We are part of a very dynamic world: many of us live in big metropolis, fighting against traffic, overcrowded public transportation and delays. In all of these we need to work hard to earn a little money, taking also care of interpersonal relationships with friends, relatives, partners and colleagues. Then, we need to plan our life, because at some point we would like to buy a car, a house and having children, while managing bills, savings, expenses for essential living and trying to grow in our career. To be honest, this life looks very stressful and the risk of failure is behind the corner! However, there are people that can better cope with all of this, while others cannot, leading also to many mental disorders. So, what are the differences? Apart from our busy life, are there other causes giving predisposition to mental illness?
When talking about psychological problems, we dive into a sort of dark area due to its complexity and myriad of different factors that can be involved in human behavior. Current medicine sees mental illness mainly coming from psychological factors, like emotional trauma, a dysfunctional family life, changing job, etc. But are we sure these are the only factors?
We need to understand that our body is an unique system, relying on the balance of three elements, structural, chemical and mental (Figure 1), which mutually influence each other: the health of the individual is found when the balance between the three persists. Think about physical activity (structural) that increases dopamine level (chemical) and gives us satisfaction, improving mental health (mental) . Or think about fear (mental) that releases adrenaline (chemicals), increasing tension in skeletal muscles (structural) [2,3].
All health problems, either physical or mental, involve an imbalance of one part or more of this triad. For example, fibromyalgia can have structural causes, dictated by myofascial pain coming from body misalignment , which affect dopamine  and glutamate  levels (chemical). Fibromyalgia can also have chemical causes, from metal intoxication [7,8], with consequent physical pain (structural). Finally, who fibromyalgia sufferers also experiences depression and anxiety (mental) [9,10].
In our modern society, both chemical and structural balances have been strongly compromised, so repercussions on the mental side are obvious. The chemical balance mainly derives from the air we breathe, the water we drink and the food we eat. Smoking (air) is associated with greater perceived stress, poorer overall subjective quality of life, and lower life satisfaction . Domiciliary air pollution causes behavioral disturbances (e.g. self-regulatory ability, aggression, depression) [12,13]. Dioxins decrease nerve conduction velocity and impaired mental development of children .
Nutrition also plays an important role in chemical balance, thus mental health. We mostly eat ultra-processed ready meals that miss all the important nutrients that our body needs, such as vitamins, minerals, and omega-3 fatty acids. A notable feature of the diets of patients suffering from mental disorders is the severity of deficiency in these nutrients . Deficiencies in neurotransmitters, like serotonin that is synthesized from tryptophan (an amino acid present in most protein-based foods), are often associated with depression . Consumption of omega-3 fatty acids, rich in seafood, reduces depression, aggression and anger while improving mental well-being .
Structural balance depends on our body structure that has been massively compromised in our modern society. We see many people around us with difficulty in practicing any sport, with impaired gait and poor body posture. A poor craniofacial development is what determines the poor body posture. So, is there a connection between craniofacial morphology and mental health? We judge many people from their facial appearance, attributing certain personalities to specific attributes. Figure 2 shows a composite of several faces. Two of these photos were made from the top 10% most extroverted participants of a study, while the other two were made from the most introverted . Can you tell who is who? If you guessed that the left man and the right woman were the extroverts, you were right.
The literature is full of studies trying to link facial features with personality characteristics [19,20,21,22]. There are even algorithms based on Artificial Intelligence able to recognize sexual orientation from facial images . Have a look to Figure 3: can you spot which picture of males and females represents a heterosexual orientation? If you do not, do not worry. Human identifies correct sexual orientation only 61% of the time for men and 54% for women, while algorithms 91% of the time with men and 83% with women. So, if you are wondering whether craniofacial development has an impact on our psychology, the answer is likely positive.
Other researchers developed an algorithm to detect features of the human face associated with criminality . Looking to Figure 4, do you think these three individuals are criminals or not? The algorithm can recognize that these are criminal faces with a 90% accuracy. Also, in the same research, they illustrated the particular facial features that the algorithm relies upon to make the distinction between criminal and non-criminal faces: these are the distance between the inner corners of the eyes, angle between the nose and the corners of the mouth, and the curvature of the upper lip. Interestingly, these facial features are largely influenced by craniofacial development, in particular of the maxilla.
In modern era, we are assisting to a down-siding of the entire craniofacial structure, with the maxilla that drops down and backwards. This reduces the eye support, flattens the cheekbones, narrows the nasal airway, lengthens the mid facial third, influences lips shape, and lowers the palate, which narrows and create malocclusion . Can a poor craniofacial development give predisposition to criminal tendency? Currently we do not know, but there is a clear link. Predisposition does not mean all person with a poor craniofacial development are criminals. However, criminals will often show a poor craniofacial development. Indeed, the human eye is able to distinguish whether a person is a criminal or not . So, in Figure 5, can you distinguish who is a criminal and who is not?
When talking about psychology, it is very difficult to find clear statements and obvious links. Many are conjectures based on empirical observations. Although it is very difficult to theoretically demonstrate the reasons behind certain behaviors, we know there is a strict relationship between body and mind. If our mind suffers, so will our body. If our body suffers, so will our mind. In this sense, a poor craniofacial development can give predisposition to mental illness and to other behavioral and personality patterns. So, do not neglect the importance of the reciprocal influence between body and mind!
 Reis, L. C., and J. R. Hibbeln. “Cultural symbolism of fish and the psychotropic properties of omega-3 fatty acids.” Prostaglandins, Leukotrienes and Essential Fatty Acids 75.4-5 (2006): 227-236.
 Zebrowitz, Leslie A., Mary Ann Collins, and Ranjana Dutta. “The relationship between appearance and personality across the life span.” Personality and Social Psychology Bulletin 24.7 (1998): 736-749.
 Hehman, Eric, Jessica K. Flake, and Jonathan B. Freeman. “Static and dynamic facial cues differentially affect the consistency of social evaluations.” Personality and Social Psychology Bulletin 41.8 (2015): 1123-1134.
 Wang, Yilun, and Michal Kosinski. “Deep neural networks are more accurate than humans at detecting sexual orientation from facial images.” Journal of personality and social psychology 114.2 (2018): 246.
 Valla, Jeffrey M., Stephen J. Ceci, and Wendy M. Williams. “The accuracy of inferences about criminality based on facial appearance.” Journal of Social, Evolutionary, and Cultural Psychology 5.1 (2011): 66.