Nosology for Dummies

Nosology is a word that most people will never encounter.  The first time I saw it, in a medical text, I thought briefly that it referred to the study of noses.  But I knew better.  Almost all the formal medical terms we use today are derived from Latin or Greek roots, and they don’t say “nose” in either of those languages.

And as everyone knows, otolaryngology is the study of noses.  However, words like that – with no obvious connection to the modern English language - are cumbersome, and meaningless to the average person. That is why otolaryngologists are commonly called ENTs, or ear nose throat doctors.

Nosology is another such word, being derived from ancient Greek, where ‘nosos’ means ‘disease’ and ‘logia’ was the word for ‘study of.’

Today’s nosologists generally work in public health, or healthcare administration.  They oversee the vast systems used to code the millions of medical procedures and treatments that are paid for by government agencies and private insurers each year. The back office gnomes who code procedures for Medicare billing at your local hospital are nosologists, whether they know it or not.

At a higher level, nosologists develop the coding and categorization systems that are used to describe disease and disorder, and keep medical records and statistics.  Diagnostic definitions are increasingly standardized around the world, and coding systems are moving in that direction. This paper gives a short history of that process.

1 - Describing Disease

Humans have been describing diseases and counting their sick and dead for as long as we’ve kept written records. Corpse-takers shuffled the streets of medieval England, pushing body wagons and calling out, "Bring out your dead!" Early descriptions and estimates are rough, but accounts of “half the town sick,” “all the little children dead,” or “thousands killed by the plague” pepper the historical narratives of every society.

Even now, public health catastrophes like plague live on in oral histories. Church officials recorded christenings, marriages, and burials to keep track of the congregation.  Town clerks (or whatever they were called in days past) kept track of who was alive and who was dead so they knew where to look for taxes.  Doctors and healers kept track of how many patients they saw, and what was wrong with them.

The first accounts were very basic.  At the beginnings of life there were the church christening books, which listed the infants (who might not even have a name), the parents, and the date.  At the other end, there were what we now call mortality records – simple lists of those who died. The arrival of plague in the late middle ages made governments take notice of mortality, and what was killing the populace.

London was one of the first cities to keep more sophisticated records, beginning in the late 1500s.  By 1630 that city’s Bills of Mortality were published weekly, and they included causes and places of death in addition to the names. Corpses were examined, relatives were interviewed and parish clerks were employed to summarize the accounts. The terms they used to describe illnesses can cause problems for modern researchers when meanings have changed or been lost.  Terms like “flux” have meant different things at different times, phrases like “touched by the King” are unknown to most present-day medical people.

The modern concepts of demographics and statistics evolved in part from analysis of those records in the late 17th century. It was actually a London haberdasher (a dealer of buttons, ribbons, purses, hats and gloves) who created the first enduring example of that.  His analysis of London’s Bills of Mortality was significant enough for King Charles II to name him a Fellow of the Royal Society.  John Graunt’s 1662 book - Natural and Political Observations Made uponthe Bills of Mortality – now stands as the first known treatise on epidemiology and public health. In this remarkable work, Graunt tabulated births and deaths in the London area, beginning in the early 1600s.  He summarized deaths by cause, age, sex, and location.

Graunt’s listing of the leading causes of death in 1632 London shows just how far we’ve come with public health and medical care:
  • ·      Stillborn or infant death – 2,713
  • ·      Consumption – 1,797
  • ·      Fever – 1,108
  • ·      Old age – 628
  • ·      Small pox - 531
  • ·      Bad teeth - 470
Of those leading causes of death not one remains on the list today.  

Some of the less common causes of death were:
  • ·      Executed and pressed to death – 18
  • ·      Murthered (the old form of murder) – 17
  • ·      Made away with themselves - 15
  • ·      Starved dead in the street – 6
  • ·      Lunatic – 5
  • ·      Killed by a Wolf - 1
It is probably safe to say that anyone killed by a wolf in present day London would still make the news.  In that, the worlds of 1662 and today are the same.

Quaint as some of those descriptions seem, the Mortality Bills and Graunt’s analysis of them were major achievements for the era; particularly at a time when magic and superstition still retained a strong influence over the practice of medicine.

