Will to die: brain behind pulling the trigger

Bc. Sofiya Valeeva

The Faculty of Social Sciences, Charles University in Prague.

E-mail: Sofiya.L.valeeva@gmail.com.


Suicide and the Brain

Despite suicide being a major health concern worldwide, its neurobiology is far from being clearly defined. Even with technological advances in treating psychiatric disorders, suicide rates are progressively increasing.[1]

According to the definition by the World Health Organization, suicide is the act of killing oneself intentionally.[2] In Diagnostic and Statistical Manual of Mental Disorders (DSM-5) it is considered to be a symptom of various psychiatric conditions (e.g. depression, Borderline Personality Disorder, psychosis, anxiety, etc.), not a separate diagnosis.[3] Suicidality in a more general sense can describe suicidal attempts, plans, and ideations.[4]

There are a number of stressors associated with suicidal behaviour ranging from personal and financial problems to full blown psychiatric disorders. Stress in general is widely known as one of the risk factors leading to suicide behaviour.[5]  It is, however, worth noting that only a small percentage of individuals faced with these stressors would demonstrate suicidal behaviour.[6] There are three major cognitive characteristics that can be attributed to suicidal patients: “(1) an attentional bias to particular life events reflecting signals of defeat (‘loser’ status), (2) the sense of insufficient capacity to solve problems and (3) the absence of prospective anticipation to problems, leading to hopelessness.”[7]

Research suggests that cognitive functioning in suicidal patients is different compared to healthy controls or even those with, say, depression but no suicidality in their medical history. This raises the question of neurobiological bases for suicide behaviour.

From the neuroanatomical point of view, there are certain brain areas associated with higher vulnerability to suicidal behaviour. Research suggests that frontal, temporal, and parietal cortexes are heavily involved and dysfunctions in those areas are associated with elevated risks of suicidal behaviour.[8] Most current neuroimaging reviews confirm the involvements of the dorsolateral and orbitofrontal cortexes, as well as left superior temporal gyrus, rectal gyrus, and caudate nucleus. These areas are involved in processing executive functions, emotions, and rewards. Dysfunctions in the areas mentioned above are associated with decreased support seeking and ability to regulate behaviour, as well as increased levels of hopelessness and impulsivity in suicidal patients among other things.[9]

Magnetic Resonance Imaging studies have revealed higher prevalence of hyperintensities of white and grey matter in the frontal, temporal, and parietal lobes of suicide patients, as well as decreased volumes in both the frontal and temporal lobes. This allows us to speculate that suicidal behaviour is related to hyperintensities of grey matter and reduction of volume in cortical and subcortical structures, which might mean disruption of crucial neuroanatomic pathways leading to impaired decision-making and predisposition to impulsivity, resulting in higher risk of suicide attempts.[10]

Functional imaging has revealed prefrontal dysfunction, particularly in orbitofrontal cortex that is involved in response inhibition and its impairment might lead to reduction of impulse control and problem-solving abilities, as well as increased proneness to act on negative emotions and focus on certain negative aspects of life.[11]

Another brain area that is associated with suicidal behaviour is hippocampus, which is concerned with cognition[12] and is primarily affected by stress[13]. There is some evidence to support that neurotrophins[14] are regulated in response to stress.[15]

Neurochemical aspects of suicide are not well known, yet there has been evidence stacking up in support of the notion that neurotrophins, that are involved in directing brain growth and are essential for maintenance of neural functions, have a lot to do with suicidal behaviour and its pathophysiological aspects.[16]

A study done by Banerjee et al. (2013) revealed that expression of neurotrophins and their cognitive receptors (TrkB and TrkA) in hippocampal region of the postmortem brains of suicide victims was reduced compared to controls. This strongly suggests that such molecules as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) which are crucial in mediating survival of the cells, plasticity of synapses, as well as other physiological functions, are involved in pathophysiology of suicidal behaviour.[17] Authors suggest that reduced expression of neurotrophins might be linked to structural abnormalities in cortical and hippocampal brain areas as well as reduced plasticity, which is supported by other studies.[18] ٫[19]

Despite the fact that underlying causes and pathologic mechanisms of suicide remain unclear, there is a certain determinism to it due to the brain involvement, which raises the question of what role free will plays in suicide. This is discussed in the following sections.

Determinism and the concept of free will

Physical determinism has been proven to be rather problematic, since the effects of genetic and environmental determinism are only partial, while physical determinism itself is considered to have total effects.

