The furor surrounding the recently proposed Alzheimer's Guidelines was provoked by their premature attempt to introduce early diagnosis, well before accurate tools are available. The same laudable, but currently clearly unrealistic ambition has propelled two of the worst suggestions for new diagnoses in DSM 5 - - Psychosis Risk, Mild Neurocognitive.
The concept of early identification and intervention is understandably appealing. The problems that eventually blossom into full-fledged psychiatric disorders do not arise suddenly and de novo. Undoubtedly, they have had a long history of gradual stages with changes that at first cause no symptoms whatever, followed by mild premonitory symptoms, followed by the full blown disorder. Clearly, it would be wonderful to prevent the progression and its consequent mounting damage by intervention at the earliest possible moment. Accurate early diagnosis followed by effective early treatment would reduce the direct burden of illness and also its secondary negative consequences.
Optimists among the proponents of preventive psychiatry point to the trend throughout medicine to catch disease earlier and intervene more aggressively. Without going into the merits and risks of early screening in medicine (which remains a mixed and highly controversial issue), the analogy simply doesn't fly. Early diagnosis in psychiatry currently lacks any tools to be helpful and may instead, in its well intentioned and unwitting way, be extremely harmful both to the individual patient and to public policy.
Preventive psychiatry would have to rest on six foundations:
1. A method of diagnosis that is accurate even in the early stages of the disorder
2. A treatment that is effective in improving early symptoms and in preventing their progression
3. A treatment that is safe even if provided over the necessary course of what may be many decades
4. A manageable degree of stigma, worry, and disadvantage from gaining a label that implies risk and progressive impairment
5. A favorable risk/benefit analysis regarding clinical utility
6. A reasonable public policy cost/benefit analysis. Let's see how the psychosis risk and mild cognitive disorders stack up on these necessary benchmarks.
On diagnostic accuracy: neither proposed disorder has a diagnostic measure that is accurate. Psychosis risk has a false positive rate of 70%-90%. Laboratory studies for mild cognitive are still in very early stages of testing.
On treatment efficacy: none proven for either disorder.
On treatment safety: antipsychotic medications likely to be used for psychosis risk frequently produce enormous weight gain and its dire complications.
On stigma and worry: considerable for both. The power to label could here be the power to destroy.
On clinical utility: none for either. It is all risk and no current gain.
On public policy cost/benefit: especially unfavorable for minor cognitive disorder given the very expensive imaging studies and the lack of any clinical benefit.
Before their suggestions will make any sense, the experts in schizophrenia and dementia who are pushing for earlier diagnosis need first to do the research to fill in all the above blanks. Most likely this research enterprise will take a decade (and possibly much more). Until then, caution is safer than wishful thinking.