Over the next 150 years several more classifications of disease were published.  Sauvages’ Nosologia Methodica [Method of Classifying Diseases] and Linnaeus’ GeneraMorborum [Varieties of Diseases] both appeared early in the 18th century.  By the turn of the century the most widely used system was the one from William Cullen’s Synopsis Nosologiae Methodicae [Synopsis of Disease Classification.]

The medical foundation that those works were based on has long since been superseded, but the organizational concepts and the names of many disorders have endured.  The next leap forward came in 1893, when French physician Jacques Bertillon introduced his Classification of Causes of Death at a congress of the International Statistical Institute in Chicago.  Bertillon’s Classification was the first enduring work to describe disease in ways that make sense to the present day.  He applied modern scientific principles, with the knowledge of the day. His work - and his method - was adopted by the City of Paris and later by other cities and countries.

Bertillon’s original work was revised and expanded after 1898, when the American Public Health Association recommended widespread international adoption and regular revision, which took place over the next decade. Today, Jacque Bertillon’s name is largely forgotten but his work has lived on. As an interesting aside, his brother Alphonse achieved lasting recognition for his Bertillon system of measurements to identify criminals. He’s the one who put numbers to “the criminal face.” That notion has since been discredited (today’s critics call it profiling,) but lawmen everywhere still remember Bertillon fondly as the father of the mug shot.

The first conference to revise what had become the International Classification of Causes of Death took place in 1900, following its adoption in 26 countries, including the United States.  Subsequent conferences in 1910 and 1920 updated Bertillon’s original work and carried it into the twentieth century.  The Classification was still simple enough to be contained in one book, but that was about to change.

After Bertillon’s death in 1922, responsibility for the Classification moved to an entity called the Mixed Commission, which was made of representatives from the International Statistical Institute and the League of Nations Health Organization.  Under their stewardship the classification system expanded to include “things that make you sick” in addition to “things that killed you.” The technical term for that is “morbidity and mortality.”  It also acquired a new title: International Statistical Classification of Diseases, Injuries and Causes of Death.  That mouthful was abbreviated to ICD, a term that remains in use today.

When the League of Nations assumed responsibility for the ICD it was with the understanding that the committee would develop a standard set of definitions of disease and disorder for the world.  International travel was becoming more common, and it was important to know if flu in Canada was the same as flu in Hong Kong.  At the time, many diseases had local names (unknown elsewhere,) and other disorders were called by several names in different parts of the world.

In 1948, following the formation of the United Nations, the newly created World Health Organization (WHO) continued that mission as they assumed responsibility for the ICD.  They changed the name once again to International Statistical Classification of Diseases.  The sixth revision – ICD-6 – appeared in 1949.

One noteworthy feature of ICD-6 is that it was the first ICD revision to describe disorders of the mind.  The original psychiatric section of ICD-6 was derived in large part from a 1943 U.S. War Department classification scheme called Medical 203, developed by a committee headed by psychiatrist Brigadier General William C. Menninger. Medical 203 was used by the American armed forces through WWII and then refined by the Veteran’s Administration and the individual services.   

Building on that, the WHO released the seventh and eighth revisions in 1957 and 1968, respectively.  ICD-9 came along in 1975, and a derivative  - ICD-9-CM - remains in use in the United States today.  ICD – as defined by the WHO in its various forms – is now accepted as the standard set of definitions of disease and disorder for all WHO member nations.  WHO member nations are UN member countries that accept the WHO constitution or are voted in by the World Health Assembly.  As of this writing, there are 193 member states in the UN and 194 members of the WHO.  Only Kosovo, Taiwan, and Vatican City are not members of either.

Shortly after ICD-9 was published work began on ICD-10, which was expected to be a major enhancement.  ICD-9 contained 17,000 diagnostic codes.  In its final 1994 form, ICD-10 offers more than 155,000 codes – a level of descriptive diagnostic precision almost ten times greater than ICD-9.  It’s truly a compendium that exists to support massive computer databases, and indeed could not be sustained without them.  Earlier versions of the ICD were printed books one could take down and thumb through; ICD-10 and its successors are virtual - computer code and electronic indexing systems. 

