A link between gum disease and greater rates of cognitive decline in people in the early stages of Alzheimer's disease has been found in a new study.
Periodontitis, or gum disease, is common in older people and may become more common in those with Alzheimer's because of a reduced ability to take care of oral hygiene as the disease progresses.
Higher levels of antibodies to periodontal bacteria are associated with an increase in levels of inflammatory molecules elsewhere in the body, which in turn have been linked to greater rates of cognitive decline in Alzheimer's disease in previous studies.
The research, jointly led by the University of Southampton and King's College London, involved 59 participants with mild to moderate Alzheimer's disease who were cognitively assessed and a blood sample was taken to measure inflammatory markers in their blood.
Their dental health was assessed by a dental hygienist who was blind to cognitive outcomes.
The majority of participants (52) were followed up at six months, when all assessments were repeated.
The presence of gum disease was associated with a six-fold increase in the rate of cognitive decline in participants over the six-month follow-up period of the study.
Periodontitis was also associated with a relative increase in the pro-inflammatory state over the six-month follow-up period.
The authors of the report, published in the journal PLOS ONE, concluded that gum disease is associated with an increase in cognitive decline in people with Alzheimer's disease, possibly via mechanisms linked to the body's inflammatory response.
Professor Clive Holmes, senior author from the University of Southampton, said: "These are very interesting results which build on previous work we have done that shows that chronic inflammatory conditions have a detrimental effect on disease progression in people with Alzheimer's disease.
"Our study was small and lasted for six months, so further trials need to be carried out to develop these results. However, if there is a direct relationship between periodontitis and cognitive decline, as this current study suggests, then treatment of gum disease might be a possible treatment option for Alzheimer's."
Dr Mark Ide, from the Dental Institute at King's College London, said: "A number of studies have shown that having few teeth, possibly as a consequence of earlier gum disease, is associated with a greater risk of developing dementia.
"We also believe, based on various research findings, that the presence of teeth with active gum disease results in higher body-wide levels of the sorts of inflammatory molecules which have also been associated with an elevated risk of other outcomes such as cognitive decline or cardiovascular disease. Research has suggested that effective gum treatment can reduce the levels of these molecules closer to that seen in a healthy state.
"Previous studies have also shown that patients with Alzheimer's disease have poorer dental health than others of similar age and that the more severe the dementia the worse the dental health, most likely reflecting greater difficulties with taking care of oneself as dementia becomes more severe."