Behavioural effects of infectious mononucleosis.

The aim of the present study was to provide preliminary information on the acute and chronic effects of infectious mononucleosis (IM) on memory, attention, psychomotor performance and mood. These issues were examined by comparing individuals with acute IM, those who had the initial illness some months before, and matched healthy controls. Objective measures of memory, attention, motor skills and visual functions were obtained, as were subjective reports of mood. The results showed selective effects of acute IM on performance and mood, with the profile of impairments being very similar to those observed in previous studies of influenza. Different impairments were observed in subjects who had the primary illness several months before, and the effects observed in this group were similar to those observed in recent studies of chronic fatigue syndrome patients. Both acute and chronic IM subjects reported similar levels of symptoms and psychopathology, with both groups having greater scores than the controls. However, the performance impairments did not reflect symptoms or psychopathology. One may conclude that the study of IM will provide important data on both the acute and longer lasting effects of viral infections on the brain and behaviour.