ICD codes are structured in a tree format based on etiology.  These are the letters and headings of the top-level classifications that make up the central branches in ICD-10:
  • A and B - Infectious and parasitic diseases 
  • C - Neoplasms  (tumors, both cancerous and benign)
  • D - Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism 
  • E - Endocrine, nutritional and metabolic diseases 
  • F - Mental and behavioral disorders (psychology and psychiatry)
  • G - Diseases of the nervous system 
  • H - Diseases of the eye and adnexa 
  • H - Diseases of the ear and mastoid process  
  • I - Diseases of the circulatory system 
  • J - Diseases of the respiratory system 
  • K - Diseases of the digestive system 
  • L - Diseases of the skin and subcutaneous tissue 
  • M - Diseases of the musculoskeletal system and connective tissue 
  • N - Diseases of the genitals and urinary system 
  • O - Pregnancy, childbirth and the puerperium 
  • P - Certain conditions originating in the perinatal period 
  • Q - Congenital malformations, deformations and chromosomal abnormalities 
  • R - Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified 
  • S/T - Injury, poisoning and certain other consequences of external causes 
  • V - External causes of morbidity and mortality  (accidents, murder, etc)
  • Z - Factors influencing health status and contact with health services 
  • Codes for special purposes 

Within those large categories disease and disorder are broken down ever more finely, as shown in this example:
Group F – Mental and behavioral disorders
F80-F89 – Disorders of psychological development
F84 – Pervasive Developmental Disorders
F84.5 – Asperger’s Syndrome
F84.5.11 – Asperger’s with atypicality in symptomology

As you can see, the ICD provides a high level of definition precision when needed, but for many purposes the higher level diagnoses like F8, F84, or their synonyms will be adequate.  Most people in the United States know F84 by its street name - the autism spectrum. 

Adoption of ICD-10 was relatively rapid in most of the world, except for the United States.  Some countries made slight national modifications but within a few years most WHO Member nations described and reported medical conditions with ICD-10 coding.

The WHO collects the various nations’ reports and consolidates them in what they call the Global Health Observatory Data Repository. Their job is to watch over the word’s health, and use statistics to point medical corps toward problems in need of solution.  This year, for example, they identified two million preventable deaths from indoor smoke from cooking fuels.  They determined that 88% of diarrheal deaths are due to contaminated water and poor hygiene.  Our ability to discover vital statistics like those is founded on the standardized descriptions of ICD.

Given that, why is the United States lagging behind the rest of the world in adopting ICD-10?  It started in 1979, when the U.S. Department of Health and Human Services began requiring ICD-9-CM codes on Medicare and Medicaid claim submissions.  When that happened private health insurers adopted ICD-9-CM as well, and the system quickly became “too big to change.” 

In 1999 the United States government switched to ICD-10 codes for reporting mortality.  At the same time, the U.S. National Center for Health Statistics received permission from the WHO to construct a US-specific edition of ICD-10 as several other countries had done.  The deadline for ICD-10 adoption was originally fall 2013, but it has now been pushed back to fall 2014.

The American Medical Association has vigorously resisted adoption of ICD-10, arguing that it will cost too much, be too time consuming, and proposing that “other systems should be investigated.”  After 20 years of delay the United States is now the only developed country that has not adopted ICD-10.

Meanwhile, the WHO is hard at work on ICD-11, which is due to be presented in draft form in 2015.  Hopefully the United States will have fully adopted ICD-10 before its replacement comes online.  The transition from 10 to 11 should be easier because the basic structure has not changed as much as it did from 9 to 10.

2 - Describing Mental Health

Linnaeus, Sauvages, and Cullen all described disorders of the mind in the 18th century, and many of the conditions they describe were recognized considerably earlier.  Known disorders included stroke and paralysis, hypochondria, epilepsy, madness, melancholia, hysteria, mania, delirium, and “idiotic insanity.”  In their day, those disorders were associated with dysfunction in other parts of the body rather than the mind.  It’s tempting to say they had no idea of the true causes, but the fact is, we are not tremendously more informed about causation of some of them today.

What mechanism, for example, makes one a hypochondriac? 

