Mastication is something so common that we often do not pay attention to it (unless we have a painful tooth). In fact, normally we care of our teeth for aesthetic reasons, because we want to have a beautiful smile. We don’t think that not chewing food properly can also damage our cognivtive resources.
But now it comes an interesting study conducted by researchers at the University of Pisa, which reveals how the way we chew might even cause permanent changes in our brain. So if we have a bad mastication the side effects end up affecting our neurological health.
Chewing helps keep you alert
You probably noticed that the truck or bus drivers often chew a gum, they do it to stay awake. In fact, if you’re sleepy and want to stay awake, rather than use caffeine you can chew a simple gum.
Obviously, there’s an explanation under the neurophysiological point of view: it was found that while chewing not only the attention increases, but also the cognitive processing speeds up. In practice, when chewing we concentrate better and are more careful, so that we respond more quickly to stimuli.
Scientists believe that is an ancestral heritage, because generally, when animals eat are more helpless. It is logical that in this moment they need to sharpen the senses to detect possible dangers and runaway immediately.
Another study conducted by the University of Cardiff found that people who tend to chew gums often report lower levels of anxiety, stress and depression. These researchers believe that systematic mastication activates a pattern of serotonin neurotransmission, which is mainly responsible to inhibit anger and improve the mood.
But what if we chew the wrong way?
The balance of mastication is essential
Several studies carried out with animals have shown that the loss of teeth causes a mandibular imbalance, which in the long run ends up causing the loss of neurons in various parts of the brain, as in the dentate gyrus.
The dentate gyrus is one of the few areas of the brain that can generate new neurons throughout life and is mainly composed of granulosa cells, which can replicate. This structure linked to learning and memory, is thought to be a sort of “unsupervised” instructor who works in storage and retrieval of memories, which is why there may be a link between mastication and some forms of dementia.
In fact, it was also demonstrated that the asymmetrically loss of teeth causes a hypertrophy of astrocytes in the hippocampus (which is essential for the formation of new memories), similarly to when there is a process of neurodegeneration.
These studies indicate that taking care of our mouth is not just a matter of aesthetics, but also has an impact on the brain and can cause damage to the cognitive level. But perhaps the most worrying is a recent research that also shows how chewing problems generate short-term changes in brain activity.
Why symmetry is so important in mastication?
Apparently, the main problem is the asymmetry in mastication. The mandibular asymmetry causes changes in the facial muscles, the most obvious effects are noticed in the face, but produces also internal changes that are not visible.
People with temporomandibular disorders show an asymmetry in the activity of the muscles involved in chewing, which causes a decreased activity in certain brain areas. In fact, epidemiological studies revealed that a severe tooth loss before age 35 is an important risk factor in the development of dementia or Alzheimer’s disease in old age.
Researchers believe that the mandibular asymmetry causes problems at cognitive level because alters the functioning of facial muscles. These, in turn, are connected to the brain, so the chewing process is encoded in a different way and the brain assumes that it is not necessary to activate many neurons since muscles do not work as before. This causes cognitive impairment.
But not everything is reduced to a hypertrophy, a study of the Massachusetts Institute of Technology found that mastication activates the production of a brain-derived neurotrophic factor, which acts as a nerve growth factor, as well as the neurotrophin-3, a protein growth factor that helps existing neurons to survive and differentiate, as well as enhances the growth and differentiation of new neurons and synapses. However, this occurs only when the trigeminal nerve is activated in a symmetrical manner.
Dental implants can be a solution
The good news is that researchers found that dental implants greatly reduce the asymmetry of mastication and the imbalance that occurs in the trigeminal nerve. Therefore, you can stop the cognitive decline early.
Sources:
De Cicco, V. et. Al. (2016) Oral Implant-Prostheses: New Teeth for a Brighter Brain. PLoS ONE; 11(2).
Weijenberg, R. A. et. Al. (2011) Mastication for the mind–the relationship between mastication and cognition in ageing and dementia. Neurosci Biobehav Rev; 35(3): 483-497.
Okamoto, O. et. Al. (2010) Relationship of tooth loss to mild memory impairment and cognitive impairment: findings from the fujiwara-kyo study. Behavioral and Brain Functions; 6:77.
Smith, A. (2009). Chewing gum, stress and health. Stress and Health; 25 (5): 445-451.
Onozuka, M. et. Al. (2000) Impairment of spatial memory and changes in astroglial responsiveness following loss of molar teeth in aged SAMP8 mice. Behav Brain Res; 108(2): 145-155.
Fan, G. et. Al. (2000) Formation of a full complement of cranial proprioceptors requires multiple neurotrophins. Dev Dyn; 218(2): 359-370.
