Allen J Frances M.D.

DSM5 in Distress

DSM 5 Minor Neurocognitive Disorder

Let's Wait For Accurate Biological Tests

Posted Feb 16, 2012

Within the next 3-5 years, we will likely have biological tests to accurately diagnose the prodrome of Alzheimer's disease (AD). Much remains to be done in standardizing these tests, determining their appropriate set points and patterns of results, and negotiating the difficult transition from research to general clinical practice. And, given the lack of effective treatment, there are legitimate concerns about the advisability of testing for the individual patient and the enormous societal expense with little tangible benefit. Despite these necessary caveats, there is no doubt that biological testing for prodromal AD will be an important milestone in the clinical application of neuroscience.

How does this impact on the DSM 5 proposal to include a Minor Neurocognitive Disorder as a presumed prodrome to AD? Clearly, the advancing science makes this proposal premature and unnecessary. Any DSM 5 definition has necessarily to be based exclusively on extremely fallible clinical criteria that will have unacceptably high false positive rates—surely exceeding 50 percent. Why scare half the people taking the tests unnecessarily, especially when there is no effective treatment even for those who are true positives?

Accurate diagnosis for prodromal AD most certainly requires biological tests and, fortunately, these are now well within reach. No purpose can possibly be served by rushing ahead with a second rate clinical method of prodrome diagnosis when accurate biological testing will so soon be available. DSM 5 can make a far better choice. It has declared itself to be a 'living document' with plans for continuing, ongoing revision as new findings justify changes. Prodromal AD is the perfect diagnosis for implementing this plan. Hold off for now and then add an Alzheimer's prodrome only after the biological tests have proven themselves able to diagnose it accurately.