Definitions are one piece of the puzzle.  Statistics are another.  In America, modern mental health statistics first appeared in the Statistical Manualfor the Use of Institutions for the Insane.  That august publication came from the Committee on Statistics of the American Medico-Psychological Association (the predecessor of the American Psychiatric Association) and the National Commission on Mental Hygiene. The Statistical Manual identified 22 groups of mental illnesses, and was revised 10 times between its 1917 creation and its last issue in 1942.

When World War II ended, and the United Nations was chartered, one of the first topics of discussion was world health.  The result of those 1945 conversations was the creation of the World Health Organization, which opened for business on April 7, 1948.  One of the WHO’s first accomplishments was taking over the responsibility for ICD, and completing the work for the sixth revision, which included for the first time a section on mental health and disorders of the mind.

With the 1949 ICD-6 basing much of its mental health section on Medical 203 – an American military classification system originally developed in 1943 – the leadership of the American Psychiatric Association saw an opportunity. 

The APA committee rolled together a new guide, based on a combination of the original Medical 203, the version of 203 adapted by the Veteran’s Administration, and the language used in ICD-6.  They circulated that to a group of APA members, who offered further suggestions, and voted to proceed with publication.  The final product was published in 1952 as the Diagnostic and Statistical Manual of Mental Disorders, or DSM.  After its first revision the original DSM became known as DSM I.  Successive revisions were identified with Roman numerals until last year, when APA switched to a decimal system that will allow for fractional revisions, more like computer software.  Today’s revision is DSM5, which will be updated as DSM5.1, 5.2, and so on.

The DSM found immediate favor in the United States where there was widespread skepticism of the United Nations and the idea of world government.  American psychiatrists seemed to believe their nation’s professional society represented the field better than the more diverse group of psychiatrists serving on committees of the World Health Organization.  At that time, the APA was a long-established professional society while the World Health Organization was still in its infancy, and many Americans felt a strong sense of primacy after winning World War II.

Other groups in the United States quickly followed this lead.  The DSM became the standard reference used by American psychiatrists, psychologists, and all sorts of institutions.  Colleges and Universities based their psychiatry and psychology programs on its definitions.  Our government may have agreed that ICD would be the standard for the United States, but the APA’s success in marketing DSM ensured that few mental health practitioners in America even heard of ICD. Yet elsewhere in the world the ICD was becoming the established standard in both mental health and regular medicine.

The APA guarded its newly created franchise zealously.  The ICD was a public creation, sponsored by the United Nations through the WHO and shared freely in the interest of improved public health.  The DSM was a private construct, copyrighted and sold to support an American professional society.  Outside the APA community some were troubled by that action, given that DSM was originally developed from publicly funded research and documents.

Like ICD, DSM grew with every revision.  The committees that revised DSM tried to keep it generally consistent with ICD, but some basic structural differences emerged, and those have proven difficult to resolve.  DSM-IV organized diagnoses into five “axes” relating to different aspects of disorder or disability.  These axes have no relationship to the structure of ICD. That philosophy was perpetuated in the current (2013) revision of DSM, DSM5.

To explain the structural difference in simple terms, imagine ICD as a bush with smaller and smaller branches sprouting from a few central trunks.  That is the ICD’s general organizational philosophy, with the major branches representing the skeletal system, nervous system, etc. and smaller and smaller branches defining disorders in those major areas more and more precisely.

DSM seems superficially to have a similar goal but there are only five branches, none of which bears any relation to ICD, and onto which every disorder has been affixed like lines on a ruler.  DSM collects and categorizes mental disorders based on signs and symptoms, rather than underlying causes.  ICD is more cause-based in its approach to mental health, though neither system can be fully cause-based in light of emerging knowledge of the biological foundations of many psychiatric disorders.

That has caused considerable conflict between the current DSM5, and the ICD.  Structural differences between the two guides make resolution of some conflicts impossible. Other challenges to DSM are based on the inherent inaccuracy of its basic approach.  Some have suggested abandoning the DSM; an idea the American Psychiatric Association has resisted, as sales of DSM materials have become one of APA’s largest sources of revenue.

