Patients with Alzheimer's disease who have common bacterial infections suffer greater memory loss, claims a recent study published in Neurology. The effect is said to be linked to increased levels of the pro-inflammatory cytokine tumour necrosis factor (TNF) caused by systemic inflammation.
Previous research has suggested that acute systemic inflammation might exacerbate neurodegeneration, so the researchers, based at the University of Southampton, UK, measured the level of TNF in the blood of 222 elderly people with Alzheimer's disease and assessed their ability to perform cognitive tests over a 6 month period. Any illnesses or injuries were also recorded. Patients with higher TNF levels at the start of the study had four times the rate of cognitive decline as those with low levels of TNF, and patients who experienced at least one infection or injury over the course of the study also performed worse in cognitive tests. “The worse the infection the worse the affect on the memory”, said Professor Clive Holmes, the lead author of the study (
BBC News
, 7 Sep 2009).
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