The parasite Toxoplasma gondii has some favorable effects on the pathogenesis and progression of a mouse model of Alzheimer\'s disease, reports a study in the open access journal PLoS ONE. Toxoplasma gondii, a parasite commonly hosted in cats and generally known for the potential complications it can cause for human pregnancies, suppressed the immune system. The researchers behind this study, led by Eun-Hee Shin of the Seoul National University College of Medicine, found that this immune system suppression had positive effects on Alzheimer\'s disease mouse models, resulting in a significant decrease in the amount of b-amyloid plaque deposition, a hallmark of Alzheimer\'s disease, and better performance in behavior tests like a water maze.