Quick—which screening test or instrument has greater specificity for the target condition: the PSA (prostate specific antigen) test for prostate cancer, or the BSDS (Bipolar Spectrum Diagnostic Scale), for bipolar disorders?
Wait, one more question: Which physicians are more likely to agree with one another regarding a diagnosis: 2 radiologists inspecting a renal angiogram for arterial stenosis; or 2 psychiatrists using a structured interview to assess a patient for possible major depression?
Those of you who are used to “trick questions” on Board exams will probably not be surprised that the answers are, respectively, “The BSDS” (specificity 0.93 vs 0.33 for PSA); and “the 2 psychiatrists.” (kappa [inter-rater agreement]= 0.73 vs 0.43 for radiologists)1-5 (Disclosure: The BSDS was devised by the present author, then refined and field-tested by Dr Nassir Ghaemi and colleagues; it is available free of charge on this website).
What does this very selective demonstration prove? Not much. Can we conclude that psychiatry is more “scientific” than urology or radiology? Hardly. The exercise was presented mainly to roil the waters surrounding those comfortable cynics who insist that psychiatry is not “scientific” or a “real science.” The numerous controversies surrounding the DSM5—covered at length in this journal—seem to have brought these critics of psychiatry out in force.
Whatever the failings of the DSM5, the notion that psychiatry is not a science is profoundly wrong. Proponents of that view persistently confuse science with “logical positivism”—-a largely discredited form of scientific fundamentalism6—and misunderstand the nature of the scientific enterprise. In fact, my gambit involving PSAs and angiograms was itself a bit misleading. To the extent we can identify the foundational principle of science, it has little to do with lab tests, and a great deal to do with the scientist’s mind-set and methodology.
To be sure, philosophers of science point out that there may be no single, valid definition of “science” or of the “scientific method.” As philosopher Samir Okasha puts it, “…science is a heterogeneous activity, encompassing a wide range of different disciplines and theories. It may be that they share some fixed set of features that define what it is to be a science, but it may not.”7
And so, to assert what science “is” or “is not” with great confidence—-or to declare categorically which medical specialties constitute “real science”—is to over-reach in one’s epistemology by a considerable stretch. This doesn’t mean that we are left utterly adrift, however, without even a notional definition of science. Recently, the British Science Council spent a full year developing a definition of “science.” Their work-product is succinct and yet radically insightful:
"Science is the pursuit of knowledge and understanding of the natural and social world following a systematic methodology based on evidence."8
Good heavens! No lab tests required for science? No MRIs? No demonstrations of cellular pathology? Why, if this barmy British Science Council has its way, fields as diverse as physics, meteorology, linguistics, and anthropology would qualify as sciences! And, yes, without question--so would psychiatry.
Let’s be clear: not all science is physical science. Although psychiatry is nowadays associated with “biological psychiatry”--with PET scans, MRIs, neurotransmitters and the like--the domain of psychiatry is broader, deeper, and more pluralistic. As my colleagues Nassir Ghaemi MD9 and Michael A. Schwartz MD10 have argued, psychiatry is fundamentally a science of meaning. Wiggins and Schwartz define “meanings” as “…mental processes and their intended objects.”10(p.49)
We acquire evidence of our patient’s mental processes through precisely the “systematic methodology” required by the Science Council’s definition: we take a personal and family history; we perform a mental status exam; we observe our patient’s facial expression, affect, mannerisms, and speech. And we ask countless questions of the patient, aimed at eliciting deeper levels of meaning within the felt experience of the patient’s world. In some instances, we supplement these “office based” methods with projective or neuropsychological testing. In selected cases, we ask the patient to complete screening questionnaires or (rarely) to participate in a structured clinical interview. And, consistent with our pluralistic model of “mind,” we order appropriate laboratory and somatic tests to rule out underlying medical or neurological disorders.
We then form hypotheses based on these methods,regarding the patient’s psychopathology, personality structure, and clinical diagnosis. We test these hypotheses against subsequent observations, and—if we detect inconsistencies—we revisit our initial formulation. What Okasha identifies as “some of the main features of scientific inquiry”7(p. 125)—induction, experimental testing, observation, theory construction—are all part of psychiatric methodology. In short, psychiatry is well within the orthodox definition of “science.”
Do the methods of the DSM5 conform to this paradigm? That is a more complicated question, since the DSM5 work groups do not obtain data in the direct, observational way clinicians do. However, if science is “the pursuit of knowledge and understanding of the natural and social world following a systematic methodology based on evidence", the DSM5 process is arguably working within the broad framework of science. Like all such endeavors, the DSM5 process is buffeted by external forces and pressures that may mar its objectivity and undermine its science. We shall have to wait and see. But whatever the merits or flaws of the DSM5, psychiatry as a profession remains a science—not a physical, but a human science, grounded in a pluralistic understanding of our patients’ “meanings.”
1. Ghaemi S, Miller CJ, Berv DA et al: Sensitivity and specificity of a new bipolar spectrum diagnostic scale. J Affect Disord. 2005 Feb;84(2-3):273-7.
2. Hoffman RM, Gilliland FD, Adams-Cameron M, et al: Prostate-specific antigen testing accuracy in community practice . BMC Fam Pract. 2002; 3: 19.
3. Schreij G, de Haan MW, Oei TK, et al. Interpretation of renal angiography by radiologists. J Hypertens 1999;17(12 Pt 1):1737–41.
4. Ruskin PE, Reed S, Kumar R et al. Reliability and acceptability of psychiatric diagnosis via telecommunication and audiovisual technology. Psychiatr Serv 1998;49:1086–8.
5. Pies R: How “Objective” Are Psychiatric Diagnoses? (Guess Again) PsychiatryMMC, 2007. Accessed at: http://www.psychiatrymmc.com/how-%E2%80%9Cobjective%E2%80%9D-are-psychiatric-diagnoses-guess-again/.
6. Hanfling O: Logical Positivism. In: Philosophy of science, logic, and mathematics in the twentieth century, by Stuart Shanker. Volume 9 of the Routledge History of Philosophy, New York, Routledge, 1996. pp. 193-213.
7. Okasha S: Philosophy of Science. Oxford University Press, 2002, pp. 16-17.
9. Ghaemi SN: The Concepts of Psychiatry, Baltimore, Johns Hopkins University Press, 2003, pp. 90-93.
10. Wiggins O.P., Schwartz MA: Is there a science of meaning? Integrative Psychiatry 1991;7:48-53.