Dangerous toxoplasmosis often causes severe late effects in the brain

Toxoplasmosis affects memory in old age
Infection with Toxoplasma gondii can be particularly dangerous for pregnant women. This could affect the health of newborns. But the dangerous pathogen apparently has clearly longer-term effects. According to researchers, an infection can also affect memory in old age.

Every second German carries pathogens in the body
Recently, U.S. scientists reported that some cat owners were found to have an increased likelihood of aggression and sudden anger. Those who had been infected by Toxoplasma gondii. Every second German is the carrier of this pathogen. The globally occurring unicellular organism causes one of the most common infectious diseases, toxoplasmosis.

Especially dangerous for pregnant women and newborns
This disease is mainly known in connection with health risks for people with weakened immune systems and during pregnancy. If an expectant mother becomes infected, this can lead to permanent malformations and damage in the child. Unfortunately, toxoplasmosis often remains undetected in newborns, experts from the Robert Koch Institute (RKI) reported in the scientific reports magazine. This can also have a negative impact much later.

Impairment of working memory in old age
Studies at the Leibniz Institute for Labor Research at the TU Dortmund (IfADo) have now shown that an infection can also impair working memory in old age. As the university reports in a current report, the parasite Toxoplasma gondii only multiplies in the intestines of cats. The robust parasite eggs find their way into foreign organisms, for example from mice or birds, via the cat's droppings.

According to this, humans often become infected through contact with contaminated water, vegetables or undercooked meat from infected farm animals. In the majority of cases, the infection remains unnoticed, but the gastric acid-resistant pathogens can cross the blood-brain barrier and nest in nerve cells for life.

Decreased quality of life
According to their own statements, the scientists at IfADo have now investigated for the first time whether this affects cognitive abilities. In a double-blind study with seniors, they were able to show that a latent infection can impair memory performance and subjective quality of life. To do this, they tested two groups of over 65-year-olds, one half was latently infected with toxoplasmosis and the other was not. They reported their results in the journal “Biological Psychology”.

Lower working memory performance
All subjects had to answer questions about the life situation and quality of life. This was followed by various PC tests on attention, memory, ability to concentrate and speed of information processing.

Among other things, the participants should always press a key in a rapid sequence of individual letters if the penultimate letter matched the one currently shown. In this way, letters have to be stored in short-term memory and continuously compared with the new letters.

It was shown that the working memory performance of the toxoplasmosis-positive subjects was 35 percent lower than that of the non-infected. In addition, the people concerned rate their physical, psychological and social quality of life significantly worse. The deficits in memory performance found were objectified with EEG-based examinations.

Relationship between toxoplasmosis and dementia
"The difference in working memory performance between infected and uninfected roughly corresponds to the difference between healthy young adults and seniors," explained IfADo study author Dr. Patrick Gajewski.

According to the experts, an imbalance in the neuronal messenger balance of dopamine and norepinephrine caused by the toxoplasmosis infection is blamed for the effects. Therefore, a connection between toxoplasmosis and dementia should be investigated in subsequent studies, since in both cases the memory function is affected first. "The high prevalence of toxoplasmosis infection and a growing number of older people illustrate the socio-economic importance of the findings," said Gajewski. (ad)

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Video: Parasitology 099 a Toxoplasma Gondii Coccidea Cat Parasite AIDS Congenital Toxoplasmosis (September 2021).