The Neurobiology of Suicide
by Dr. Raymond B. Flannery Jr. on
From time to time, the news media report on a suicide. The public often assume that the deceased was confronted and overwhelmed by some significant major life event. Most then move on. But loved ones and friends may face additional stress and questions. Some might hold themselves responsible for not doing more to prevent the suicide. Was this a truly willful act by a person with full cognitive capacity? Many in society assume this to be true. What is usually overlooked, however, is that people often face major and difficult life stressors. Yet not everyone commits suicide. Life stressors could include posttraumatic stress disorder (PTSD), serious medical conditions with poor prognoses, serious financial loss, depression, substance abuse, and similar. Again, most people facing these issues do not commit suicide. How are we do understand this paradox? Suicide is a multidetermined act that may include willful acts but may also include psychological, social, and biological components. What if suicide were a medical condition similar to cancer and heart disease? What if there were neurobiological components that are rooted, but not obvious, in the person’s biology? What if the persons committing suicide might themselves be unaware of what was happening neurobiologically inside of them at the time of the suicidal act?
Recent neurobiological research suggests that at least some suicidal behavior appears to be a medical condition similar to cancer and heart disease. Not all suicides are rational willful acts as we usually think of these terms. The medical research on suicide is extensive and growing. This blog focuses on two areas of this neurobiological research rooted in biology: genetics and serotonin-depletion.
The medical field has known for decades that suicide runs in some families. This suggested a possible genetic basis for suicide and has resulted in an extensive body of research, which is usually referred to as “twin studies.” There are two groupings of twins in the twin studies. The first group is that of monozygotic twins in which one egg is fertilized by one sperm and results in two genetically identical offspring. The second grouping of twins is that of dizygotic twins. In this case, one egg splits into two pieces and both are fertilized by two sperm cells producing twins whose genetic materials differ and are not the same as in fully identical, fraternal twins
Medicine also has been interested in the twin studies for examining the transmission of several medical conditions, including suicide, since similar findings in identical twins suggests the possibility of a genetic component. Between 1812 and 2006, there were 32 twin studies that included case reports, twin-registered base populations, epidemiological studies, and studies of surviving twins. Early studies had methodological flaws, but extensive recent findings with sound methodological research have found that suicide rates are higher in identical twins than in fraternal twins (1). These discoveries suggest that at least in some cases there are some neurobiological factors present and that psychosocial factors are not enough by themselves to account for the suicidal act.
While this genetic research was ongoing, a Scandinavian study in 1981 (2) reveals another possible neurobiological clue. Serotonin levels were measured in 119 suicidal or depressed patients. One year later they found that 22 percent of these patients had committed suicide. Was the decline in serotonin related to suicide? Serotonin is a chemical that is present in the mind and body. When it is functioning normally, it controls our moods and feelings, and we feel well. When it is depleted under stress we feel depression, sadness, anger, and experience impaired thinking, memory, and problem-solving abilities. Several subsequent studies have noted this reduced serotonin in depressed individuals, with suicide in some cases. This raises at least two questions: Are some people born with less serotonin? Or is it used up more quickly in some but not others? There is no clear genetic-research data yet to know the answers. However, recent studies note that children who had been abused (3) had lower levels of serotonin with impaired functioning and increased suicidal risk (4). Much research inquiry remains to be done.
The neurobiological evidence for suicide presents a complex picture of multifactorial possibilities. This includes the real possibility of neurobiological components at least in some cases. As noted, individuals who commit suicide may have neurobiological changes occurring in their bodies that they are not even aware of at the time of the suicide. As noted, some survivors of the suicide of a loved one hold themselves responsible for not having done more to prevent it. It is hoped those who hold themselves responsible for someone’s suicide will understand that suicide is a complex event with possible neurobiological factors present that may impair free choice as we usually understand that term. Holding oneself responsible for not doing more to prevent it, when it may have been a biological event—and that likely nothing more could have been done given our current state of medical knowledge—compounds the loss.
References
3 Flannery, R. B. Jr. Preventing Youth Violence Before It Begins. Riverdale, NY: America Mental Health Fdn, 2022.
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Dr. Raymond B. Flannery Jr., Ph.D. FACLP, is an internationally recognized scholar and lecturer on the topics of violence, victimization, and stress management. Dr. Flannery is available for lectures and workshops, all types of groups, and may be reached at The American Mental Health Foundation: elomke[at]americanmentalhealthfoundation.org.
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