As reported earlier this week*, a retired professor and a PhD graduate student from the University of Toronto Mississauga claim that they have disproved the theory that Lyme disease causes Alzheimer's disease. But, exactly how did they disprove a link? Did they test a large number of Alzheimer's patients for Borrelia burgdorferi antibodies using several assays? No. Did they employ an expert pathologist - one highly-skilled and experienced in the tedious process of identifying Borrelia spirochetes - to perform extensive autopsies on a large number of deceased Alzheimer's patients? Negative. Did they track a large number of Lyme disease patients for decades to see whether any of them developed symptoms of Alzheimer's disease? Nope.
The researchers say they used "statistical analysis" to disprove an Alzheimer's-Lyme link. By noting where the reported cases of Lyme disease occur vs. where people with Alzheimer's disease are found, they say they’ve ruled out the possibility that Lyme disease may cause Alzheimer’s disease.
Well, their theory may have actually held weight except in the case of controversial Lyme disease, where, sadly, it’s not so simple. The researchers seem to have made several assumptions without an investigation of the caveats and actual facts. These facts may blow their “There is no Lyme-Alzheimer link” conclusion right out of the water.
At GALDA, we thought of four important reasons that an Alzheimer’s-Lyme disease link cannot be ruled out using geographical disease statistics. Maybe you can think of more.
1. Reporting practices are not the same. The authors of the paper apparently didn't actually check, but used the assumption that all states/regions use the same Lyme disease reporting practices. They don’t, and they haven’t for decades. There are potentially thousands of Lyme disease cases that are never reported in states outside the northeastern USA simply because those states use completely different reporting practices. There is no way to compare Lyme disease statistics when rashes alone are reported as cases in the northeastern USA and rashes alone are not reported as cases elsewhere. (Note: It’s estimated that cases involving rashes alone without evidence of tick bite or positive test results make up 70% of cases reported in so-called “Lyme endemic states". Thousands and thousands of cases of rashes following tick bites (many even with serological evidence suggestive of LD) go unreported in so-called “nonendemic areas" because rashes alone do not qualify to be reported as cases in these regions.)
2. Federal funding to track Lyme disease is awarded in a biased way. Adding to reporting practice problems, most state health departments have not been provided federal funding to actually track Lyme disease cases, a very expensive, labor-intensive task. The states awarded funding to track the disease become the states where reported Lyme disease incidence rates are high. (Duh!) How many actual cases would all states show if they were also awarded federal funding and were allowed to use the exact same criteria to report a case? Statistics cannot be compared when only a few states have money to actively track Lyme disease.
3. North American Lyme tests are not designed to detect infection caused by various Lyme bacterial species. Lyme disease statistics may not reflect the hundreds to hundreds of thousands of patients who are infected with other Lyme disease bacterial species each year. There is so much that is unknown, but with more and more newly-identified strains of Lyme bacteria being discovered in various tick species, animals and symptomatic humans in America and around the world, the probability that there are a vast number of undetected Lyme Borreliosis cases caused by bacterial species other than Borrelia burgdorferi sensu stricto is great. While European Lyme tests include three species of Lyme Borrelia to increase their reliability, clinical Lyme disease tests currently used in North America are only geared to detect a single strain of one species of Borrelia burgdorferi (Bb). This is preposterous. In the southeastern USA alone, there are at least six species of Lyme bacteria documented (and potentially hundreds to thousands of strains of each species) but U.S. clinical tests only look for one. Thus, there’s no telling how many suffering people in North America may actually be infected with some form of Lyme Borreliosis. Using better tests designed to detect more Borrelia strains, we may discover that Lyme disease is actually extremely prevalent in regions where it is now currently considered “rare.” Here again, trying to geographically compare Alzheimer's disease and Lyme Borreliosis case numbers is impossible.
4. Unproven myths greatly affect statistics. Myths and misconceptions such as, Lyme disease doesn't occur in this region, prevent cases from being recognized, diagnosed, treated and reported by medical providers. As an example, the State of Georgia provided funding for free Lyme testing in 1989 and actually encouraged physicians to look for the disease. Subsequently, Georgia reported 715 Lyme disease cases to the CDC that year, the fourth highest state in the nation. But, with no money to track future cases and a new widespread but unproven myth circulating that erythema migrans (EM) rash and Lyme disease symptoms in tick bite patients in the southern USA "is not Lyme disease,” but is caused instead by some “unknown" entity, Georgia case numbers plummeted.
( As officials began to actively discourage medical providers from looking for Lyme disease in the South, most southern states thereafter did not use the national reporting case definition - despite published evidence showing Missouri lone star tick bite EM patients tested positive for Lyme disease by the CDC and Borrelia spirochetes were silver-stained and documented under the microscope in some of these cases.)
Though for decades, thousands of southern tick bite patients have developed a rash, Lyme symptoms and tested positive for Lyme disease, myths - including the circular reasoning, We don’t have Lyme disease here so we can’t have Lyme disease here, and, Positive test results outside “endemic areas” are only false positives - continue to prevent the diagnosis and treatment of suffering patients. Misconceptions such as these greatly contribute to the under-reporting of Lyme disease in entire regions.
In conclusion, a statistical analysis of reported case numbers may be a good method of extracting and comparing important data in many instances, but in the world of Lyme disease, it’s nearly pointless. Clearly, the researchers thought they might produce valid evidence. Unfortunately, they didn't investigate thoroughly enough. Considering the many problems, an accurate geographical comparison of Lyme disease statistics with other diseases, including Alzheimer's, cannot possibly be made at this time.
*UTM study disproves theory that Lyme disease causes Alzheimer's, The Brampton Guardian, July 31, 2014