Approximately 6.2×109 bits of information is contained in human genome, while the amount of information that can de facto be used is even smaller. This implies that the genome does not contain enough information to specify the connectivity of 1011 neurons and hundreds of their synaptic contacts. Meaning that the human brain is far too complex to be genetically determined. This is well illustrated by the phenotypical differences between isogenic[20] lower animals like daphnia[21], as well as morphological brain differences and variations in psychological characteristics and intellectual abilities in monozygotic twins.[22]

Traditionally, differences between isogenic organisms are associated with external environmental factors ranging from subtle differences between embryos in the womb[23] to upbringing. The combination of genetic and environmental determination is often considered a good enough explanation for population variations among academics. However, if we consider processes that occur at the cellular and molecular level, there seems to be a possibility to question the deterministic approach. Scholars like Clarke (2010) argue that developmental noise (chance events) beyond the control of genes and environment have sufficient influence on brain development, which results in differences between individuals.[24]

For instance, filopodia, which are projections that extend from the ends of axon and dendrites, are constantly growing and changing directions, which requires some trial and error. They recognize molecular guidance molecules as they are trying to reach the correct region of the brain, yet not all of them make it to the desired destination. Some grow to the wrong part of the brain (up to 40%), while others might even grow to the wrong side of it (up to 1%). This may lead to axon degeneration or even death of the neuron due to the brain trying to eliminate the error. As Clarke (2010) puts it, our brain development is not determined “by a rigidly prespecified programme, but by a more approximate process involving imprecision everywhere, gross mistakes occasionally, and elimination of faulty elements at various inspection points along the cellular production line.” [25] Which further supports the notion of genetic specification being only an approximation.

Laws of nature, apart from minor inconsistencies on quantum level, are deterministic, which raises a question of compatibility between the theory of free will and the deterministic universe, considering that our brains are governed by the laws of physics.[26] Can we really be held accountable for our actions and choices if they were determined long before we made them? Is there freedom of choice if our behaviour is determined by the laws of chemistry and physics?

Philosophers arguing the existence of free will can be roughly divided into two major groups in regards to their opinion on determinism: compatibilists and incompatibilists.[27]

Compatibilists like Hobbes, Hume, and Spinoza operate on the premise that free will and responsibility for one’s actions are perfectly compatible with determinism, while incompatibilists can be further divided into two categories: libertarians and hard determinists. Libertarians like Kant argue that existence of free will requires indeterminism in nature and brain function, hence deny physical predictability and affirm the existence of free will. Hard determinists like Nietzsche, on the other hand, consider free will to be a mere illusion and argue that according to deterministic theory our future, including the future of our brain, is predetermined by our past.[28]

The existence and role of free will has been debated for centuries among the philosophic community.[29] Defining it has proven to be rather problematic, since most philosophers incorporate their own philosophical theories into the definition. Some even dispute the very term, preferring to refer to free will as freedom of action.[30]

Some define free will through a profound connection with God. Others believe that free will means that one’s personal choice on how to behave is not influenced by outside forces – physical, religious or otherwise. That we as humans have a single command center calling the shots.[31]

One’s view of free will is most often determined by one’s opinion regarding the relationship between the mind and the brain, as well as their belief in the existence of a soul. Monists would have a different approach to the subject than dualists, and, would most likely take a more deterministic position. Others that view soul as a separate entity would lean towards indeterminism.[32]

A dualist approach, most popular nowadays, implies that the soul is eternal entity completely separate from our mortal, physical body. The concept is rooted in antient Greek philosophy and was developed by neoplatonists, however, in modern society, it is a part of a Western Christian way of thinking. Funny enough, if we look through the Old Testament, nowhere does it imply this dualistic approach. The most common words that are often translated as ‘soul’ are nephesh (life, vitality) and ruah (spirit). Both can describe an instance of leaving an individual dead, yet none are mentioned to exist separately from the mortal body. In the New Testament there’s also a word psyche that is similar in meaning to nephesh, yet most scholars agree that the New Testament as well puts emphasis on the unity of a man and does not exercise Platonic dualistic approach. As a matter of fact, immortality of the soul is not stated anywhere in the Bible, nor does it propagate the notion of disembodiment.[33]

