Depression and suicide are natural kinds: Implications for physician-assisted suicide

https://doi.org/10.1016/j.ijlp.2013.06.013Get rights and content

Abstract

In this article, I argue that depression and suicide are natural kinds insofar as they are classes of abnormal behavior underwritten by sets of stable biological mechanisms. In particular, depression and suicide are neurobiological kinds characterized by disturbances in serotonin functioning that affect various brain areas (i.e., the amygdala, anterior cingulate, prefrontal cortex, and hippocampus). The significance of this argument is that the natural (biological) basis of depression and suicide allows for reliable projectable inferences (i.e., predictions) to be made about individual members of a kind. In the context of assisted suicide, inferences about the decision-making capacity of depressed individuals seeking physician-assisted suicide are of special interest. I examine evidence that depression can hamper the decision-making capacity of individuals seeking assisted suicide and discuss some implications.

Introduction

What kind of thing is classified by the term ‘suicide’? Is it a medical condition? Or is suicide better understood as a social (or socially constructed) phenomenon? This article addresses these questions by focusing on the question of whether depression and suicide are natural kinds. I subsequently examine what bearing these issues regarding the naturalness of suicide have on the thorny issue of assisted suicide.

A high proportion of patients who request physician-assisted suicide are suffering from depression or present depressive symptoms (Levene & Parker, 2011). This circumstance raises important questions about how depression affects individuals' judgments about ending their lives, and in particular, whether depression hampers individuals' capacity to make competent decisions about assisted suicide. Moreover, the high prevalence of depression among individuals seeking physician-assisted suicide highlights the importance of issues regarding the specific ways in which depression can alter patients' decision-making process and the extent to which the kinds of depression that are a precursor to suicide are treatable.

The article proceeds as follows. In 2 Natural kinds in psychiatry, 3 Are depression and suicide natural kinds?, I examine questions concerning the naturalness of depression and suicide. In Section 2, I critically examine the views of Thomas Szasz and Ian Hacking who offer different reasons for rejecting the existence of natural kinds in psychiatry. I subsequently propose a positive theoretical account of natural kinds in psychiatry that maintains that some mental disorders are natural kinds insofar as members of a kind share the same biological causal structure. More specifically, natural kinds in psychiatry (e.g., schizophrenia, bipolar disorder) are stable objects of classification whose characteristic signs are determined by networks of stable biological mechanisms. Analyses of Szasz and Hacking fail to establish that these natural kinds (i.e., mechanistic property cluster kinds) do not exist. In Section 3, I argue that depression and suicide are natural kinds because they are classes of abnormal behavior associated with serotonin dysfunction in various brain structures (i.e., the amygdala, anterior cingulate, prefrontal cortex, and hippocampus). In Section 4, I consider the implications of this analysis for assisted suicide. My focus is on questions concerning the extent that depression hampers individuals' capacity to make sound decisions and the potential to treat more severe forms of depression.

Section snippets

Natural kinds in psychiatry

In philosophy of science, the distinction between natural kinds and artificial kinds refers to a distinction between kinds (or classes) of things that are discovered and invented respectively (see Bird & Tobin, 2010). Natural kinds are classes of naturally occurring objects, properties, or processes that exist independent of and are discovered by classifiers (e.g., electrons, gold, H20, fish). By contrast, artificial kinds are classes of objects that are imposed on nature and invented by

Are depression and suicide natural kinds?

In the following section, I argue that depression and suicide are natural kinds insofar as they are classes of (abnormal) behavior that are underwritten by stable neurobiological mechanisms. In articulating this argument, I presuppose a diathesis-stress model wherein individuals may inherit a neurobiological vulnerability to depression and suicide (Mann, Waternaux, Haas, & Malone, 1999). In this model, individuals who inherit a susceptibility (diathesis) to depression and suicide are more

Implications for physician-assisted suicide

Issues regarding the naturalness of depression and suicide are highly relevant for assisted suicide. In the context of physician-assisted suicide, the fact that depression is a natural kind is significant because it is precisely the natural (i.e., biological) basis of depression that allows physicians to make projectable inferences about patients who are considering assisted suicide. As discussed in the second section of this article, natural kind terms (e.g., ‘depression,’ ‘schizophrenia’) are

Conclusion

In this article, I argued that depression and suicide are natural kinds insofar as they are classes constituted by distinct neurobiological mechanisms, e.g., deficient serotonin activity due to insensitive 5-HT receptors. The significance of this argument is that the natural (biological) basis of these classes allows for projectable inferences to be made about members of a kind. In the context of assisted suicide, inferences concerning the decision-making competence of depressed patients

Acknowledgments

I am grateful to Kate Padgett-Walsh, Paul Thagard, Stephen Biggs, Inmaculada de Melo-Martín, and an anonymous referee of this journal for very helpful comments and suggestions on earlier drafts of this article. I would also like to express my gratitude to Ian Hacking, Christopher DiTeresi, and Bill Wimsatt for earlier discussions that helped to shape my views on natural kinds in psychiatry.

