Review article
The influenza infection and cognitive functions

Influenza is a seasonal viral disease. Every year 5-25% of the world’s population suffers from influenza and up to 1 mln people die. In Poland several thousand to several million cases and suspected cases of influenza are registered every epidemic season. According to WHO, respiratory viruses are pathogens that infect people most frequently. Epidemiological studies have indicated a link between influenza type A infection (subtype H3N2 and H1N1), type B infection and cognitive functions impairment (mainly declarative memory, attention, visual-movement coordination), neurodegenerative diseases, neurological symptoms and certain psychiatric diseases (e.g. schizophrenia). Both acute and chronic systemic inflammation are characterized by the systemic production of the proinflammatory cytokines in the brain: tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-2 and IL-6. Higher peripheral levels of inflammation are associated with activation of central inflammatory mechanisms that result in hippocampal neurodegeneration. The aim of the study is to describe present research about impact of influenza infection on cognitive functions. The authors are aware of the lack of empirical data confirming connections between inflammation and cognitive functions but they would like to try present this approach.