Nonetheless, the biggest Christian philosophers like St. Augustin, who first started to differentiate between freedom and free will, as well as Luther and Calvin have all been dualists, and the dualistic approach is still popular among modern philosophers and scholars.[34],[35]

Physical determinism and its application on the human brain and, consequently, free will, is a major philosophical problem. In order to combine the concept of freedom with supposed physical determinism, quantum indeterminism[36] and/or chaos theory[37] are used to work around the physical predictability

There have been quite a few attempts to apply quantum indeterminism to the concept of free will. One of these attempts was made by Eccles, who proposed that Heisenberg’s uncertainty principle can be applied to synaptic function. Another hypothesis was initially presented by Penrose and Hameroff (‘brain as quantum computer’ theory). It proposed that quantum indeterminism has an effect on microtubules inside axons.[38] Both theories tried their best to prove the existence of indeterminism at the brain level in an otherwise deterministic physical model, yet failed to do so by being proven faulty or undetermined aspects being too small to influence major brain activity.

Some scientists add chaos theory to the equation in order to justify the existence of free will. There’s been enough evidence to prove that chaos, in fact, occurs in brain activity. The premise is that it is capable of amplifying the indeterminism available from the quantum theory paradigm, hence, even if the brain activity is influenced very slightly, chaotic dynamics are able to amplify them enormously. This provides some scientists the base to argue that there is a possibility for the non-physical mind to influence the brain and alter our behavior.[39]

There are, however, some significant problems with the baseline logic of this approach that allow one to dispute the very existence of quantum chaos. The major problem being the mathematical prediction of quantum suppression of chaos. Theoretically speaking, there is a possibility of it being suppressed by quantum decoherence through the interaction between the environment and quantum system.[40] However, fundamental indeterminism, which is needed to prove the existence of free will, can not be provided by quantum chaos since, in this case, the environment must be considered as an external element to the quantum system, which will not be subject to decoherence. On top of that, the decision-making process under the chaos theory would be extremely sensitive to minor events like blood pressure or irrelevant neural input.[41]

Conclusion

The indeterministic concept of free will raises some major question when challenged with deterministic model of our brain. There is ongoing research regarding this topic but, the possibility of us humans making free choices that are not rooted in physics and chemistry is rather slim; especially when it comes to suicidal behaviour that seems to be governed by the faulty brain structures. Despite some pathological mechanisms of suicide being unclear, there is little doubt in my mind that free will plays little role in deciding to kill oneself if our brain dictates one to do so.

Summary:

The following article reviews current research regarding the connection between suicidal behaviour and functional and structural abnormalities of the brain. It also deals with the question of free will in suicidal behaviour in particular, and the possibility of us making free choices in general. It compares the indeterministic concept of free will against the deterministic model of our nervous system and tries to answer the question whether or not it is possible to choose suicide freely.

Shrnutí:

Následující článek shrnuje aktualní výzkum vztahů mezi sebevražedným chováním a funkčními a strukturálními abnormalitami mozku. Zabývá se také otázkou svobodné vůle zejména v oblasti sebevražedného chování a možností obecně volného rozhodování. Článek porovnává indeterministický pojem svobodné vůle proti deterministickému modelu našeho nervového systému a pokouší se odpovědět na otázku, zda možné zvolit sebevraždu volně.

Bibliography

Alfonso, Julieta, Guido D Pollevick, Marieke G Van Der Hart, Gabriele Flügge, Eberhard Fuchs and Alberto CC Frasch. 2004. „Identification of Genes Regulated by Chronic Psychosocial Stress and Antidepressant Treatment in the Hippocampus.“ European Journal of Neuroscience 19(3):659-66.

Banerjee, Ritabrata, Anup K Ghosh, Balaram Ghosh, Somnath Bhattacharya and Amal C Mondal. 2013. „Suicide: Neurochemical Approaches.“ BRAIN. Broad Research in Artificial Intelligence and Neuroscience 4(1-4):97-104.

Bani-Fatemi, Ali, Samia Tasmim, Ariel Graff, Philip Gerretsen, John Strauss, Nathan Kolla, Gianfranco Spalletta and Vincenzo De Luca. 2018. „Structural and Functional Alterations of the Suicidal Brain: An Updated Review of Neuroimaging Studies.“ Psychiatry Research: Neuroimaging.

Berry, Michael V. 2001. „Chaos and the Semiclassical Limit of Quantum Mechanics (Is the Moon There When Somebody Looks?).“ Quantum Mechanics: Scientific perspectives on divine action 41.

