Erickson LD, Brown BL, Gale SD, et al. - In animal models and in humans, worsened cognitive function has been reported in correlation with the intracellular protozoal parasite Toxoplasma gondii, so researchers assessed data from the UK Biobank to determine if Toxoplasma gondii is linked with reduced prefrontal, hippocampal, and thalamic gray-matter volumes and with reduced total gray-matter and total white-matter volumes in an adult community-based sample. In adjusted multivariable regression modelling, no correlations were observed between Toxoplasma gondii and prefrontal, hippocampal, and thalamic brain gray-matter volumes. On the other hand, natural-log transformed antibody levels against the Toxoplasma gondii p22 (b = -3960, 95-percent confidence interval, -6536 to -1383) and sag1 (b = -4863, 95-percent confidence interval, –8301 to -1425) antigens were noted to be linked with smaller total gray-matter volume, as was the mean of natural-log transformed p22 and sag1 titers (b = -6141, 95-percent confidence interval, -9886 to -2397). No associations were observed between any of the measures of Toxoplasma gondii and total white-matter volume. In middle-aged and older middle-aged adults in a community-based sample from the United Kingdom, findings indicate a possible correlation between Toxoplasma gondii and reduced total gray-matter.