Wayne State researcher Alan Hudson, PhD, announced results of a study which
links the bacterium Chlamydia pneumoniae to brain samples from late-onset
Alzheimer’s patients. Analyses showed that, in 17 of 19 patients, brain areas with
typical Alzheimer’s pathology showed the presence of Chlamydia pneumoniae (C.
pneumoniae). The bacterium, however, was not present in unaffected brain regions of
the same patients; furthermore, it was present in only one sample from one brain area in
one of 19 non-Alzheimer’s control patients. This finding potentially could lead to
new diagnostic and treatment regimens in the battle against Alzheimer’s disease.
"While our results have to be confirmed by others, the findings, along with our ability to culture the organism from infected brain tissues, may suggest that infection with C. pneumoniae is a risk factor for late-onset Alzheimer’s disease," said Dr. Hudson, associate professor of immunology and microbiology. "C. pneumoniae is very common in all parts of the world. Nearly everyone has been exposed to it at some point in their lives. Although simply having the organism doesn’t mean you will get Alzheimer’s, it may be a risk when combined with other genetic factors."
Dr. Hudson collaborated on this study with colleagues from the MCP-Hahnemann School of Medicine at Allegheny University of Health Sciences in Philadelphia and Johns Hopkins University School of Medicine in Baltimore. They published their findings in the August issue of the journal Medical Microbiology and Immunology.
C. pneumoniae is a common respiratory pathogen that is significantly present in acute respiratory infections, including pneumonia, sinusitis, and bronchitis, and studies have associated it with more severe and chronic pulmonary conditions including chronic obstructive pulmonary disease. Although the organism is closely related to the bacterium known as Chlamydia trachomatis which causes a sexually-transmitted disease, C. pneumoniae has not been implicated in sexual transmission. It is purely a respiratory pathogen and is not a sexually-transmitted form of Chlamydia.
The research team is now investigating causes and risk factors relating to the development of Alzheimer’s disease. They hope to answer such questions as how the bacterium enters the brain, whether it is a primary cause of the disease or a secondary complicating factor in its pathogenesis, how long the organism remains in the nervous system, and whether some specific strain of this bacterial species is responsible for neurological disease.
The darkened areas pictured here represent damaged cells in the brains of patients with Alzheimer’s disease.
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