Cholera in 1849 and the Biopsychosocial Model: Historical Analysis or Anachronism?

Cholera in 1849 and the Cholera in 1849 and the Biopsychosocial Model: Biopsychosocial Model:

Historical Analysis or Historical Analysis or Anachronism?Anachronism?

The Snowflakes of MSU:Peter Vinten-Johansen

Howard BrodyNigel Paneth

Steve RachmanMichael Rip

The ArgumentThe ArgumentOne can draw useful analogies

between: – Today’s biopsychosocial model of

human health, and – The scientific approaches used by John

Snow to study both cholera transmission and inhalation anesthesia in 1846-56?

The Argument--IIThe Argument--IIThe BPS modelJohn Snow and his careerMethods of studying anesthesiaMethods of studying cholera

transmissionSnow’s theoretical synthesis (“continuous

molecular changes”)

Engel, 1977: BPS ModelEngel, 1977: BPS ModelSystems (part-whole relations)Multilevel hierarchy (atoms to

biosphere)“Ripple effects” among levelsPatterns of information flow

(feedback loops)Anti-reductionistic

BPS: SourcesBPS: SourcesGeneral systems theory (von

Bertalanffy, Laszlo)– Cybernetics (von Neumann),

information theory, game theory“Holistic” biology (Dubos, Mayr)All grounded in mid-20th-century

thought

John Snow: Early LifeJohn Snow: Early LifeBorn 1813, YorkFather: Laborer/farmerMother: IllegitimateApprentice in Newcastle, 1827-32Cared for coal miners in 1831-32 cholera

epidemic

John Snow: Life (cont.)John Snow: Life (cont.)Newcastle medical school, 1832-34Assistant, Newcastle and Yorkshire,

1834-36Walked to London (via Bath), 1836Hunterian school and Westminster

Hospital, 1836-38MRCS/LSA, 1838General practice, Soho, 1838

John Snow: Later lifeJohn Snow: Later life Active in Westminster Medical Society MD, Univ. of London, 1844 Begins anesthetic research and practice, 1847 On the Mode of Communication of Cholera, 1849 Attends Queen Victoria, 1853, 1857 Broad Street Pump, 1854 President, Medical Society of London, 1855 Completes On Chloroform, 1858 Death of apoplexy, 1858

Snow on EtherSnow on EtherDec. 1846: Sees ether used in LondonJan. 1847: Displays data on relation

between concentration and temperature; working on apparatus

September 1847: Publishes On Ether, 80 cases, describes degrees of anesthesia

How?How?Snow’s research, 1838-46, ideally

prepared him for ether:– Studies of respiration and asphyxia– Studies of chemistry and physics of gases– Properties of inhaled medications and

poisons– Design of new apparatus

Snow’s Approach to EtherSnow’s Approach to EtherChemical level: problem in defining

physics and chemistry e.g. concentration-temperature relationships

Physiological level: animal experiments with different concentrations of gases

Clinical level: correlate bedside observations with animal experiments to predict degrees of anesthesia

Ether and ChloroformEther and Chloroform Define a class of agents with similar properties

(“narcotism”), of which anesthesia only one effect

Calculate precise serum concentrations of agent when inhaled at given concentration in air

Correlate serum concentration with clinically observed effects

Hardly anyone else doing this work in 1847-58

Snow and Cholera: 1848-9Snow and Cholera: 1848-9Cholera must be communicable person-to-

person based on geographic distributionA local affection of alimentary canal;

dehydration produces systemic symptomsAssumed to be inhaled by lungs– why must

this be true?

Snow’s TheorySnow’s TheoryCausal agent of cholera ingestedMultiplies in gut Causes symptoms of disease by irritating

mucous membraneShed in evacuationsHousehold spread: dirty handsArea spread: drinking water

Budd, Brittain, Swayne 1849Budd, Brittain, Swayne 1849

Microscopic particle must cause cholera

Therefore must search for evidence at microscopic level

Identified “cholera fungus”Identification quickly refuted

Snow, 1849Snow, 1849

Molecular

Cellular

Organ/System

Household

Community

“Continuous molecular changes”(self-replication of vital processes)

Can’t identify agent; analogy toova of intestinal worms

Irritation > Diarrhea > Dehydration

Spread by poor hygiene

Spread by contaminated drinkingwater

Snow on Cholera, 1849Snow on Cholera, 1849Move from levels where “collateral

sciences” least developed to levels allowing better tools for investigation

Ova of worms: analogy of functional properties

Cf. “Cholera fungus”: identified a structure but had no idea of function

Cholera Deaths per 10,000 Cholera Deaths per 10,000 Households (Snow, 1855)Households (Snow, 1855)

01020304050607080

Lambeth Co. Southwark & Vauxhall Co.

(first weeks of epidemic)

Snow’s Method, 1849-1855Snow’s Method, 1849-1855Ultimately discovered that statistics was a

sounder basis for investigation than microscopy

Reasoned across levels to deduce likely effects at neighborhood and community levels

Then gathered data to confirm or disconfirm hypotheses

Continuous Molecular Continuous Molecular Changes, 1853Changes, 1853

CMC, 1853CMC, 1853Annual oration to Medical Society of

LondonRare opportunity to speak at theoretical-

speculative levelOpportunity to link (successful)

anesthesia research with (so far rejected) cholera theory

CMC, 1853-- IICMC, 1853-- II“Molecular” = smallest level of

organization, “insensible” (very small) distances between particles acting on each other

“Change” = constant flux at molecular level in either living or non-living matter (common chemical basis of vital and non-vital)

CMC, 1853--IIICMC, 1853--III“Continuous” = molecular processes

peculiar to living things; never commence anew without continuity with previous processes of same type

Combustion/oxidation– a bridging process, exists in both living and non-living matter

Anesthesia: Counter-AffinityAnesthesia: Counter-Affinity

A B

C

C exerts pull on A and prevents A from combining with B,without itself combining

Anesthesia TheoryAnesthesia Theory

C = anesthetic agentA <-> B = oxidation process

responsible for maintaining consciousness and sensation

Reversible interference with normal bodily process

CMC and Epidemic CMC and Epidemic DiseasesDiseases

Causative agent of disease enters bodyBy CMC, replicates itself inside bodyHijacks normal body processes of

oxidation, etc. to support its own replication

Disruption of normal body processes causes symptoms of disease (irreversible in extreme cases)

““Communication”Communication”“Mode of Communication” of epidemic

diseases“Communication” among molecules

accounting for continuity of vital processes– infections agents as packets of information (computer viruses?)

Social and cultural communication as analogous flows of information

The communication of certain molecular changestaking place in the brain is by no means confined to…parents and offspring, but extends collaterallyin all directions, by means of vibrations in the air…If the brain of an animal is in a particular state ofmolecular action, from any object that excites fearor joy, it may cause a similar state in the brain ofothers of the species, by uttering a cry or merelyassuming a particular demeanour.

The faculty of speech gives man a power ofcommunicating his complex feelings and ideas, far exceeding that of lower animals; and theinvention of literature has greatly increased this power in civilized nations. By speech, not onlycan fresh sensations and ideas be communicated,but also that continuation of them calledremembrance, by which they revive after, it may be a long interval of suspended animation.

Snow’s Social VisionSnow’s Social VisionAccording to Snow, his oration “On

Continuous Molecular Changes” was itself an example of continuous molecular change in human organisms and human society

Both chemical and social processes viewed as governed by patterns of information flow (“communication”)