Infections outside the brain may speed memory decline in Alzheimer′s disease, UK researchers say. In a study of 222 elderly people with Alzheimer′s they found that getting infections in places like the chest or urinary tract could double memory loss. The Southampton University researchers think this leads to higher levels of an inflammatory protein called tumour necrosis factor (TNF) in the blood. They say better care to prevent infections is very important.
The study published in the journal Neurology followed the Alzheimer′s patients for six months. Between them 110 of the 222 subjects developed a total of 150 infections, in areas such as the chest, stomach and intestines and the urinary tract, which led to the production of TNF proteins. These are collectively known as acute systemic inflammation events (SIEs). Subjects with one or more SIEs during the six months follow-up had two times the rate of cognitive decline from their baseline score at the start of the study compared with those who had no SIE. And those patients who had high baseline levels of TNF and then suffered an SIE over the following six months had a 10 fold increase in the rate of cognitive decline compared to those who were SIE free.