Dr Godfrey Pearlson Explains the Biological Fingerprints Underpinning Psychiatric Disorders

Classifying mental disorders using traditional tools like the Diagnostic and Statistical Manual (DSM) misses the vast differences in biomarkers that can exist in patients with the same diagnosis, which is why research is looking to biological measures and “biotypes” to provide more information, according to Godfrey Pearlson, MD, professor of psychiatry and neuroscience, Yale School of Medicine.

Transcript

How could biologic measures be used to create a new framework of psychiatric diseases?

So, if you just temporarily toss out conventional DSM-type traditional psychiatric measures and start from the bottom up, using only biology as a classifier, you end up with very, very different syndromes. For example in the B-SNIP project, looking at bipolar illness, schizoaffective disorder, and schizophrenia, when we took that approach to just removing DSM labels from patients with psychotic illnesses, putting them all into one huge group, trying to classify them from the bottom up using biology, we came up with 3 new typologies that we call biotypes.

Each biotype contains people with each of the 3 diagnoses, and they all look very similar symptomatically—they all have hallucinations and delusions and some mood symptoms—but from the point of view of biology they look completely different from each other, even in opposite directions. So some biological measure may be greatly increased above normal in one group, in one biotype, and way below normal in the other, but they, say, may be both containing people with schizophrenia, so you can imagine what would happen if you averaged across people who are way high and way low, you’d just be very confused, which is I think the way biology is at the moment.

So I think if you classify based on biology, which is sort of what RDoC [Research Domain Criteria] from NIMH is trying to do, you end up ahead on average, and more informed, with more facts than you had before.

Which biological measures hold the most promise as indicators for classifying these illnesses and why?

Yeah, well that’s the key question. We really don’t know the answer to that yet. We have a lot of measures, and most likely, I think, in the beginning, we’ll find fingerprints that identify new diseases, classified by biology, that are based on an agglomeration, a mixture of different kinds of biological indicators. I don’t think there’s any one that’s going to be key in the beginning, but it’ll be a mixture that leads to a fingerprint.