Clarke, Peter Gh. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

Cosman, Doina. 2018. „Suicide–Freedom or Constraint? How Free Will Works in Autolysis.“ Romanian Journal of Artistic Creativity 6(3).

Desmyter, Stefanie, Cornelis Van Heeringen and Kurt Audenaert. 2011. „Structural and Functional Neuroimaging Studies of the Suicidal Brain.“ Progress in neuro-psychopharmacology and biological psychiatry 35(4):796-808.

Gazzaniga, Michael. 2012. Who’s in Charge?: Free Will and the Science of the Brain: Hachette UK.

Houart, Gérald, Geneviève Dupont and Albert Goldbeter. 1999. „Bursting, Chaos and Birhythmicity Originating from Self-Modulation of the Inositol 1, 4, 5-Trisphosphate Signal in a Model for Intracellular Ca 2+ Oscillations.“ Bulletin of mathematical biology 61(3):507-30.

Jollant, Fabrice. 2016. „Neuroimaging of Suicidal Behavior.“ Pp. 110-22 in Biological Aspects of Suicidal Behavior, Vol. 30: Karger Publishers.

Miguel-Hidalgo, José Javier and Grazyna Rajkowska. 2002. „Morphological Brain Changes in Depression.“ CNS drugs 16(6):361-72.

Rowe, Christopher J and Sarah Broadie. 2002. Nicomachean Ethics: Oxford University Press, USA.

Sala, M, J Perez, P Soloff, S Ucelli Di Nemi, E Caverzasi, JC Soares and P Brambilla. 2004. „Stress and Hippocampal Abnormalities in Psychiatric Disorders.“ European Neuropsychopharmacology 14(5):393-405.

Sheline, Yvette I, Mokhtar H Gado and Helena C Kraemer. 2003. „Untreated Depression and Hippocampal Volume Loss.“ American Journal of Psychiatry 160(8):1516-18.

Suicide, WHO Preventing. 2014. „A Global Imperative.“ World Health Organization.

Sweatt, J David. 2004. „Hippocampal Function in Cognition.“ Psychopharmacology 174(1):99-110.

Westrin, Å. 2000. „Stress System Alterations and Mood Disorders in Suicidal Patients. A Review.“ Biomedicine & pharmacotherapy 54(3):142-45.

Poznámky

[1] Banerjee, Ritabrata, Anup K Ghosh, Balaram Ghosh, Somnath Bhattacharya and Amal C Mondal. 2013. „Suicide: Neurochemical Approaches.“ BRAIN. Broad Research in Artificial Intelligence and Neuroscience 4(1-4):97-104.

[2] Suicide, WHO Preventing. 2014. „A Global Imperative.“ World Health Organization.

[3] Desmyter, Stefanie, Cornelis Van Heeringen and Kurt Audenaert. 2011. „Structural and Functional Neuroimaging Studies of the Suicidal Brain.“ Progress in neuro-psychopharmacology and biological psychiatry 35(4):796-808.

[4] Bani-Fatemi, Ali, Samia Tasmim, Ariel Graff, Philip Gerretsen, John Strauss, Nathan Kolla, Gianfranco Spalletta and Vincenzo De Luca. 2018. „Structural and Functional Alterations of the Suicidal Brain: An Updated Review of Neuroimaging Studies.“ Psychiatry Research: Neuroimaging.

[5] Westrin, Å. 2000. „Stress System Alterations and Mood Disorders in Suicidal Patients. A Review.“ Biomedicine & pharmacotherapy 54(3):142-45.

[6] Bani-Fatemi, Ali, Samia Tasmim, Ariel Graff, Philip Gerretsen, John Strauss, Nathan Kolla, Gianfranco Spalletta and Vincenzo De Luca. 2018. „Structural and Functional Alterations of the Suicidal Brain: An Updated Review of Neuroimaging Studies.“ Psychiatry Research: Neuroimaging.

[7] Desmyter, Stefanie, Cornelis Van Heeringen and Kurt Audenaert. 2011. „Structural and Functional Neuroimaging Studies of the Suicidal Brain.“ Progress in neuro-psychopharmacology and biological psychiatry 35(4):796-808.

[8] Jollant, Fabrice. 2016. „Neuroimaging of Suicidal Behavior.“ Pp. 110-22 in Biological Aspects of Suicidal Behavior, Vol. 30: Karger Publishers.