APA has been very successful at marketing their creation.  DSM has become the standard mental health reference in American colleges, American workplaces, and popular culture.  Many clinicians grow up, get an education, and obtain a professional license with absolutely no awareness of ICD.  That provincial philosophy has served APA very well but it sometimes puts Americans at an unwitting disadvantage on the world stage. 

The diagnostic effectiveness of DSM has been challenged many times over the years, and the conditions pathologized within its pages have often mirrored the social mores of the time, not always wisely.  As an example, homosexuality was added in one revision and removed in a later one.  One of the biggest recent controversies was the 2013 redefinition of autism, which highlighted a structural problem with DSM as compared to ICD.  DSM’s linear arrangement meant that the ICD’s F84 autism spectrum was represented as a series of discrete diagnoses in DSM IV.  That created the false impression that they existed independently, when in fact they were related. When those individual diagnoses were eliminated and a new diagnosis – autism spectrum disorder – was created to consolidate them, a huge uproar ensued.

Few people realized that the root problem was not the autism definition, but the fact that the United States public health system was using a privately produced and not fully compatible set of definitions alongside the ICD, which our government had previously agreed to make the primary set of health definitions.

In the spring of 2013, National Institutes of Mental Health Director Tom Insel said his agency would abandon DSM because “patients with mental disorders deserve better.” With that in mind, “NIMH has launched the Research Domain Criteria (RDoC) project to transform diagnosis by incorporating genetics, imaging, cognitive science, and other levels of information to lay the foundation for a new classification system.”

RDoC is a more complex system, but it is based on the foundation elements, rather than top-level symptoms.  As director Insel explained, the present DSM system is like basing treatment for heart disease on the quality of chest pain, or the treatment of infection on the degree of fever. 

That was how treatment was approached in the early days of medicine. However, in the past century symptom based diagnosis and treatment has been replaced by treatment directed at causation as we have learned that symptom treatment rarely leads to the most effective outcomes.

What will that mean for researchers, going forward?  Here’s an example.  Yesterday, a researcher might have proposed a study to investigate a child’s inability to make sense of words at the molecular level.  Clearly, the DSM is poorly adapted to describe work like that, even though it describes the symptom – language and communication disorder.  It’s hard for anyone to relate molecular biology to language problems without an intervening explanation.

Under RDoC, a researcher might instead propose a study of glutamate involvement in cochlear hair cells that influences DSM symptoms at a very basic level.   The glutamate/cochlear description sums up the research very well, and it may ultimately have implications for a dozen DSM disorders.  With mental health research moving to that level in many areas RDoC is a framework that fits.  Trying to place a study like that in the context of DSM has ceased to make sense in the face of evolving medical knowledge.

Another way to look at it is this:  Psychiatry is the study and treatment of medical disorders of the brain.  Modern medicine is moving toward a very elemental level of diagnosis and treatment in many areas.  Psychiatry – due to the complexity of the brain – was perhaps one of the last to move that way too.

Psychology may be distinguished from psychiatry by calling it the study and treatment of mental health symptoms.  Research in psychology may remain symptom-directed when there is no underlying biological foundation.  However, the more we learn about the workings of the brain, the more we find foundation effects that drive symptoms. 

Some psychology will always remain symptom based.  Sadness at the loss of a friend – for example – has no underlying biological cause, though we now realize prolonged sadness can have biological effects.  Many of the feelings that trouble us can be said to occur naturally through the experiences of life, and we will always need help resolving some of them.  But then there are the others, which are based in biology, and there are some people’s unexpected responses to ordinary events, which turn out to be founded in neurological difference.

For example, high precision brain imaging is showing us areas of dysfunction in reading comprehension, and depression.  Brain stimulation targeted at the different areas implicated in those two conditions is proving effective in treatment of both.  Once again, we have found an area of study – brain stimulation to change localized brain plasticity – that is impacting multiple DSM disorders.  Describing that research strictly in the context of depression or dyslexia would impose unfair limitations, and frankly, cause much potential progress to be wasted.  That is why more and more research funders are following the NIMH lead and moving away from the DSM model.

