Gum disease and tooth loss are linked to hippocampal atrophy and may have a more negative impact on the brain than aging, new research suggests.
Investigators found that in a late middle-aged and older cohort, among patients with mild periodontitis, having fewer teeth was linked to a faster rate of left hippocampal atrophy. For those with severe gum disease, each additional lost tooth was associated with a faster rate of brain shrinkage, equivalent to 1.3 years of brain aging.
“Tooth loss and gum disease, which is inflammation of the tissue around the teeth that can cause shrinkage of the gums and loosening of the teeth, are very common, so evaluating a potential link with dementia is incredibly important,” study investigator Satoshi Yamaguchi, PhD, DDS, of Tohoku University, in Sendai, Japan, said in a release.
“Our study found that these conditions may play a role in the health of the brain area that controls thinking and memory, giving people another reason to take better care of their teeth,” Dr. Yamaguchi noted.
The findings were published online in Neurology.
Greater effect than aging
Although previous research suggests that tooth loss and periodontitis are risk factors for Alzheimer’s disease, longitudinal research has not shown a significant correlation between these conditions and hippocampal atrophy.
To clarify this association, the investigators followed 172 men and women (average age, 67 years) who had undergone two MRI brain scans 4 years apart and had had a dental examination. None of the participants had any signs of cognitive decline at baseline.
At study outset, information on cerebrovascular and cardiovascular disease, alcohol consumption, smoking, depression history, and cognitive function was gathered. The Mini Mental State Exam and dental exams were administered at baseline and at 4-year follow-up.
For each participant, the number of teeth was counted, and all participants were assessed for gum disease via periodontal probing depth (PD).
Healthy gums typically measure between 1 and 3 mm in depth. Mild gum disease is signified by measurements of 3-4 mm in several areas. Severe gum disease involves measurements of 5-6 mm and is accompanied by greater bone loss, leading to potential tooth loss.
Multiple regression analysis was performed, with the annual symmetric percentage change (SPC) of hippocampal volume as the dependent variable. The analysis included an interaction term between the number of teeth present (NTP) and mean PD.
Over the 4-year study period, the investigators found that the qualitative interaction between NTP and mean PD was significant for the annual SPC in the left hippocampus.
Among those with mild periodontitis, having fewer teeth correlated with more rapid atrophy of the left hippocampus, such that every tooth lost was equivalent to nearly 1 year of brain aging.
In contrast, having more teeth was associated with a faster rate of left hippocampal atrophy among those with severe periodontitis and was equivalent to 1.3 years of brain aging.
For those with severe gum disease, each additional lost tooth corresponded to a faster rate of brain shrinkage, equivalent to 1.3 years of brain aging.
“This finding indicates that periodontitis may have a greater association with left hippocampal atrophy than the association exhibited by age. Furthermore, in cases of mild periodontitis, fewer teeth may be associated with a subsequent decline in cognitive function,” the investigators write.
The study’s results, they add, highlight the importance of preserving oral health, not just the retaining of teeth. “These findings suggest that retaining teeth with severe gum disease is associated with brain atrophy,” said Dr. Yamaguchi.
“Controlling the progression of gum disease through regular dental visits is crucial, and teeth with severe gum disease may need to be extracted and replaced with appropriate prosthetic devices,” he added.
The researchers note that further studies are needed to confirm these findings.
The study was supported the Japanese Ministry of Education, Culture, Sports, Science, and Technology; Kelo University; Japan Arteriosclerosis Prevention Fund; Japanese Ministry of Health, Labor, and Welfare; Teiko University; Pfizer Japan; Bayer Yakuhin; Chugai Pharmaceutical; Daiichi Sankyo; Astrellas Pharma; Takeda Pharmaceutical; the Health Care Science Institute; the Health Science Center; and the Takeda Science Foundation. The investigators reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.