[9] Bani-Fatemi, Ali, Samia Tasmim, Ariel Graff, Philip Gerretsen, John Strauss, Nathan Kolla, Gianfranco Spalletta and Vincenzo De Luca. 2018. „Structural and Functional Alterations of the Suicidal Brain: An Updated Review of Neuroimaging Studies.“ Psychiatry Research: Neuroimaging.

[10] Desmyter, Stefanie, Cornelis Van Heeringen and Kurt Audenaert. 2011. „Structural and Functional Neuroimaging Studies of the Suicidal Brain.“ Progress in neuro-psychopharmacology and biological psychiatry 35(4):796-808.

[11] Ibid.

[12] Sweatt, J David. 2004. „Hippocampal Function in Cognition.“ Psychopharmacology 174(1):99-110.

[13] Sala, M, J Perez, P Soloff, S Ucelli Di Nemi, E Caverzasi, JC Soares and P Brambilla. 2004. „Stress and Hippocampal Abnormalities in Psychiatric Disorders.“ European Neuropsychopharmacology 14(5):393-405.

[14] Proteins concerned with neuron function and development that can signal particular cells to survive, differentiate, grow, etc.

[15] Alfonso, Julieta, Guido D Pollevick, Marieke G Van Der Hart, Gabriele Flügge, Eberhard Fuchs and Alberto CC Frasch. 2004. „Identification of Genes Regulated by Chronic Psychosocial Stress and Antidepressant Treatment in the Hippocampus.“ European Journal of Neuroscience 19(3):659-66.

[16] Banerjee, Ritabrata, Anup K Ghosh, Balaram Ghosh, Somnath Bhattacharya and Amal C Mondal. 2013. „Suicide: Neurochemical Approaches.“ BRAIN. Broad Research in Artificial Intelligence and Neuroscience 4(1-4):97-104.

[17] Ibid.

[18] Sheline, Yvette I, Mokhtar H Gado and Helena C Kraemer. 2003. „Untreated Depression and Hippocampal Volume Loss.“ American Journal of Psychiatry 160(8):1516-18.

[19] Miguel-Hidalgo, José Javier and Grazyna Rajkowska. 2002. „Morphological Brain Changes in Depression.“ CNS drugs 16(6):361-72.

[20] Genetically identical.

[21] Water fleas.

[22] Clarke, Peter Gh. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

[23] One twin can be exposed to more nutrition due to a richer blood supply.

[24] Clarke, Peter Gh. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

[25] Ibid.

[26] Ibid.

[27] It is worth noting that there are philosophers like Strawson that deny compatibility of both subcategories with the theory of free will, but the format of the article does not allow us to go into more detail.

[28] Ibid.

[29] Rowe, Christopher J and Sarah Broadie. 2002. Nicomachean Ethics: Oxford University Press, USA.

[30] Clarke, Peter Gh. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

[31] Gazzaniga, Michael. 2012. Who’s in Charge?: Free Will and the Science of the Brain: Hachette UK.

[32] Clarke, Peter Gh. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

[33] Ibid.

[34] Cosman, Doina. 2018. „Suicide–Freedom or Constraint? How Free Will Works in Autolysis.“ Romanian Journal of Artistic Creativity 6(3).

[35] Clarke, Peter GH. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

[36] Physical system cannot be described completely, hence no outcome is certain and probabilistic.

[37] Describes the behaviour of complex nonlinear dynamical systems that are highly sensitive to subtle changes under certain conditions, which can lead to major consequences within the system. The behavior of such a system seems random, even if the model describing the system is deterministic.

[38] It was not intended to prove the existence of free will, yet some philosophers adapted it to serve that purpose.

[39] Houart, Gérald, Geneviève Dupont and Albert Goldbeter. 1999. „Bursting, Chaos and Birhythmicity Originating from Self-Modulation of the Inositol 1, 4, 5-Trisphosphate Signal in a Model for Intracellular Ca 2+ Oscillations.“ Bulletin of mathematical biology 61(3):507-30.

[40] Berry, Michael V. 2001. „Chaos and the Semiclassical Limit of Quantum Mechanics (Is the Moon There When Somebody Looks?).“ Quantum Mechanics: Scientific perspectives on divine action 41.

[41] Clarke, Peter GH. 2010. „Determinism, Brain Function and Free Will.“ Science & Christian Belief 22(2).

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