The immune response to an infection can cause inflammation in the brain, which can affect the functioning of the hippocampus, a brain region involved in memory formation. In addition, certain types of infections can directly affect the brain and cause cognitive impairment.

Research has shown that acute illness, such as a viral infection, can lead to temporary memory impairment. For example, one study found that people with a cold or flu had poorer cognitive performance than healthy individuals, including poorer working memory and processing speed