The researchers at Lorestan University of Medical Sciences, Iran, infected mice with the parasite Toxoplasma gondii, others were injected with a toxic version of the amyloid protein and a third group was given both. Mice that were infected with Toxoplama gondii alone appeared to have impaired learning and memory skills. Mice that received doses of both the parasite and amyloid protein appeared to have an increased likelihood of developing Alzheimer’s disease.
Toxoplasma gondii is commonly found in cats, and around one third of people are thought to be infected worldwide. Infection is commonly passed on through handling contaminated cat litter. Once infected, the parasite moves to the brain and can cause symptoms can sometimes produce behavioral changes that mimic schizophrenia.
Commenting on the research, Dr Doug Brown, Director of Research and Development at Alzheimer’s Society, said:
‘While there have been some studies looking Toxoplasma gondii infection and risk of Alzheimer’s disease, the results have been contradictory. While this research suggested that Toxoplasma infection can affect memory and learning in mice, there is no evidence that this is the same for people. When looking for links between infections and dementia, it can be very difficult to separate cause from effect – we can’t say whether the parasite leads to disease development, or if dementia increases vulnerability to infection.’
‘While it’s always a good idea to wash your hands after petting animals, there’s no known link between any infection and Alzheimer’s disease.’