Tohoku University Study Reveals: Patients with 'Underbite' (Malocclusion) Have Drastically Reduced Cerebral Blood Flow During Chewing Compared to Healthy Individuals, Directly Linking to Future Cognitive Decline Risk

Going beyond the general idea that “chewing food well” increases blood flow to the brain and maintains cognitive function, a shocking reality has been revealed by a research group at Tohoku University: in patient groups with actual abnormalities in jaw morphology (such as an underbite), the increase in blood flow to areas directly linked to cognitive function, centered on the prefrontal cortex, during the act of chewing is drastically reduced to “about half” that of healthy individuals. This is the latest report corroborating that poor teeth alignment and low chewing efficiency are deeply involved in the potential risk of developing dementia in the future.

Details of this research result can be confirmed in the official press release of Tohoku University in 2026 and related papers.

Analysis of the Relationship Between Cerebral Blood Flow During Chewing and Cognitive Function in Patients with “Underbite” | Tohoku University https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20260203_web03_prognathism.pdf

Significant Decrease in “Cerebral Blood Flow (CBF)” During Chewing

Normally, when healthy individuals chew food, accompanied by intense sensory input and motor output through the trigeminal nerve, blood vessels such as the internal carotid artery and middle cerebral artery dilate. This immediately sends a rush of blood flow (Cerebral Blood Flow: CBF) containing oxygen and glucose to the command center areas of each brain, including the prefrontal cortex (the area governing working memory and executive function).

However, an experiment targeting patients with prognathism, a type of jaw deformity generally known as an “underbite,” uncovered the following serious fact of decreased blood flow.

• When observing blood flow fluctuations near the prefrontal cortex during gum chewing using a state-of-the-art blood flow measurement device, the control group with healthy occlusion recorded a high wave of blood flow along with the start of chewing.
• On the other hand, the extent of the increase in blood flow during chewing in the patient group with an underbite remained at “about 50%” of the increase recorded by the healthy group, confirming that brain activation was triggered only at an extremely low level.

According to the researchers’ points out, the background is that in people with structural problems such as malocclusion, the area where the teeth correctly contact each other is narrow, making the transmission of muscle power during chewing inefficient, and the chewing efficiency itself is reduced by about 30 to 50% compared to healthy individuals.

The Mechanism Where the “Brain’s Compensatory Mechanism” and Potential Risks Due to Aging Manifest

Furthermore, the research conducted a detailed correlation analysis within the patient group regarding “the relationship between the peak of blood flow during individual chewing and cognitive function (scores on attention/executive function tests, etc.).”

What should be noted here is that in the age group of the patients targeted this time (young to middle-aged), although there was no dramatic drop in the baseline cognitive function scores themselves compared to the healthy group, when analyzing the breakdown of the patient group, there was a clear positive correlation: “patients with higher cerebral blood flow during chewing clearly maintained higher cognitive function scores.”

This suggests a pathological model where, in the young to prime-of-life period, the penalty of continuous reduction in cerebral blood flow itself continues to function quietly. It does not surface because the “compensatory mechanism (the function of covering the missing network with other areas)” as the brain’s reserve capacity is barely functioning. In other words, the view is that the “lack of a cerebral blood flow boost during meals” three times a day caused by low chewing efficiency accumulates over a span of ten to several decades. It is highly likely that at the moment this coincides with the decline of the brain’s compensatory mechanism due to aging, it will manifest in the form of rapid functional decline in the hippocampus and frontal lobe (progression of severe dementia).

Re-evaluation of the Blood Flow Pump Action Through Occlusal Recovery and the “Habit of Chewing”

The findings of this study completely surpass vague effects like “chewing makes you smarter” and prove the mechanism that the physical energy possessed by the masticatory organs is designed as a hydrodynamic and nutritional supply source (blood flow pump device) straight into the cranium.

To leave mechanical errors untreated, such as tooth loss due to cavities or aging, or malocclusion, and depend on a soft diet (meals that do not need to be chewed) is tantamount to the act of voluntarily shutting down the daily blood flow booster necessary for the brain. It is said that the “recovery of an anatomical structure capable of chewing” through orthodontics, implants, and appropriate dentures, and the very act of firmly crushing solid foods during meals, will function as a direct brain protection program to avoid the risk of nursing care (advanced dementia) in the distant future.