The lack of a species associated with brain metabolism is associated with this disorder

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Talking about suicide is still taboo in many societies. However, it is a very present fact. In many countries it is the second cause of death among adolescents and young people. In a study done a dozen years ago with almost 85,000 adults from 17 countries, it was detected that 9.2% of the general population have had or have suicidal thoughts. As for adolescents and young people, in another much more recent study, done in 2019, of more than 16,000 university students from 108 academic institutions around the world, it was seen that 24.3%, i.e. almost 1 in 4 had had suicidal thoughts and 9.3%, that is almost 1 in 10, had attempted suicide at least once.


These appalling data indicate the need to delve into studies of all kinds – sociological, psychological, biological...– to understand the causes and find strategies to reduce the number of those affected as much as possible. In general, one of the most influential causes in suicide, self-harm and mental health is stress. However, she is not the only one. A University of Florida research team led by microbiologist Eric W. Triplett has studied the relationship between gene variants involved in the functioning of the immune system and the presence of certain bacteria in the oral microbiota with the possibility of having suicidal thoughts. As they have published in Scientific Reports, people who have had suicidal thoughts have an altered oral microbiota and a higher genetic probability of having gingival inflammation, which allows us to think about possible measures to decrease the incidence of these thoughts among adolescents and young people.


The possible causes of having suicidal thoughts are many and varied. Sociological ones have been identified, according to the environment in which a person has grown up, lives and develops; of psychological ones, according to each person's personality in relation to the environment in which they live; of diet-related ones, in which a healthy and balanced diet that respects all daily meals and avoids toxic substances decreases the likelihood of having suicidal thoughts, and also of biological ones, due to certain neural configurations that may be congenital. However, the most prevalent cause is stress. It has long been known that there is a correlation between the level of stress and the likelihood of having suicidal thoughts or self-harm. In this way, during adolescence and early youth the level of stress tends to be a little higher than at any other stage of life, due to biological causes related to the changes specific to this age. This implies that any reason that increases it further, as can sometimes happen with studies, increases the likelihood of having these thoughts.


Suicidal thoughts and oral health

Triplett and his collaborators looked at the biological causes related to oral health. It was known that there is a correlation between the presence of inflammation in the gums and the likelihood of having suicidal thoughts. These gingival inflammations can have several causes, related to the functioning of the immune system and the bacteria present in the oral cavity, the so-called oral microbiota. The researchers asked a group of 489 college students to complete a standardized questionnaire that detects depressive symptoms and includes questions about possible suicidal thoughts, called the PHQ-9. They found that a total of 60 (which represents 12.26% of the total, or 1 in 8 students) had had suicidal thoughts in the past two weeks. Then,


On a genetic scale, it was seen that, unlike the rest, many of those who had had suicidal thoughts had certain gene variants in the system called HLA, or major histocompatibility complex, which favor certain autoimmune and inflammatory responses. This fact corroborates the correlation between certain gene variants, the likelihood of suffering from gingival inflammation and the possibility of having suicidal thoughts, emphasizing, as the authors of the work say, the importance of maintaining good oral hygiene to reduce the likelihood of having inflammatory processes.


However, possibly the most surprising result was demonstrating the relationship that exists between the oral microbiota and suicidal thoughts. They saw that, also unlike the rest, all the students who had had suicidal thoughts at some point in the past two weeks had greatly decreased populations of a typical mouth bacteria called Alloprevotella rava. This bacterium produces an acid-like substance that promotes brain metabolism and, in turn, mental functions, including mood. Although this study does not allow us to clarify whether the decrease in these bacteria is part of the cause of having suicidal thoughts or if it is a consequence of the reasons that have led to having them, the authors suggest that probiotic supplements that help maintain optimal levels of these bacteria in the oral microbiome could contribute to reducing the incidence of these thoughts among the adolescent and young population.