Brain Parasite Implicated in Neurological Disorders

May 3, 2012 § Leave a comment

A research team from the University of Leeds discovered that Toxoplasma gondii, an infection-causing brain parasite, was found in 10-20% of the UK population. This infection directly affects the production of dopamine, which is a key chemical messenger in the brain. Their findings were the first to demonstrate that the loss of dopamine levels in mammals could be due to a parasitic infection.

Although the research has largely been conducted with rodent subjects, Dr. Glenn McConkey of the University’s Faculty of Biological Science, believes that the team’s findings could shed new light on human dopamine-related neurological disorders. These types of disorders include Schizophrenia, Attention Deficit Hyperactivity Disorder (ADHD), and Parkinson’s disease.

The research performed using rodents shows how, remarkably, the parasites manipulate their host’s behaviour to their own advantage. For example, while infected with the parasite, mice and rats lose their fear of cats, allowing themselves to be more easily caught and eaten. This allows the parasites to return to their main host, to complete their life cycle.

Funded by the Stanley Medical Research Institute and Dunhill Medical Trust, researchers found that the parasite causes the excess production and release of dopamine in the infected brain cells. Aspects of the brain that control cognition, movement and behaviour come from the natural chemical dopamine. Dopamine also helps control the brain’s reward and pleasure centres and regulates emotional responses, such as fear. A certain kind of dopamine receptor is also linked to sensation-seeking. Deficiency of this chemical in humans results in Parkinson’s disease.

Dr. McConkey concludes that, “Based on these analyses, it was clear that T. gondii can orchestrate a significant increase in dopamine production in neural cells. Humans are accidental hosts to T. gondii and the parasite could end up anywhere in the brain, so human symptoms of Toxoplasmosis Infection may depend on where the parasite ends up. This may explain the observed statistical link between incidences of Schizophrenia and Toxoplasmosis Infection.”

The next steps in experimental research of the subject will involve determining how dopamine production is triggered by the parasite enzyme, and how it may change behaviour.


Brain Parasite Directly Alters Brain Chemistry – T gondii Affects Dopamine. (2011, November 4). Retrieved from Neuroscience

Brain Parasite Directly Alters Brain Chemistry. (2011, November 4). Retrieved from Science Daily:


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