Little evidence was found in a review of recent literature that Lyme disease causes Alzheimer disease (AD) or Lewy body dementia (LBD). This perspective was published in Clinical Infectious Diseases.
Patients with Lyme disease often report disturbances to concentration or memory, and some patients report residual cognitive symptoms after treatment. One study found that compared with control patients without Lyme disease, patients with untreated Lyme disease reported significantly more difficulty concentrating or memory problems (P =.004). However, studies that used neurocognitive testing typically did not find significant cognitive deficits among patients with Lyme disease.
Dementia occurring as a result of Lyme disease is reported more frequently in Europe due to the common causative bacteria in that geographic location. The best documented cases for dementia from Lyme disease have clinical features that resemble normal pressure hydrocephalus with abnormal cerebrospinal fluid biochemistry.
An infectious cause of Alzheimer disease has been proposed in the literature, with suspected microbes including herpesviruses, Chlamydophila pneumoniae, Porphyromonas gingivalis, Treponema spp, Helicobacter pylori, Propionibacterium acnes, Burkholderia spp, or fungi, as well as a polymicrobial causation. However, studies have not found evidence of these microbes in brain tissue among patients with Alzheimer disease.
There is also a lack of geographic correspondence between fatal cases of Alzheimer disease and Lyme disease in the United States. A study in Denmark did not identify a link between Lyme neuroborreliosis and long-term risk for dementia, Alzheimer disease, Parkinson disease, motor neuron disease, or epilepsy. A study in France of retired farmers did not report increased risk for dementia among individuals who were seropositive for one of the Lyme disease-causing bacteria, Borrelia burgdorferi sensu stricto. The review authors highlighted the fact that the lack of an animal model of B burgdorferi sensu stricto impedes investigators from adequately assessing the potential link between Lyme disease and Alzheimer disease.
A recent, single-patient case report called in to question whether Lyme disease may cause Lewy body dementia. The patient had early Lyme disease that had been treated with doxycycline, which is highly effective for Lyme neuroborreliosis. The patient had a multiyear gap between treatment of the early Lyme disease and cognitive decline. No significant difference in B burgdorferi sensu stricto detection in postmortem tissue samples was noted between the case patient and controls.
The review authors cited multiple limitations of this case report, including sequencing and immunofluorescence assay approaches and discordance in the presence of B burgdorferi sensu stricto in the region where the case patient lived.
The review authors concluded there has been no convincing evidence published to date to support Lyme disease as a cause for Alzheimer disease or Lewy body dementia.
Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.
Wormser GP, Marques A, Pavia CS, Schwartz I, Feder HM Jr, Pachner AR. Lack of convincing evidence that Borrelia burgdorferi infection causes either Alzheimer’s disease or Lewy body dementia. Clin Infect Dis. Published online November 29, 2021. doi:10.1093/cid/ciab993