Biological bases of suicidal behaviours: A narrative review

Abstract

In humans, suicide overrides the basic instinct of survival that is common to the vast majority of known life forms. This phenomenon has frightened and fascinated philosophers throughout history. This virtually exclusively human behaviour has been and still is a major issue worldwide, thus explaining its place first in religious and philosophical doctrines, then in sociology and philosophy, and currently in biology and medicine.

Suicidal and non-suicidal self-injurious behaviour in patients with bipolar disorder and comorbid attention deficit hyperactivity disorder after initiation of central stimulant treatment: a mirror-image study based on the LiSIE retrospective cohort

“…Suicidal behaviour has been linked to impulsive aggression, 59 impaired executive function and inhibition, 60 and altered decision-making. 61 These factors have also been observed in patients with BD. Impaired executive function, particularly impaired decision making and impulsivity, 62 – 66 has been linked to an increased risk of suicidal and NSSI behaviour.…”

Commentary: Psychedelic Psychiatry's Brave New World

“…Several studies reported alterations of the serotoninergic (e.g., serotonin depletion), glutamatergic (e.g., alteration of the kynurenine pathway), and inflammatory systems (e.g., increased levels of proinflammatory cytokines), as well as neuroplasticity [e.g., low levels of brain-derived neurotrophic factor (BDNF)] in SB ( 6 ). Psilocybin is rapidly metabolized into its active metabolite psilocin that is a serotoninergic agonist with high affinity for 5-HT2A receptors (5-HT2AR) ( 1 ).…”

“…Psilocybin intake results in a rapid increase in 5-HT2AR activity that might lead to higher BDNF expression and consequently to major synaptic changes ( 7 ) and might promote neuroplasticity. Postmortem studies showed that 5-HT2AR availability is increased in the brain of suicide victims, possibly due to genetic variations or compensatory mechanisms ( 6 ). Therefore, psilocybin-positive effect on neuroplasticity and the serotoninergic system could contribute to compensate SB-related impairment of these systems.…”

“…Therefore, psilocybin-positive effect on neuroplasticity and the serotoninergic system could contribute to compensate SB-related impairment of these systems. Second, similarly to ketamine, which reduces SI ( 6 ), psilocybin is a modulator of glutamatergic activity in prefrontal circuits. A common mechanism of action through modulation of glutamatergic transmission (leading to neuroplastic adaptations) could underlie the antisuicidal action of psilocybin and ketamine ( 2 ).…”

“…It is assumed that in psychedelic therapy, cognitive flexibility, and promotion of acceptance increase in response to psilocybin intake, reinforced by the slogan: “trust, let go, and be open,” but could also continue for a long time after the treatment ( 8 ). This effect might be particularly relevant for suicidal patients who are characterized by altered decision-making, reduced cognitive flexibility, and poor problem-solving ability ( 6 ). Furthermore, SB could be considered the most extreme expression of experiential avoidance.…”