References (156)

  • W. Bechtel et al.

    Discovering complexity: Decomposition and localization as strategies in scientific research

    (1993)
  • A.T. Beck et al.

    Hopelessness and suicidal behavior: An overview

    Journal of the American Medical Association

    (1975)
  • H. Beebee et al.

    Are psychiatric kinds ‘real’?

    European Journal of Analytic Philosophy

    (2010)
  • C. Benkelfat et al.

    Mood-lowering effect of tryptophan depletion: Enhanced susceptibility in young men at genetic risk for major affective disorders

    Archives of General Psychiatry

    (1994)
  • A. Bird et al.

    Natural kinds

  • C. Boorse

    On the distinction between disease and illness

    Philosophy and Public Affairs

    (1975)
  • C. Boorse

    What a theory of mental health should be

    Journal for the Theory of Social Behaviour

    (1976)
  • C. Boorse

    Health as a theoretical concept

    Philosophy of Science

    (1977)
  • C. Boorse

    A rebuttal on health

  • R. Boyd

    Observations, explanatory power, and simplicity: Toward a non-Humean account

  • R. Boyd

    How to be a moral realist

  • R. Boyd

    What realism implies and what it does not

    Dialectica

    (1989)
  • R. Boyd

    Realism, approximate truth, and philosophical method

  • R. Boyd

    Realism, anti-foundationalism and the enthusiasm for natural kinds

    Philosophical Studies

    (1991)
  • R. Boyd

    Homeostasis, species, and higher taxa

  • R. Boyd

    Realism, natural kinds, and philosophical methods

  • W. Breitbart et al.

    Interest in physician-assisted suicide among ambulatory HIV-infected patients

    The American Journal of Psychiatry

    (1996)
  • W. Breitbart et al.

    Depression, hopelessness, and desire for hastened death in terminally ill patients with cancer

    Journal of the American Medical Association

    (2000)
  • D.A. Brent et al.

    Suicidal behavior runs in families: A controlled family study of adolescent suicide victims

    Archives of General Psychiatry

    (1996)
  • G.K. Brown et al.

    Risk factors for suicide in psychiatric outpatients: A 20-year prospective study

    Journal of Consulting and Clinical Psychology

    (2000)
  • W.E. Bunney et al.

    Further evaluation of urinary 1-hydroxycorticosteroids in suicidal patients

    Archives of General Psychiatry

    (1969)
  • N.R. Carlson

    Foundations of physiological psychology

    (2008)
  • H.M. Chochinov et al.

    Desire for death in the terminally ill

    The American Journal of Psychiatry

    (1995)
  • M. Cholbi

    Suicide: The philosophical dimensions

    (2011)
  • M. Cholbi

    Suicide

  • R. Cooper

    Classifying madness: A philosophical examination of the Diagnostic and Statistical Manual of Mental Disorders

    (2005)
  • R. Cooper

    Psychiatry and philosophy of science

    (2007)
  • C.F. Craver et al.

    Discovering mechanisms in neurobiology: The case of spatial memory

  • P. Cuijpers et al.

    Are psychological and pharmacologic interventions equally effective in the treatment of adult depressive disorders? A meta-analysis of comparative studies

    The Journal of Clinical Psychiatry

    (2008)
  • H. Damasio et al.

    The return of Phineas Gage: Clues about the brain from the skull of a famous patient

    Science

    (1994)
  • N. Daniels

    Health-care needs and distributive justice

    Philosophy and Public Affairs

    (1981)
  • N. Daniels

    Just health care

    (1985)
  • N. Daniels

    Just health: Meeting health needs fairly

    (2008)
  • R.J. Davidson et al.

    Depression: Perspectives from affective neuroscience

    Annual Review of Psychology

    (2002)
  • A. Degl'Innocenti et al.

    Executive deficits in major depression

    Acta Psychiatrica Scandinavica

    (1998)
  • P.L. Delgado

    Depression: The case for a monoamine deficiency

    The Journal of Clinical Psychiatry

    (2000)
  • P.L. Delgado et al.

    Serotonin function and the mechanism of antidepressant action: Reversal of antidepressant induced remission by rapid depletion of plasma tryptophan

    Archives of General Psychiatry

    (1990)
  • Depression Guideline Panel

    Depression in primary care: Volume 2. Treatment of major depression

    (1993)
  • G. Dieserud et al.

    Predicating repetition of suicide attempt: A prospective study of 50 suicide attempters

    Archives of Suicide Research

    (2003)
  • J. Dupré

    Natural kinds and biological taxa

    Philosophical Review

    (1981)
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