Tooth loss doesn’t just make eating harder, it may also make thinking more challenging. A study in Japan shows that ageing mice missing their molars experience measurable cognitive decline, even when their nutrition remains perfectly intact.
The results by a team at Hiroshima University are published in the Archives of Oral Biology.
“Tooth loss is common in ageing populations, yet its direct neurological impact has remained unclear,” Rie Hatakeyama said.
“Our study examines whether tooth loss itself, independent of nutritional deficiency such as a low-protein diet, can cause cognitive decline in male mice.”
Experimental tooth loss in SAMP8 mice was associated with cognitive decline and increased neuronal inflammation in the hippocampus, while the effects of a low-protein diet on neuroinflammation were limited.
To explore how chewing ability and nutrition jointly influence the brain, the research team used ageing-prone male mice and assigned them to one of four conditions: a normal-protein diet with no tooth extraction, a low-protein diet with no extraction, molar extraction with a normal-protein diet, and molar extraction with a low-protein diet.
After six months, the mice underwent behavioural tests and detailed analyses of their brain tissue for markers of inflammation, neuronal loss, and cell death–related gene expression.
The results were striking: mice that lost their molars showed significant memory decline even though they received the same diet as the control groups.
“This suggests that reduced masticatory stimulation, not dietary protein intake, contributes to cognitive deterioration,” Hatakeyama said.
“It is surprising that a peripheral event in the mouth can so profoundly affect the central nervous system.”
Brain tissue analysis supported these behavioural findings.
