory tasks also declined, which appeared to be directly related to the change in MTL metabolism, according to the researchers.
“We have known for some time that severe infections can lead to long-term cognitive impairment in the elderly. Infections are also a common trigger for acute decline in function in patients with dementia and Alzheimer’s disease,” said Dr. Neil Harrison, a Wellcome Trust Intermediate Clinical Fellow at BSMS who led the study.
“This study suggests that catching a cold or the flu, which leads to inflammation in the brain, could impair our memory.”
Infections are unlikely to cause long-term detrimental impact in the young and healthy, but the findings are of great significance in the elderly, he noted.
The 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,” said Harrison. “If we can control levels of inflammation, we may be able to reduce the rate of decline in patients’ cognition.”
Source: Wellcome Trust