Given recent scientific discoveries, we can be sure basic biology and genetics will play a bigger and bigger role in treating tomorrow’s disorders of the mind.  But the psychologist’s traditional role will expand, too.  Science may show us how to unravel or head off a low-level neurological change that produces disability, but the psychological effects of living in the previous state will remain and those will probably be addressed in ways familiar to psychologists today. Psychologists and neurologists will very likely become partners in treatment for a good many conditions, and achieve far more together than either previously achieved alone.

Today’s psychologists continue to make advances in talk therapies, and given the fact that a significant number of mental health problems are rooted in environment and life experience, rather than biology – continued development of new therapies will remain vitally important.  Our evolving understanding of brain function will enhance tomorrow’s talk therapy, and we need to be sure the descriptive systems we use in research encourage that.

Psychologists may see their job as helping people develop along a healthy trajectory.  However, life choices that are optimal for one person may be less so for another, due to subtle neurological differences that we are just now beginning to understand.  These differences are becoming recognized and respected through movements like neurodiversity.  Development of psychological counseling tools for a neurodiverse world will be a major challenge for psychology researchers in decades to come.

 It’s also worth noting that the “translation horizon” for medical breakthroughs – the time it takes go from laboratory discovery to treating patients in the field – is very long for basic neuroscience.  In psychology there is a different but equally long translation horizon as new talk therapies emerge, get validated, and then wend their way through a long process of gaining third-party-payer acceptance.  That means the therapies psychologists use today will continue to predominate for some time to come and any descriptive system (ICD, ICF, or DSM) must accommodate the present while also facilitating smooth evolution into the future.

The Department of Health and Human Services is committed to fully switching to ICD-10 for fall 2014.  Private insurers and hospital systems should change their systems at the same time.  It is possible that DSM’s place will change in the midst of this transition; it is this writer’s opinion that we would be better off abandoning it entirely for the ICD, though that is unlikely to happen.

3 – Mental Health, Kids, and School

With all the talk of ICD and DSM, it’s easy to miss the elephant in the room, when it comes to mental health services for children – the public school system.  Governments and health insurance providers use ICD and DSM definitions, and the understanding of needs should be the same across the country.  Thanks to standard definitions, a person can go to the doctor in Virginia, take his medical record to California, and pick up right where the Virginia services left off.  The accepted treatments tend to be consistent though insurance coverage may vary.

School districts in many states do not follow this model.  They often employ school psychologists (often certified differently from private practice child psychologists) who evaluate children and render “educational diagnoses” that can be at odds with what a child’s pediatrician may have diagnosed.

Schools provide mental health services to millions of kids through special education programs.  School districts often decide on prepackaged set of services for a narrow range of diagnoses, and then attempt to fit all kids with special needs into one of those molds.  For example, the may have “packages” for autism, PDD-NOS, and dyslexia. That can work well, or it can be a disaster.

Primary and secondary schools do not have an imperative to adopt ICD or any other set of psychiatric/psychological definitions.  All they are charged with is graduating students who meet accepted academic standards.  They are required to give every kid a fair chance, and ensure an equal shot at education. That means they must work to remediate disabilities that affect children’s’ performance in school.  That may mean they guide the child’s psychological development in a positive way, or it may not.

For children with significant emotional problems or developmental challenges the public school system will generally be their principal source of mental health support. Yet the professionals who provide those supports may be unknown to the local medical and mental health establishment.  In other communities, they collaborate and work well together.

Therapies commonly provided in schools include:
·      Speech and language therapy
·      Autism and ADHD therapy
·      Applied Behavior Analysis
·      Social skills therapy
·      Cognitive behavioral therapy
·      Behavior and anger management
·      Therapies for dyslexia and cognitive impairments

A broader discussion of school psychology is beyond the scope of this paper.  That said, anyone who plans to work with children in America (and in many other developed nations) should be aware of this parallel system of mental health services, and how it functions in the area where you expect to work.

4 - Quantifying What Works, and What Doesn’t

With the ICD describing disease, there remained a need for a framework to help researchers and the public health communities understand how various conditions affect us.  It became clear that a standard set of descriptions for function was needed.  Enter the International Classification of Functioning, Disability and Health, or ICF.  The WHO released ICF as a companion to ICD in 2001, and it has been adopted as the standard to describe and measure heath and disability at both the population and individual levels.

