Assertions of a potential link between Lyme disease and Alzheimer’s deaths have been shown baseless by new research at the University of Toronto Mississauga
A U of T Mississauga release notes that while researching his book “The Alzheimer’s Epidemic—Searching for Causes and a Cure” (Emeritus Books),
U of T Mississauga Professor Emeritus Danton O’Day was intrigued to discover studies and popular professional opinion supporting a potential link between Lyme disease and Alzheimer’s deaths. In 2012, there were 315 reported cases of Lyme disease in Canada, although the Canadian Lyme Disease Foundation estimates the actual number to be in the thousands. Alzheimer’s disease affects 750,000 Canadians.
According to Texas A&M University’s Lyme Lab, Lyme disease (LD) is a zoonotic, tick-borne illness spread to humans through the bite of ticks infected with corkscrew-shaped bacteria known as Borrelia burgdorferi. Part of the spirochete family of bacteria, B. burgdorferi can cause neuroborreliosis, which can lead to dementia. Alzheimer’s disease causes a similar loss of cognitive ability and, eventually, death.
Lyme is the most prevalent arthropod-borne infection in the United States, with a total of 22,572 human cases of Lyme disease reported to the CDC in 2010. Dogs, cats, horses, and cattle can also suffer from LD.
Infected tick vectors transmit the LD causative agent while biting humans and susceptible domestic animal species. The TAMU Lyme Lab notes that a significant increase in the number of reported cases has been observed in the past few years, classifying Lyme disease as a re-emerging infection. Lyme borreliosis is, therefore, an important public health issue, particularly in endemic areas where it contributes to significant rates of morbidity. Lyme disease occurs as a multi-systemic disorder leading to carditis (10% of untreated adults), arthritis (60% of the cases) and other neurological symptoms. Moreover, there are few therapeutic solutions for Lyme disease patients and there are no effective vaccines available on the market.
A recent study conducted by an international research team from seven U.S. and Mexican universities and institutions has confirmed that risk for Lyme Disease is significant in the state of Texas and northern parts of Mexico, and determined that the tick-borne bacterial infectious agent that causes LD is now endemic to the Texas/Mexico border region and likely to remain so, with a higher probability of occurrence along the Gulf Coast.
The researchers, including representatives of the College of Veterinary Medicine & Biomedical Sciences at Texas A&M University, the University of Texas, and Texas State University have effectively refuted previous contention and speculation that Lyme disease is relatively non-existent in the southern United States.
Studies have suggested a link between LD and Alzheimer’s because earlier research had detected the presence of spirochete bacteria, including B. burgdorferi, in the brains of individuals with Alzheimer’s disease.
“Lyme disease can be easily detected and cured with antibiotics,” Dr. O’Day explains. “In contrast, the causes of Alzheimer’s disease remain unknown and there is no cure.”
To investigate whether there was any substance to this unproven but potentially fatal relationship, Dr. O’Day collected data from the U.S. Centers for Disease Control and Prevention on reported incidence of Lyme disease and Alzheimer’s-related deaths. Together with Andrew Catalano, a recent PhD graduate from O’Day’s research group who is now a post-doctoral fellow at City College of New York, O’Day compared data to see if states with high incidences of Lyme disease also showed a high incidence of deaths related to Alzheimer’s.
The research which was was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), was published in the August 2014 issue of the Journal of Alzheimer’s Disease entitled “A Lack of Correlation between the Incidence of Lyme Disease and Deaths due to Alzheimer’s Disease” (Journal of Alzheimer’s Disease DOI 10.3233/JAD-140552), coauthored by Danton H. O’Day (Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario and that Department of Cell and Systems Biology, University of Toronto, Toronto, Canada) and Andrew Catalano (Department of Chemistry, City College of New York, New York).
The coauthors note that reports suggesting Lyme disease (LD) causes Alzheimer’s disease (AD) have appeared in academic journals and online, reasoning that if the biological agent Borrelia burgdorferi that causes LD also causes AD, then areas with the highest levels of LD should have significantly higher numbers of deaths due to AD compared to low LD areas.
In this study, the researchers show there is no statistically significant correlation between the incidence of LD and deaths due to AD in the US.
The scientists found that in fact the 13 states with the highest incidence of Lyme disease actually reported the lowest number of deaths due to Alzheimer’s. Moreover, seven of the states with high incidences of Alzheimer’s deaths were among the 13 states with the lowest incidence of Lyme disease. Vermont was the only state that reported a high incidence of both diseases.
“Statistical analyses revealed a complete lack of correlation between the two diseases, strongly suggesting that Lyme disease could not be the cause Alzheimer’s,” says Dr. O’Day.
The United States is the only source to report location-specific data on the two diseases, but Dr. O’Day says that the findings are equally relevant in Canada. “While such complete data does not exist in Canada to make equivalent comparisons, there are no valid reasons this conclusion would not hold here as well as for any other country world-wide.”
“Because of this growing impact Alzheimer’s disease will have in Canada and world-wide, we need to understand the true factors that underlie the disease,” Dr. O’Day observes. “We need to quickly rule out concerns, like Lyme disease, that unnecessarily cause widespread fear and interfere with attempts to fully understand the causes of Alzheimer’s disease.”
University of Toronto
Texas A&M University Lyme Lab
Journal of Alzheimer’s Disease
University of Toronto
Dr. Danton O’Day