Poor oral hygiene has been linked to brain shrinkage, according to a study by researchers at Tohoku University in Japan. The study, published in the journal Neurology, found a correlation between gum disease and tooth loss and a reduction in the volume of the hippocampus, a brain region responsible for memory and associated with Alzheimer’s disease. The researchers examined 172 participants, aged an average of 67 years, who had no memory problems at the start of the study. The participants underwent dental examinations and memory tests at the beginning of the study, and their hippocampal volume was measured using brain scans at the start and after four years. The researchers counted the number of teeth for each participant and checked for gum disease by measuring the depth of the periodontal pockets.
The study found that the number of teeth and the extent of gum disease were linked to changes in the left hippocampus of the brain. In people with mild gum disease, a lower tooth count led to faster shrinkage in the left hippocampus. However, in people with severe gum disease, a higher tooth count led to faster shrinkage in this brain region. After adjusting for age, the researchers found that in people with mild gum disease, the increase in brain shrinkage due to a missing tooth was equivalent to almost one year of brain aging. For people with severe gum disease, the increase in brain shrinkage due to an additional tooth was equivalent to 1.3 years of brain aging.
The study does not prove that gum disease or tooth loss directly leads to Alzheimer’s disease, but it does establish a correlation. The lead author of the study, Satoshi Yamaguchi, emphasised the need for future studies with larger groups of people. The study was conducted in a region of Japan, so the results may not be applicable to other locations. Nevertheless, the findings provide further evidence of the importance of good oral hygiene for overall health, particularly for the brain region responsible for thinking and memory.
