Latent Structure Models & Statistical Foundation for TCM Nevin L. Zhang The Hong Kong University of Science & Techology

Page 2 Latent Variables in TCM Theories Symptoms intolerance to cold, cold limbs, and cold lumbus and back, loose stools, indigested grain in the stool. Syndromes kidney yang deficiency, kidney yin deficiency, kidney essence insuficiency observed variables latent variables manifest variables

Page 3 Where Do Latent Variables Come from? Latent variables introduced by human brain to explain regularities that we observe Example: lighting from nearby buildings Regularity observed:  Lighting from several apartments were changing in synchrony My first conclusion: must be a common cause  I did not see it. So, latent variable introduced. What was the common latent cause?  The same TV channel. Interpretation of latent variable.

Page 4 Conjecture of TCM Theory Latent syndrome variables introduced to explain co- occurrence of symptoms. Example: Observed regularity  ‘intolerance to cold’, ‘cold limbs’, ‘cold lumbus and back’ often occur together Latent variable introduced to explain the regularity  Kidney yang failing to warm the body

Page 5 Premise and Idea of the Latent Structure Approach Premise ExperiencesHuman BrainTCM Theory Idea: Reconstruct aspects TCM Theory via modern data analysis DataComputer & Statistical Principles Model Match?

Analysis of Kidney Data Y0-Y34: manifest variables from data X0-X13: latent variables introduced by data analysis

Page 7 Match between Model and TCM Theory TCM Kidney yang deficiency, failing to warm body  intolerance to cold, cold limbs, cold lumbus and back,  Spleen disorders  loose stools, indigested grain in the stool Model Good Match

Page 8 Match between Model and TCM Theory TCM When kidney fails to control the urinary bladder,  frequent urination, urine leakage after urination, frequent nocturnal urination,  (in severe cases) urinary incontinence and nocturnal enuresis. Model Good Match

Page 9 Match between Model and TCM Theory TCM kidney essence insufficiency  premature baldness, tinnitus, deafness, poor memory, trance, declination of intelligence, fatigue, weakness, and so on. Model Good Match

Page 10 Match between Model and TCM Theory TCM kidney yin deficiency  dry throat, tidal fever or hectic fever, fidgeting, hot sensation in the five centers,insomnia, yellow urine, rapid and thready pulse, and so on. Model Good Match

Page 11 Significance of Work Statistical Validation for TCM Theory Supports objectivity of the syndrome factors kidney yang deficiency, … Shows that statistical truths in TCM theory. Data X1 X4 X8 X10 Kidney yang deficiency Kidney failing to control urinary bladder Kidney essence insufficiency Kidney yin deficiency Statistical Principle Match

Page 12 Significance of Work Model-Based Diagnosis TCM Theory incomplete, qualitative, vagueness Diagnois based on TCM theory: Subjective, variability across doctors ExperiencesHuman BrainTCM Theory Model Complete, quantitative, clear Model-based diagnosis Objective, no variability across doctors DataComputerModel