With three years still left until pub­li­ca­tion, the fights over the new ver­sion of the psy­chi­atric diag­nos­tic man­ual, the DSM-V, are hot­ting up and The New York Times has a con­cise arti­cle that cov­ers most of the main point of contention.

- “What you have in the end,  Mr. Shorter said, “is this process of sort­ing the deck of symp­toms into syn­dromes, and the out­come all depends on how the cards fall.

- Psy­chi­a­trists involved in prepar­ing the new man­ual con­tend that it is too early to say for sure which cards will be added and which dropped.

Although I doubt the DSM com­mit­tee are using that exact metaphor, it cer­tainly illus­trates the point that the process requires a cer­tain degree of value-judgement.

It’s inter­est­ing, how­ever, that the pub­lic debate is cur­rently focused on whether cer­tain diag­noses should be included or not, rather than whether diag­no­sis itself is use­ful for psychiatry.

We’ve had psy­cho­met­rics for a good 100 years that allow us to mea­sure dimen­sions of human expe­ri­ence and per­for­mance with a much greater degree of accu­racy than clin­i­cal diag­no­sis allows.

The slightly obses­sive need to clas­sify every­thing is both an inher­i­tance from the infec­tion model of dis­ease, where one either has the pathogen or does not, and is encour­aged by the US health care sys­tem, where insur­ance com­pa­nies will only pay for treat­ment if it is diag­nosed with an ‘offi­cial’ diagnosis.

Nev­er­the­less, it is per­fectly pos­si­ble to treat some­one based on con­tin­u­ous mea­sures of dis­tress, impair­ment and func­tion­ing using evidence-based cut-off points to judge whether a par­tic­u­lar treat­ment should be applied.

In fact, many phys­i­cal dis­eases are treated in exactly this way. The def­i­n­i­tions of obe­sity, hyper­ten­sion, dia­betes and many oth­ers rely on an evidence-based cut-off point on a con­tin­u­ous scale of weight, blood pres­sure and blood glu­cose level.

There is no qual­i­ta­tively dif­fer­ent cut-and-dry dis­tinc­tion between just below the cut-off and just above it — it’s just the point at which out­come stud­ies pre­dict that other things get much worse.

So rather than ques­tion­ing the process, we need also to ques­tion the sys­tem, because diag­noses are tools and we need to know when and where they are most useful.

Link to NYT ‘Psy­chi­a­trists Revise the Book of Human Troubles’.

– Dr. Vaughan Bell, main blog­ger at Mind Hacks, is a clin­i­cal and research psy­chol­o­gist inter­ested in under­stand­ing brain injury, men­tal dis­tress and psy­cho­log­i­cal impair­ment. He is cur­rently at the Depart­mento de Psiquia­tria in the Uni­ver­si­dad de Antio­quia and the Hos­pi­tal Uni­ver­si­tario San Vicente de Paul, in Medellin, Colom­bia, where he’s a vis­it­ing pro­fes­sor. He’s also a vis­it­ing research fel­low at the Depart­ment of Clin­i­cal Neu­ro­science at the Insti­tute of Psy­chi­a­try, King’s Col­lege London.

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