Effects of flu on brain

Group of researchers from Germany and USA studied effects of influenza virus on brain cells. The study published in the Journal of Neuroscience finds that female mice infected with two different strains of the flu shows changes in structure and function of the hippocampus. These changes persist for one month after infection.

The long-term effect of influenza A virus infection on glial cell density and activation status within the hippocampal subregions. The neurotropic H7N7 IAV infection induced an increased microglia density in all hippocampal subregions at 30 days post-infection. Credit: Hosseini et al., JNeurosci

Influenza could present with neurological symptoms in some cases. So far research has not studied the long-term effect of the virus in the brain.

Researchers investigated three different influenza strains (H1N1, H3N2, H7N7). Two of these strains, H3N2 and H7N7, caused memory impairments that were associated with structural changes such as dendritic spine loss to neurons in the hippocampus. These changes persist up to 30 days following infection and fully recovered in 120 days.

Researchers feel that in the acute phase of influenza infection, this neuroinflammation in hippocampus alters the neuronal morphology and can cause cognitive deficits. The results also provide evidence that neuroinflammation induced by influenza virus infection can lead to longer-lasting alterations in neuronal connectivity with associated impairments in spatial memory formation.

Citation: Hosseini, Shirin, Esther Wilk, Kristin Michaelsen-Preusse, Ingo Gerhauser, Wolfgang Baumgärtner, Robert Geffers, Klaus Schughart, and Martin Korte. “Long-term neuroinflammation induced by influenza A virus infection and the impact on hippocampal neuron morphology and function.” The Journal of Neuroscience, 2018, 1740-17. doi:10.1523/jneurosci.1740-17.2018.

Research funding: Ministry of Science and Culture of Lower Saxony, Helmholtz-Association.

Adapted from press release by the Society for Neuroscience.