Study Finds Toxoplasmosis Infection Associated with Frailty Interview with:

Hira Mohyuddin, PGY-2Psychiatry Residency Training Program  The George Washington University

Dr. Mohyuddin

Hira Mohyuddin, PGY-2
Psychiatry Residency Training Program
The George Washington University What is the background for this study?

Response: Frailty has become increasingly significant as the global population grows older, as this syndrome is linked with a higher mortality and morbidity in aging. Causes contributing to frailty are poorly understood, but it seems that the role of inflammation is very likely.

While other chronic infections were shown to precipitate and perpetuate inflammation that contributes to the development of frailty, no prior study has previously focused on possible links between Toxoplasma gondii and geriatric frailty. Benefiting from a collaboration with Spanish and Portuguese researchers, we have now tested, for the first time to our knowledge, this possible association.


Photomicrograph with presence of numerous Toxoplasma gondii: CDC/ Dr. Mae Melvin What are the main findings?

Response:  Among Iberic older adults infected with Toxoplasma gondii (T. gondii), we found a positive association between elevated T. gondii IgG serointensity and frailty. How is toxo infection contracted?

Response:  The permanent hosts of Toxoplasma gondii belong to the cat family. Intermediate hosts can be any warm-blooded animals, including humans. Changes in behavior in intermediate hosts have been reported that favor predation by cats. A chronic infection with mild symptoms is established in intermediate hosts that are immunocompetent; in these hosts T. gondii is confined to intracellular cysts in the brain and muscle, with occasional reactivation, most often limited in time. T. gondii is most commonly transmitted via oocysts originating in cat feces, or via the fecal-oral route or by ingesting tissue cysts in undercooked meat. This infection can also be transmitted vertically from mother to fetus during pregnancy. This form of infection has severe consequences in the offspring. Any form of infection in the immunocompromised host has a severe course, if left untreated. What should readers take away from your report?

Response: Our study was limited by cross-sectional design. Our paper is the first, to our knowledge, to identify a link between T. gondii and frailty. Specifically, serointensity with frailty. This finding implicates possible mechanisms underlying the association between infection severity or virulence and the development of frailty. Given this infection’s tropism for the muscle and the brain, and reported damage on skeletal muscles and CNS effects, future studies may further examine these potential areas for intervention. Early stages of frailty are reversible and ultimately, further research may help identify targets for prevention- primary- by avoiding infection, and secondary, by preventing damage to brain and muscle via direct effects of the pathogen, and even more likely, via activation of the immune system. What recommendations do you have for future research as a results of this study?

Response: First, to replicate this association in longitudinal rather than cross-sectional models. Second, if replicated, to investigate mechanisms and causality. Finally, if results are conducive, to consider a clinical trial using anti Toxoplasma gondii agents in older individuals who are Toxoplasma positive and having a high serointensity and evidence of rapidly reactivating Toxoplasma gondii. Is there anything else you would like to add? Any disclosures?

Dr. Teodor Postolache, Professor of Psychiatry at the University of Maryland School of Medicine

Dr. Postolache

My name is Hira Mohyuddin, MD and I currently train at the George Washington University Psychiatry Residency Training Program. I worked on this project as a mentee of Dr. Teodor Postolache, Professor of Psychiatry at the University of Maryland School of Medicine. He is the senior author of several pioneering articles on Toxoplasma gondii and behavioral dysregulation, including impulsivity, aggression, and suicidal behavior, across diagnostic boundaries. Our next work involves analyses of T. gondii serointensity, and interactions between cognitive deficits and depression in the older adults.


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Hira Mohyuddin et al. Toxoplasma gondii IgG Serointensity Is Positively Associated With Frailty. The Journals of Gerontology: Series A, 2023 DOI: 10.1093/gerona/glad228

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Last Updated on November 18, 2023 by Marie Benz