Latent Toxoplasma gondii infection leads to deficits in goal-directed behavior in healthy elderly.

Goal-directed behavior is well-known to show declines in elderly individuals, possibly because of alterations in dopaminergic neural transmission. The dopaminergic system is modulated by a number of other different factors. One of these factors, which has attracted a considerable amount of interest in neurobiology, but has only rarely been examined with respect to its possible modulatory role for cognitive functions in elderly individuals, is latent Toxoplasma gondii (T. gondii) infection. Latent T. gondii infection may be of relevance to goal-directed behavior as it alters dopaminergic neural transmission. We examine goal-directed behavior in T. gondii IgG positive and negative elderly subjects in auditory distraction paradigm. We apply event-related potentials to examine which cognitive subprocesses are affected by latent T. gondii infection on a neurophysiological level. We show that latent T. gondii infection compromises the management of auditory distraction in elderly by specifically delaying processes of attentional allocation and disengagement. The results show that latent T. gondii infection is neglected but an important neurobiological modulator of cognitive functions in elderly individuals.