In their words, “the ICF puts the notions of ‘health’ and ‘disability’ in a new light. It acknowledges that every human being can experience a decrement in health and thereby experience some degree of disability. Disability is not something that only happens to a minority of humanity. The ICF thus ‘mainstreams’ the experience of disability and recognizes it as a universal human experience. By shifting the focus from cause to impact it places all health conditions on an equal footing allowing them to be compared using a common metric – the ruler of health and disability. Furthermore ICF takes into account the social aspects of disability and does not see disability only as a 'medical' or 'biological' dysfunction. By including Contextual Factors, in which environmental factors are listed, ICF allows us to record the impact of the environment on the person's functioning.”

ICF contains 1,000-some codes, organized into these major areas:
  • ·      B - Body functions
  • ·      S - Body structures
  • ·      D - Activities and participation
  • ·      E - Environmental factors

Within those headings we find a tree arrangement much like ICD.  For example, in section E we can find:
-           E – Environmental
                        E4 – Attitudes
                                    E410 – Individual attitudes of immediate family members.
In section B we see:
-           B – Body functions
                        B1 – Mental function
                                    B126 – Temperament and personality functions
                                                B1264 – Openness to experience

When the codes are used they are qualified by severity index.  The code that signifies difficulty climbing stairs – for instance – could be qualified from “slight impairment” to “total inability to do the task,” thereby painting a vivid picture of the way a person is actually impacted. Environmental factors are qualified by the degree to which they facilitate or inhibit.   In some cases human function is enhanced as well as inhibited.

Within its structure the ICF is capable of describing any human ability, or disability, and how it affects the individual’s relationship to surrounding people and things.  Like RDoC, ICF can be used to describe research or therapy needs more effectively than ICD alone.  

ICF covers both medical and mental functioning.  Using ICF, a clinician can describe and quantify the impact of a broken leg, a stroke, psychosis or depression.  With a fairly small set of codes, a user of ICF can distinguish a teen with Asperger’s from an adult with non-verbal autism.

The total number of ICF codes is large, but any given situation only involves a small subset. Recognizing that, the WHO is encouraging the development of ICF Core Sets, which are sets of ICF codes associated with a particular disorder.  For example, in mental health, there are now distinct ICF Core Sets for bipolar disorder and depression. These compliment the core sets for heart disease, and other general medical conditions. 

Core Sets make ICF much easier to use by distilling many pages of codes into a few succinct lists that are relevant to the disorder being studied or treated.  A physical therapist might look at the Core Set for heart disease and see the physical rehabilitation issues.  A surgeon might look at the core set and see the blood flow problems that are corrected with a stent.  A researcher might look at the core set as describing the ultimate manifestation of a low-level biological process.

The creation of Core Sets allows researchers to identify aspects of function or disability that are common to multiple disorders.  When combined with the RDoC initiative the trio of standards represents a powerful set of tools to define and shape future research efforts.

Core Sets help service providers understand the range of treatments or therapies that will be useful in a given situation.  Conversely, the relationship of services to ICF codes to disorders may show us new applications for existing treatments and therapies. 

4 - Putting it All Together

The World Health Organization has a number of groups who are developing and optimizing the core ICD and ICF tools for research and treatment in many different environments.  National groups are constantly at work adopting these standards for the insurance and administrative structures of their countries.

ICD and ICF have their flaws, but they share one great benefit:  They are open-source collaborative projects.  If you feel there’s a problem with any portion of the ICD or ICF versions under development, you can register as a contributor and present your arguments for peer review and consideration.  Every interested party who perceives a problem can thereby become part of the solution.

There is incalculable value to having accepted world standard definitions for disease, disorder, difference, and function.  ICD is what makes public health statistics possible, and it and ICF have been adopted throughout the world for this purpose. I strongly believe that should be reinforced and continued.

Outside the United States, there are a few other countries where national professional societies have tried to go their own way as APA has done with the DSM.  For the most part, those efforts have been subsumed into the larger WHO projects. 

In general, I feel the development of separate national standards is a bad idea, because it fosters isolation and confusion.  Arguments are made for the superiority of one system over another, but I feel they should be resolved by evolution of the accepted standard, not by perpetuation of a competing standard for one country.  In that light, the expansion of DSM into Canada and the UK is probably a bad idea.

WHO committees are made up of representatives from all regions of the world.  The United States is a leader in medical technology and education, but the majority of the world’s population lives in the Indian subcontinent and Asia. Consequently, a majority of the world’s public health concerns lie outside our borders.  America is influential at WHO, but not dominant.  There is no WHO equivalent to the UN Security council, where a few nations can halt everything with a single vote.

I have found exposure to WHO committees eye opening, as it has shown me the true scope of medical and mental health issues, and the true diversity of understanding and opinion that surround them.  I see how insular it’s possible to become in one country or within that, in one agency.

In years to come I hope to see WHO pick up the American RDoC effort, refine it, and integrate that into their ICD/ICF framework, so that it too can be standardized and shared with the larger community.

Today’s students of psychology and psychiatry would be wise to familiarize themselves with RDoC, ICD, and ICF, even if most of their teaching is based on DSM.  The medical community is increasingly international, particularly for those involved in research. ICD and ICF are the “international languages” of medical and mental health. RDoC probably represents the basis for describing the research of tomorrow.

In closing, it’s worth noting that any manual that purports to describe disorders will of necessity define those disorders in the context of the society within which the manual is written.  Consider the context when reading historical descriptions, and try to envision the future when you write today.

The earliest descriptions of physical sickness and disorder characterized symptoms in ways we still recognize.  Plague was a deadly disease in 1700 and it remains a deadly disease now.  Injuries are seen much the same too, though we have many more options for treatment.

Our understanding of what constitutes a disorder of the mind has changed tremendously since the first manuals were written.  In the seventeenth century, only the most visible and severe psychiatric conditions were even recognized.  Many more subtle disorders – like dyslexia or mild autism – were either invisible or irrelevant in the cultural context of the time. Today we recognize hundreds of psychiatric disorders and our definitions of them change every year.  Looking forward, it’s possible to foresee the characterization of wholly new disorders that are based on inability to interact with machines and artificial intelligences; technological creations that do not exist today but can be vaguely imagined.

As society, science, and technology change and evolve, so our definition of disease and disorder will change and evolve.  It’s a process that never ends, and gets more complex with every passing day.

John Elder Robison
The College of William and Mary
January 2014


I have no financial stake in any of the ideas presented in this paper.  However, I do have some association with the organizations mentioned.

Over the past six years I have served on various US Government committees where many of the issues above were discussed.  I am a member of the Interagency Autism Coordinating Committee of the US Department of Health and Human Services, and I’ve been part of ethics and research policy committees for both the National Institutes of Health and the Centers for Disease Control. 

I am currently a member of the steering committee for the ICF Autism Core Set initiative, a WHO-affiliated effort based at Karolinska Institute in Stockholm. I’m an advisory board member for CSESA, the US Dept. of Education funded initiative to improve post high school outcomes for students with autism

I am a contributor to ICD-11 in the area of autism and pervasive developmental disorders, and I offered comment and discussion with the APA DSM5 autism work group.

For further study:

Professor Emeritus Ed Stephan’s online guide to Graunt is here:

Uppsala University (Sweden) Linnaeus website:

Read NIMH Director Tom Insel’s April 2013 essay on transforming diagnosis with RDoC here:

Read more about the predecessors to the ICD, and the development of the ICD in Volume 2, Chapter 6 of the ICD-10 reference:

Here is the American Psychiatric Association’s official history of the DSM:

Explore the 2010 revision of ICD-10 (note that an Internet search will reveal many third party descriptions and several national variants of ICD.  This link goes to the WHO’s “master copy,” as it were:

Learn about ICD-11 (due for release in 2015) and participate in its revision:


Unknown said…
hello mr. elder are you the one on the cover of your book
Unknown said…
Mr. Robison probably doesn't care to be called Mr. Elder ;-) Lol
Usman Qazi said…
An Oto-*Rhino*-Laryngologist is an E*N*T specialist.

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